SIST ISO 7507-2:2006
(Main)Petroleum and liquid petroleum products -- Calibration of vertical cylindrical tanks -- Part 2: Optical-reference-line method
Petroleum and liquid petroleum products -- Calibration of vertical cylindrical tanks -- Part 2: Optical-reference-line method
This part of ISO 7507 specifies a method for the calibration of tanks above eight metres in diameter with cylindrical courses that are substantially vertical. It provides a method for determining the volumetric quantity contained within a tank at gauged liquid levels. The method specified in this part of ISO 7507 is suitable for tilted tanks with up to 3 % deviation from the vertical provided that a correction is applied for the measurement tilt, as described in ISO 7507-1. This method is an alternative to other methods such as strapping (ISO 7507-1) and the optical-triangulation method (ISO 7507-3).
Pétrole et produits pétroliers liquides -- Jaugeage des réservoirs cylindriques verticaux -- Partie 2: Méthode par ligne de référence optique
L'ISO 7507-2:2005 spécifie une méthode permettant le jaugeage des réservoirs cylindriques pratiquement verticaux d'un diamètre supérieur à huit mètres. Elle décrit une méthode permettant la détermination des volumes contenus dans un réservoir en fonction des hauteurs de liquide mesurées.
Les mesurages optiques (décalages) requis pour déterminer les circonférences peuvent être effectués aussi bien à l'intérieur qu'à l'extérieur des réservoirs.
La méthode spécifiée dans l'ISO 7507-2:2005 convient également aux réservoirs dont l'inclinaison par rapport à la verticale n'est pas supérieure à 3 %, à condition qu'une correction soit apportée pour tenir compte de l'inclinaison mesurée, comme décrit dans l'ISO 7507-1.
Elle est une alternative aux autres méthodes, telles que la méthode par ceinturage (ISO 7507-1) ou par triangulation optique (ISO 7507-3).
Nafta in tekoči naftni proizvodi – Umerjanje navpičnih valjastih rezervoarjev – 2. del: Optično referenčna linearna metoda
General Information
Relations
Buy Standard
Standards Content (Sample)
SLOVENSKI STANDARD
SIST ISO 7507-2:2006
01-februar-2006
1DIWDLQWHNRþLQDIWQLSURL]YRGL±8PHUMDQMHQDYSLþQLKYDOMDVWLKUH]HUYRDUMHY±
GHO 2SWLþQRUHIHUHQþQDOLQHDUQDPHWRGD
Petroleum and liquid petroleum products -- Calibration of vertical cylindrical tanks -- Part
2: Optical-reference-line method
Pétrole et produits pétroliers liquides -- Jaugeage des réservoirs cylindriques verticaux --
Partie 2: Méthode par ligne de référence optique
Ta slovenski standard je istoveten z: ISO 7507-2:2005
ICS:
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
SIST ISO 7507-2:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 7507-2:2006
---------------------- Page: 2 ----------------------
SIST ISO 7507-2:2006
INTERNATIONAL ISO
STANDARD 7507-2
Second edition
2005-06-01
Petroleum and liquid petroleum
products — Calibration of vertical
cylindrical tanks —
Part 2:
Optical-reference-line method
Pétrole et produits pétroliers liquides — Jaugeage des réservoirs
cylindriques verticaux —
Partie 2: Méthode par ligne de référence optique
Reference number
ISO 7507-2:2005(E)
©
ISO 2005
---------------------- Page: 3 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2005
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2005 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Precautions .2
5 Equipment .2
6 Procedure .3
6.1 Principle.3
6.2 Preparation of the tank.3
6.3 Reference circumference.3
6.4 Offset readings.4
6.5 Tank bottom calibration .8
6.6 Other measurements and data.8
7 Tolerances .9
8 Tank capacity calculation procedure .9
8.1 Outside circumference.9
8.2 Corrections.10
8.3 Tank capacity table.10
Annex A (informative) Tank calibration uncertainties.11
Bibliography .26
© ISO 2005 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7507-2 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants,
Subcommittee SC 3, Static petroleum measurement.
This second edition cancels and replaces the first edition (ISO 7507-2:1993), which has been technically
revised.
ISO 7507 consists of the following parts, under the general title Petroleum and liquid petroleum products —
Calibration of vertical cylindrical tanks:
Part 1: Strapping method
Part 2: Optical-reference-line method
Part 3: Optical-triangulation method
Part 4: Internal electro-optical distance-ranging method
Part 5: External electro-optical distance-ranging method
iv © ISO 2005 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
Introduction
This part of ISO 7507 forms part of a series on tank calibration, including the following:
ISO 4269:2001, Petroleum and liquid petroleum products — Tank calibration by liquid measurement —
Incremental method using volumetric meters
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 1: Strapping method
ISO 7507-3:1993, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 3: Optical-triangulation method
ISO 7507-4:1995, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 4: Internal electro-optical distance-ranging method
ISO 7507-5:2000, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 5: External electro-optical distance-ranging method
ISO 8311:1989, Refrigerated light hydrocarbon fluids — Calibration of membrane tanks and independent
prismatic tanks in ships — Physical measurement
ISO 9091-1:1991, Refrigerated light hydrocarbon fluids — Calibration of spherical tanks in ships — Part 1:
Stereo-photogrammetry
ISO 9091-2:1992, Refrigerated light hydrocarbon fluids — Calibration of spherical tanks in ships — Part 2:
Triangulation measurement
ISO 12917-1:2002, Petroleum and liquid petroleum products — Calibration of horizontal cylindrical tanks —
Part 1: Manual methods
ISO 12917-2: 2002, Petroleum and liquid petroleum products — Calibration of horizontal cylindrical tanks —
Part 2: Internal electro-optical distance-ranging method
This part of ISO 7507 describes a method for the calibration of vertical cylindrical tanks by measurement of
one reference circumference by strapping and then determining the remaining circumferences at different
levels from measurements of radial offsets from vertical optical-reference-lines. These circumferences are
corrected to give the true internal circumferences.
© ISO 2005 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 7507-2:2006
---------------------- Page: 8 ----------------------
SIST ISO 7507-2:2006
INTERNATIONAL STANDARD ISO 7507-2:2005(E)
Petroleum and liquid petroleum products — Calibration of
vertical cylindrical tanks —
Part 2:
Optical-reference-line method
1 Scope
This part of ISO 7507 specifies a method for the calibration of tanks above eight metres in diameter with
cylindrical courses that are substantially vertical. It provides a method for determining the volumetric quantity
contained within a tank at gauged liquid levels.
NOTE The optical (offset) measurements required to determine the circumferences can be taken internally or
externally.
The method specified in this part of ISO 7507 is suitable for tilted tanks with up to 3 % deviation from the
vertical provided that a correction is applied for the measurement tilt, as described in ISO 7507-1.
This method is an alternative to other methods such as strapping (ISO 7507-1) and the optical-triangulation
method (ISO 7507-3).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 4269:2001, Petroleum and liquid petroleum products — Tank calibration by liquid measurement —
Incremental method using volumetric meters
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 1: Strapping method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7507-1 and the following apply.
3.1
optical-reference-line
vertical optical ray (virtual) that is established using the optical device at a given location
3.2
magnetic trolley
mechanical device that can be traversed up or down the tank shell wall to measure deviations in the tank shell
relative to the optical-reference-line using a horizontal scale that is mounted on the trolley
© ISO 2005 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
3.3
station
location where the optical device and the magnetic trolley are placed for optical measurements
3.4
horizontal station
station where the optical device is located as it is moved around the tank circumference
3.5
vertical station
station where the magnetic trolley is located along the tank shell wall
3.6
reference circumference
circumference measured at the bottom course that forms the basis for subsequent computations
3.7
reference offset
distance of the shell wall (at each horizontal station) from the optical-reference-line measured at the bottom
course where the reference circumference is measured
4 Precautions
The general precautions and safety precautions specified in ISO 7507-1 shall apply to this part of ISO 7507.
5 Equipment
5.1 Equipment for tank strapping, as follows, as specified in ISO 7507-1:
strapping tapes;
spring balance;
step-over;
littlejohn grip;
dip-tape and dip-weight.
5.2 Optical-reference-line device, such as a precision optical plummet, a precision engineer’s level with a
pentaprism attachment, or a precision engineer’s theodolite with a pentaprism attachment.
NOTE 1 These are optical instruments with a means of attachment to either a tripod, magnetic bracket or other stable
means of support.
The instrument, when set on its support and levelled, either manually using bubble vials or automatically if an
automatic levelling device is fitted, shall be capable of giving a vertical line of sight.
The instrument should preferably be of short focal length so that, when set up at a practical working height, it
can be focused on the scale at the reference strapping level.
The instrument shall have a resolution of at least 1:20 000 and be equipped with a telescope with a
magnification of not less than 20. The pentaprism attachment for use with an engineer’s level or engineer’s
theodolite shall not introduce any significant collimation errors.
2 © ISO 2005 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
NOTE 2 Optical plummets can be fitted with a single optical train, i.e. a zenith plummet, a double optical train or a
single superimposed optical train giving both upward and downward lines of sight, i.e. a nadir/zenith plummet. It is
preferable that the plummet does not have any movable elements in its optical train, such as mirrors or pentaprisms, to
ensure stability of the line of sight.
5.3 Magnetic trolley, of robust construction. Its design shall include the following features.
a) The magnet(s) shall be of sufficient power to ensure that the trolley does not lose contact with the tank
shell in conditions of high wind or when ring joints have to be negotiated or when there are heavy layers
of paint or scale.
b) The magnet(s) shall be adjustable for height so that the clearance between the magnet faces and the
tank may be varied to suit the tank construction and condition.
c) A cord or wire cable shall be attached to enable it to be raised or lowered from the tank roof or, via a
pulley system, from ground level.
d) A graduated scale shall be attached securely to the trolley at its centreline. When the trolley is in its
operational mode, the scale shall be either perpendicular to the tank shell or horizontal.
e) The scale shall be attached to the trolley as closely as possible to the centreline of an axis in order to
reduce errors caused by deformations in the tank.
NOTE Trolleys that are not magnetic can be used to maintain contact with the tank shell.
5.4 Graduated scale, made of steel and marked in millimetre increments. The length of the scale shall be
as short as is practicable and shall be determined by the distance at which the optical equipment can be set
up from the tank side. The scale shall be calibrated using standard methods and standard reference devices.
6 Procedure
6.1 Principle
This calibration method is based on the accurate measurement of a reference circumference using a
calibrated measuring tape at one level on an accessible, non-obstructed course. Repeat measurements
agreeing within specified tolerances are made to avoid any systematic error in the derived circumferences.
The derived circumferences are calculated from the reference circumference, and measurements of offsets
taken at the specified levels and at the reference circumference. These offsets are a measure of the deviation
of the tank wall. They are measured at a specified number of vertical, optical-reference-lines spaced equally
around the tank.
NOTE For examples see Figures 1 to 3.
6.2 Preparation of the tank
For new tanks or for tanks after repair, fill the tank to its normal working capacity at least once and allow it to
stand for at least 24 h prior to calibration.
If the tank is calibrated with liquid in it, record the depth, temperature and density of the liquid at the time of
calibration. Do not make transfers of liquid during the calibration.
For floating-roof tanks where offset measurements may be taken internally, the roof shall be in its lowest
position, resting on the legs.
6.3 Reference circumference
Reference circumference has a direct impact on the calibrated volume of entire tank. It, therefore, shall be
measured as accurately as possible.
© ISO 2005 – All rights reserved 3
---------------------- Page: 11 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
Determine the reference circumference using the reference method described in ISO 7507-1 and the following.
a) Take multiple measurements of the reference circumference either prior to the commencement or after
the completion of the optical readings. If the first three consecutive measurements agree within the
tolerances specified in Clause 7, take their mean average as the reference circumference and their
standard deviation as the standard uncertainty. If they do not agree within the tolerances specified in
Clause 7, repeat the measurements until two standard deviations of the mean of all measurements is less
than the half of the tolerances specified in Clause 7. Use the mean as the measured reference
circumference and the standard deviation as the standard uncertainty. Use standard procedures to
eliminate obvious outliers.
b) Take the measurement of the reference circumference at a position where work conditions allow reliable
measurements, and which is within the focal range of the optical instrument. Strap the tank, aiming at one
of the following levels:
1) 1/4 of the course height above the lower horizontal seam,
2) 1/4 of the course height below the upper horizontal seam;
and repeat the measurement to achieve measurements agreeing within the tolerances specified in
Clause 7.
6.4 Offset readings
6.4.1 Set up the optical-reference-line device (5.2), magnetic trolley (5.3) and graduated scale (5.4)
successively at the horizontal stations (see 6.4.2) that are equally spaced around the tank, as close as
possible to the tank wall. Reference lines shall be chosen such that the trolley does not run over a vertical
seam or its weld.
6.4.2 The minimum number of horizontal stations shall be as given in Table 1.
Table 1 — Minimum number of horizontal stations
Circumference Minimum number of horizontal stations
m
u 50 10
> 50, u 100 12
> 100, u 150 16
> 150, u 200 20
> 200, u 250 24
> 250, u 300 30
> 300 36
NOTE 1 The number of horizontal stations divided by the number of plates in tank segments
should not be equal to an integer (e.g. 1, 2, 3, etc.) in order to avoid systematic errors.
NOTE 2 Using the minimum number of horizontal stations, especially for smaller tanks, can
lead to larger-than-acceptable uncertainties.
4 © ISO 2005 – All rights reserved
---------------------- Page: 12 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
Dimensions in millimetres
Key
1 to 7 horizontal levels 11 graduated scale
8 optical-reference-line 12 weld seam (horizontal)
9 weld seam (vertical) 13 reference circumference taken close to location 1
10 magnetic trolley 14 optical equipment
a) Tank elevation
b) Plan of horizontal stations
NOTE The horizontal stations are designated A to K in the plan view (see also 6.4.2). Of these, only E and F are
shown in the elevation.
Figure 1 — Optical measurement of offsets from tank wall (typical case)
© ISO 2005 – All rights reserved 5
---------------------- Page: 13 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
a) Centreline flush b) Outside flush c) Inside flush
Key
1 optical-reference-line
2 tank centreline
External reference circumference = C
em
External reference radius (bottom course) = C /2π = R
em
Outer radius of second course = R′ , R′ ,
1 2
Course thicknesses = t , t , etc.
1 2
Reference offset = a
Reference radius = R
Individual course offsets = m , m , etc.
1 2
Internal reference radius = R – t = C /2π – t = R
1 em 1 1
Internal radius, second course, bottom = R′
1i
Internal radius, second course, top = R′
2i
Figure 2 — Determination of internal radius from offsets to external optical-reference-line
6 © ISO 2005 – All rights reserved
---------------------- Page: 14 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
a) Centreline flush b) Outside flush c) Inside flush
Key
1 optical-reference-line
2 tank centreline
External reference circumference = C
em
External reference radius (bottom course) = C /2π = R
em
Outer radius of second course = R′ , R′ ,
1 2
Course thicknesses = t , t , etc.
1 2
Reference offset = a
Reference radius = R
Individual course offsets = m , m , etc.
1 2
Internal reference radius = R – t = C /2π – t = R
1 em 1 1
Internal radius, second course, bottom = R′
1i
Internal radius, second course, top = R′
2i
Figure 3 — Determination of internal radius from offsets to internal optical-reference-line
6.4.3 Verify the verticality of the optical-reference-line prior to the commencement of readings by turning the
optical instrument at the first horizontal station through 180°, whereby the difference between the two readings
of the diametrically opposite positions shall be within 1 in 20 000. Also, verify the verticality of the optical-
reference-line at each station at the completion of the readings. If verticality has not been maintained, repeat
the calibration procedure at this station.
6.4.4 Take a minimum of two measurements of offsets from vertical per course at each horizontal station,
aiming at 1/4 of course height above the lower horizontal seam and at 1/4 of course height below the upper
horizontal seam. Read the graduated scale to the nearest millimetre.
6.4.5 At all horizontal stations, measure the reference offset and then take offset measurements
progressively at vertical stations on each course as the trolley is raised up the tank wall. After the last offset
measurement has been taken on the top course, lower the trolley to the bottom course and repeat the
reference offset. The initial and final reference offset readings shall agree to within two millimetres. In further
calculations, use the mean average of the initial and the final offset readings.
If agreement is not obtained, repeat vertical offset measurements at this horizontal station.
© ISO 2005 – All rights reserved 7
---------------------- Page: 15 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
6.5 Tank bottom calibration
Calibrate the tank bottom, preferably by filling with measured quantities of a non-volatile liquid (preferably
clean water), as illustrated in ISO 4269, to a minimum level that covers the bottom completely, immersing the
dip-plate and eliminating the effect of bottom deformations. Transfer further measured quantities of liquid into
the tank until the highest point of the tank bottom is covered and the liquid level is higher than the lowest point
on the tank that will be calibrated by strapping (for example the offset measurement location or the reference
circumference location as appropriate). Alternatively, calibrate the tank bottom by a physical survey using a
reference plane to determine the shape of the bottom as specified in ISO 7507-1.
6.6 Other measurements and data
6.6.1 Determine, using calibrated equipment, and process the following data as described in ISO 7507-1:
a) plate and paint thickness;
b) height of the courses;
c) density and working temperature of the liquid to be stored in the tank;
d) ambient temperature and the temperature of the liquid at the time of measurement;
e) maximum filling height;
f) deadwood;
g) number, width and thickness of any vertical welds or overlaps;
h) tilt of the tank as shown by the plumb line deviations;
i) shape, landing height and apparent mass in air of any floating roof or cover.
NOTE Average mean value and a range of tank shell temperatures are required for uncertainty analysis (see
Annex A).
6.6.2 It is necessary to refer each tank dip to the dip-point, which may be in a different position from the
datum-point used for the purpose of tank calibration (e.g. a point on the bottom angle). Determine any
difference in level between the datum-point and dip-point, either by normal surveying methods or by other
means, and record it.
6.6.3 Measure the overall height of the reference point on each dip-hatch (upper reference point) above the
dip-point using the dip-tape and dip-weight as specified in ISO 7507-1. Record this overall height, to the
nearest millimetre and permanently mark it on the tank adjacent to that dip-hatch.
6.6.4 If possible, compare measurements with corresponding dimensions shown in the drawings and verify
any measurement that shows a significant discrepancy.
8 © ISO 2005 – All rights reserved
---------------------- Page: 16 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
7 Tolerances
Reference circumference measurements shall agree within the absolute tolerances given in Table 2.
Table 2 — Absolute tolerances on circumferential measurements
Circumferential measurement Absolute tolerance
m mm
u 25 2
> 25, u 50 3
> 50, u 100 5
> 100, u 200 6
> 200 8
8 Tank capacity table calculation procedure
8.1 Outside circumference
Calculate the outside circumference from offset readings and the reference circumference by using
Equations (1) to (3):
C
em
R = (1)
2π
R+=aR′+m (2)
R′=+Ra−m (3)
( )
where
C is the reference circumference, expressed in metres;
em
R is the radius, expressed in metres, of the reference circumference;
R′ is the radius, expressed in metres, of the tank circumference at any measuring level;
a is the reference offset, expressed in metres, from the reference circumference to the reference line;
m is the offset, expressed in metres, at the same measuring level as R′.
The tank radius, expressed in metres, at any measuring level, based on all of the horizontal stations is given,
for external measurements, by Equation (4):
()am−
∑
R′′=+Rt− (4)
n
and for internal measurements by Equations (5) and (6):
()ma−
∑
′
RR=−t+ (5)
n
′
′
CR=π2 × (6)
© ISO 2005 – All rights reserved 9
---------------------- Page: 17 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
where
n is the number of horizontal stations;
t′ is the thickness, expressed in metres, of the plate and paint at any measured level;
t is the thickness, expressed in metres, of the plate and paint at the reference level;
C ′ is the internal circumference, expressed in metres, at any measured level.
8.2 Corrections
Assuming that the capacity table has been calculated from internal radii (circumferences), corrections for the
following as described in ISO 7507-1, shall be applied to it:
a) vertical seams, if lap-welded;
b) hydrostatic-head effect;
c) expansion or contraction of the tank shell due to temperature effects;
d) tilt of the tank;
e) mass of any floating roof or cover;
f) deadwood.
8.3 Tank capacity table
Calculate and prepare the tank capacity table as described in ISO 7507-1. Calculations may be undertaken in
radii (in ISO 7507-1 the calculations are based on circumferences).
10 © ISO 2005 – All rights reserved
---------------------- Page: 18 ----------------------
SIST ISO 7507-2:2006
ISO 7507-2:2005(E)
Annex A
(informative)
Tank calibration uncertainties
A.1 Introduction
This annex describes calculations that are used in the estimation of uncertainties of tank calibration when
using optical-reference-line method.
The calculations follow the guidelines set out in the Guide for the expression of uncertainties in measurement
[1]
(GUM) .
A.2 Symbols
The following terms and their units have been used in this annex.
Symbol Description Unit
[1]
k Coverage factor (defined in GUM) —
H Height at which calibration is performed m
j
H Height of the top measured circumference (tank height) m
max
H Height at which the reference circumference is strapped m
ref
∆h Height of the jth section m
j
h Cumulative height of the jth section m
j
uh Standard uncertainty of height (internal) of the tank for section j m
j
uL Standard uncertainty of strapping tape m
st
UL Expanded uncertainty of strapping tape length m
st
rL Resolution of strapping tape reading m
...
МЕЖДУНАРОДНЫЙ ISO
СТАНДАРТ 7507-2
Второе издание
2005-06-01
Нефть и жидкие нефтепродукты.
Калибровка вертикальных
цилиндрических резервуаров.
Часть 2.
Метод оптической реперной линии
Petroleum and liquid petroleum products – Calibration of vertical
cylindrical tanks –
Part 2: Optical reference line method
Ответственность за подготовку русской версии несёт GOST R
(Российская Федерация) в соответствии со статьёй 18.1 Устава ISO
Ссылочный номер
ISO 7507-2:2005(R)
©
ISO 2004
---------------------- Page: 1 ----------------------
ISO 7507-2:2005(R)
Отказ от ответственности при работе в PDF
Настоящий файл PDF может содержать интегрированные шрифты. В соответствии с условиями лицензирования, принятыми
фирмой Adobe, этот файл можно распечатать или смотреть на экране, но его нельзя изменить, пока не будет получена
лицензия на интегрированные шрифты и они не будут установлены на компьютере, на котором ведется редактирование. В
случае загрузки настоящего файла заинтересованные стороны принимают на себя ответственность за соблюдение
лицензионных условий фирмы Adobe. Центральный секретариат ISO не несет никакой ответственности в этом отношении.
Adobe - торговый знак фирмы Adobe Systems Incorporated.
Подробности, относящиеся к программным продуктам, использованные для создания настоящего файла PDF, можно найти в
рубрике General Info файла; параметры создания PDF были оптимизированы для печати. Были приняты во внимание все
меры предосторожности с тем, чтобы обеспечить пригодность настоящего файла для использования комитетами-членами
ISO. В редких случаях возникновения проблемы, связанной со сказанным выше, просьба проинформировать Центральный
секретариат по адресу, приведенному ниже.
ДОКУМЕНТ ОХРАНЯЕТСЯ АВТОРСКИМ ПРАВОМ
© ISO 2005
Все права сохраняются. Если не указано иное, никакую часть настоящей публикации нельзя копировать или использовать в
какой-либо форме или каким-либо электронным или механическим способом, включая фотокопии и микрофильмы, без
предварительного письменного согласия ISO, которое должно быть получено после запроса о разрешении, направленного по
адресу, приведенному ниже, или в комитет-член ISO в стране запрашивающей стороны.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Опубликовано в Швейцарии
ii © ISO 2005 – Все права сохраняются
---------------------- Page: 2 ----------------------
ISO 7507-2:2005(R)
Содержание Страница
Предисловие .iv
Введение .v
1 Область применения .1
2 Нормативные ссылки .1
3 Материалы .1
4 Меры предосторожности .2
5 Оборудование .2
6 Методика .3
6.1 Принцип.3
6.2 Подготовка резервуара .3
6.3 Базовая окружность.4
6.4 Считывания смещения.4
6.5 Калибровка днища резервуара.8
6.6 Другие измерения и данные.8
7 Допуски.9
8 Методика расчета таблицы емкости резервуаров .9
8.1 Внешняя окружность .9
8.2 Поправки .10
8.3 Таблица емкости резервуарa .10
Приложение А (информативное) Неопределённости калибровки резервуаров .11
Библиография.26
© ISO 2005 – Все права сохраняются iii
---------------------- Page: 3 ----------------------
ISO 7507-2:2005(R)
Предисловие
Международная организация по стандартизации (ISO) является всемирной федерацией национальных
организаций по стандартизации (комитетов-членов ISO). Разработка международных стандартов
обычно осуществляется техническими комитетами ISO. Каждый комитет-член, заинтересованный в
деятельности, для которой был создан технический комитет, имеет право быть представленным в этом
комитете. Международные правительственные и неправительственные организации, имеющие связи с
ISO, также принимают участие в работах. Что касается стандартизации в области электротехники, то
ISO работает в тесном сотрудничестве с Международной электротехнической комиссией (IEC).
Проекты международных стандартов разрабатываются в соответствии с правилами, установленными в
Директивах ISO/IEC, Часть 2.
Основная задача технических комитетов заключается в подготовке международных стандартов.
Проекты международных стандартов, принятые техническими комитетами, рассылаются комитетам-
членам на голосование. Их опубликование в качестве международных стандартов требует одобрения
не менее 75 % комитетов-членов, принимающих участие в голосовании.
Следует иметь в виду, что некоторые элементы настоящего международного стандарта могут быть
объектом патентных прав. ISO не может нести ответственность за идентификацию какого-либо одного
или всех патентных прав.
Международный стандарт ISO 7507-2 подготовлен Техническим комитетом ISO/TC 28,
Нефтепродукты и смазочные материалы, Подкомитетом SC 3, Статические измерения нефти.
Настоящая вторая редакция отменяет и заменяет первую редакцию (международный стандарт
ISO 7507-2:1993), которая была подвергнута техническому пересмотру.
Международный стандарт ISO 7507 состоит из следующих частей под общим названием Нефть и
жидкие нефтепродукты. Калибровка вертикальных цилиндрических резервуаров:
− Часть 1. Метод обмера резервуара
− Часть 2. Метод оптической реперной линии
− Часть 3. Метод оптической триангуляции
− Часть 4. Электронно-оптический метод внутреннего измерения расстояний
− Часть 5. Электронно-оптический метод наружного измерения расстояний
iv © ISO 2005 – Все права сохраняются
---------------------- Page: 4 ----------------------
ISO 7507-2:2005(R)
Введение
Настоящая часть международного стандарта ISO 7507 входит в серию международных стандартов по
калибровке резервуаров, включающую следующие международные стандарты:
ISO 4269:2001, Нефть и жидкие нефтепродукты. Калибровка резервуара с помощью измерения
жидкости. Метод приращения с использованием объемных расходомеров
ISO 7507-1:2003, Нефть и жидкие нефтепродукты. Калибровка вертикальных цилиндрических
резервуаров. Часть 1. Метод обмера резервуара
ISO 7507-3:1993, Нефть и жидкие нефтепродукты. Калибровка вертикальных цилиндрических
резервуаров. Часть 3. Метод оптической триангуляции
ISO 7507-4:1995, Нефть и жидкие нефтепродукты. Калибровка вертикальных цилиндрических
резервуаров. Часть 4. Электронно-оптический метод внутреннего измерения расстояний
ISO 7507-5:2000, Нефть и жидкие нефтепродукты. Калибровка вертикальных цилиндрических
резервуаров. Часть 5. Электронно-оптический метод наружного измерения расстояний
ISO 8311:1989, Жидкости углеводородные легкие охлажденные. Калибровка мембранных
резервуаров и независимых призматических судовых резервуаров. Физические измерения
ISO 9091-1:1991, Жидкости углеводородные легкие охлажденные. Калибровка судовых резервуаров
сферической формы. Часть 1. Cтереофотограмметрия
ISO 9091-2:1992, Жидкости углеводородные легкие охлажденные. Калибровка судовых резервуаров
сферической формы. Часть 2. Триангуляционное измерение
ISO 12917-1:2002, Нефть и жидкие нефтепродукты. Калибровка горизонтальных цилиндрических
резервуаров. Часть 1. Ручные методы
ISO 12917-2:2002, Нефть и жидкие нефтепродукты. Калибровка горизонтальных цилиндрических
резервуаров. Часть 2. Метод внутреннего обмера электрооптическими приборами для измерения
расстояний
В настоящей части международного стандарта ISO 7507 описывается метод калибровки вертикальных
цилиндрических резервуаров посредством обмера одной базовой (контрольной) окружности, а затем
определения остающихся окружностей на разных уровнях путем измерения радиальных смещений от
вертикальных оптических реперных линий. Для определения истинных внутренних окружностей
указанные окружности корректируются.
© ISO 2005 – Все права сохраняются v
---------------------- Page: 5 ----------------------
МЕЖДУНАРОДНЫЙ СТАНДАРТ ISO 7507-2:2005(R)
Нефть и жидкие нефтепродукты. Калибровка вертикальных
цилиндрических резервуаров.
Часть 2.
Метод оптической реперной линии
1 Область применения
В настоящей части международного стандарта ISO 7507 описывается метод калибровки резервуаров
диаметром свыше восьми метров с цилиндрическими вертикальными обечайками. В ней представлен
метод определения объема жидкости, содержащейся в резервуаре на откалиброванных уровнях.
ПРИМЕЧАНИЕ Оптические измерения (смещений), необходимые для определения окружностей, могут
проводиться внутри или снаружи резервуара.
Метод, установленный в настоящей части международного стандарта ISO 7507, подходит для
наклонных резервуаров с отклонением до 3 % от вертикали при условии, что в измеренный наклон
вносится поправка, как описано в международном стандарте ISO 7507-1.
Данный метод является альтернативой другим методам, например методу обмера (международный
стандарт ISO 7507-1) и методу оптической триангуляции (международный стандарт ISO 7507-3).
2 Нормативные ссылки
Следующие ссылочные документы являются обязательными при применении данного документа. Для
жестких ссылок применяется только цитированное издание документа. Для плавающих ссылок
необходимо использовать самое последнее издание нормативного ссылочного документа (включая
любые изменения).
ISO 4269:2001, Нефть и жидкие нефтепродукты. Поверка резервуара с помощью измерения
жидкости. Метод приращения с использованием объемных расходомеров
ISO 7507-1:2003, Нефть и жидкие нефтепродукты. Калибровка вертикальных цилиндрических
резервуаров. Часть 1. Метод обмера резервуара
3 Материалы
Для целей настоящего документа используются термины и определения, представленные в
международном стандарте ISO 7507-1, а также следующие термины и определения.
3.1
оптическая реперная линия
optical – reference – line
вертикальный оптический луч (виртуальный), создаваемый оптическим устройством в заданном
положении
© ISO 2005 – Все права сохраняются 1
---------------------- Page: 6 ----------------------
ISO 7507-2:2005(R)
3.2
магнитная тележка
magnetic trolley
механическое устройство, которое может перемещаться вверх и вниз по стенке обшивки резервуара
для измерения отклонений обшивки относительно оптической реперной линии с использованием
горизонтальной шкалы, установленной на тележке
3.3
позиция
station
положение, в котором устанавливаются оптическое устройство и магнитная тележка для проведения
оптических измерений
3.4
горизонтальная позиция
horizontal station
позиция, которую занимает оптическое устройство, когда оно перемещается вокруг окружности
резервуара
3.5
вертикальная позиция
vertical station
позиция, в которой магнитная тележка располагается вдоль стенки обшивки резервуара
3.6
базовая окружность
reference circumference
окружность, измеряемая на обечайке днища, которая является основой для последующих вычислений
3.7
контрольное смещение
reference offset
расстояние стенки обшивки (в каждой горизонтальной позиции) от оптической реперной линии,
измеряемое на обечайке днища, где определяется базовая окружность
4 Меры предосторожности
К настоящей части международного стандарта ISO 7507 должны применяться общие меры предосторожности, а
также меры предосторожности, установленные в международном стандарте ISO 7507-1.
5 Оборудование
5.1 Оборудование для обмера резервуара, как установлено в международном стандарте ISO 7507-1:
− обвязочные ленты;
− пружинные весы;
− шаговое устройство;
− захват Литтлджона;
− замерная лента и замерный груз.
5.2 Устройство, устанавливающее оптическую реперную линию, например, точный оптический
отвес, точный нивелир с пентапризмой или точный теодолит с пентапризмой.
ПРИМЕЧАНИЕ 1 Указанные выше оптические приборы оснащены средствами крепления либо к штативу,
магнитному кронштейну, либо к другим устойчивым опорам.
Прибор, при установке его на опору и выравнивании либо вручную с использованием пузырькового
уровня, либо автоматически, если имеется автоматический нивелир, должен устанавливать
вертикальную линию визирования.
Прибор должен иметь короткое фокусное расстояние с тем, чтобы, когда он устанавливается на
2 © ISO 2005 – Все права сохраняются
---------------------- Page: 7 ----------------------
ISO 7507-2:2005(R)
рабочей высоте, его можно было бы сфокусировать на шкале на уровне контрольного обмера.
Прибор должен иметь разрешение не менее 1:20 000 и оснащаться телескопом с увеличением не
менее 20. Пентапризма, используемая с нивелиром или теодолитом, не должна вводить существенные
коллимационные ошибки.
ПРИМЕЧАНИЕ 2 Оптические отвесы могут оснащаться одной оптической системой, например, зенитный отвес,
двойной оптической системой или одной суперпозиционной оптической системой, устанавливающей линии
визирования, направленные как вверх, так и вниз, например, надирный/зенитный отвес. Предпочтительно, чтобы
отвес не имел подвижных элементов в своей оптической системе, например, зеркал или пентапризм, что
позволяет обеспечить стабильность линии визирования.
5.3 Магнитная тележка надежной конструкции. Её конструкция должна включать следующие элементы.
a) Магнит (магниты) должен (должны) быть достаточно мощным (мощными) с тем, чтобы тележка
не теряла контакта с обшивкой резервуара при сильном ветре или когда должны преодолеваться
муфтовые соединения или когда имеются толстые слои краски или осадок.
b) Магнит (магниты) должен (должны) регулироваться по высоте так, чтобы зазор между поверхностями
магнита и резервуаром мог изменяться в зависимости от конструкции резервуара и условий.
c) Шнур или стальной трос должен прикрепляться к тележке для её подъема или опускания от
крыши резервуара или через систему шкивов от поверхности земли.
d) Градуированная шкала должна надежно прикрепляться к тележке на её центральной линии.
Если тележка находится в рабочем режиме, шкала должна располагаться либо перпендикулярно
к обшивке резервуара, либо горизонтально.
e) Шкала должна прикрепляться к тележке по возможности вблизи центральной линии оси с тем,
чтобы уменьшить ошибки, вызываемые деформациями резервуара.
ПРИМЕЧАНИЕ Тележки, не являющиеся магнитными, могут использоваться для поддержания контакта с
обшивкой резервуара.
5.4 Градуированная шкала, изготавливаемая из стали, с делениями в миллиметрах. По возможности
длина шкалы должна быть короткой и должна определяться расстоянием от поверхности резервуара,
на котором может быть установлено оптическое оборудование. Шкала должна быть откалибрована с
использованием стандартных методов и стандартных эталонных устройств.
6 Методика
6.1 Принцип
Метод калибровки основывается на точном измерении базовой окружности с использованием
откалиброванной измерительной ленты, располагаемой на одном уровне на доступной обечайке без
препятствий. Повторные измерения, согласующиеся в пределах установленных допусков, проводятся
для исключения систематической ошибки при измерении окружностей. Длина окружностей
вычисляется по базовой окружности и результатам измерений смещений на установленных уровнях и
на базовой окружности. Эти смещения являются мерой отклонения стенки резервуара. Они
измеряются для установленного числа вертикальных оптических реперных линий, отстоящих друг от
друга на одинаковом расстоянии вокруг резервуара.
ПРИМЕЧАНИЕ На Рисунках 1 – 3 приведены соответствующие примеры.
6.2 Подготовка резервуара
При использовании новых резервуаров или отремонтированных резервуаров наполните резервуар до
его обычной рабочей емкости как минимум один раз и перед проведением калибровки дайте ему
отстояться в течение не менее 24 ч.
Если резервуар калибруется с жидкостью, находящейся в нем, запишите глубину, температуру и плотность
жидкости во время проведения калибровки. В процессе калибровки не перекачивайте жидкость.
При использовании резервуаров с плавающей крышей, когда измерения смещения производятся
© ISO 2005 – Все права сохраняются 3
---------------------- Page: 8 ----------------------
ISO 7507-2:2005(R)
внутри резервуара, крыша должна находиться в самом нижнем положении, опираясь на ножки.
6.3 Базовая окружность
Базовая окружность непосредственно влияет на калибруемый объем всего резервуара. Поэтому её
необходимо измерять с возможной наибольшей точностью.
Определите базовую окружность, используя контрольный метод, описанный в международном
стандарте ISO 7507-1, и выполните следующие действия.
a) Проведите многократные измерения базовой окружности либо до начала оптических считываний,
либо после их завершения. Если результаты первых трех последовательных измерений
согласуются друг с другом в пределах допусков, установленных в Разделе 7, вычислите их
среднее значение как значение длины базовой окружности и их стандартное отклонение как
стандартную неопределённость. Если эти результаты не согласуются в пределах допусков,
установленных в Разделе 7, повторяйте измерения до тех пор, пока два стандартных отклонения
от среднего значения измерений не будут меньше половины допусков, установленных в разделе
7. Используйте среднее значение как измеренное значение длины базовой окружности, а
стандартное отклонение – как стандартную. Неопределённость. Используйте стандартные
методики для устранения очевидных выбросов.
b) Проведите измерения базовой окружности в положении, в котором рабочие условия обеспечивают
надежные измерения и которое находится в пределах фокусного расстояния оптического прибора.
Обмерьте резервуар, осуществив визирование на одном из следующих уровней:
1) на 1/4 высоты обечайки над нижним горизонтальным стыком,
2) на 1/4 высоты обечайки под верхним горизонтальным стыком
и повторите измерения для получения согласованных результатов в пределах допусков,
установленных в Разделе 7.
6.4 Считывания смещения
6.4.1 Установите устройство, создающее оптическую реперную линию (5.2), магнитную тележку
(5.3) и градуированную шкалу (5.4) последовательно в горизонтальные позиции (см. 6.4.2),
располагаемые вокруг резервуара на одинаковом расстоянии друг от друга, по возможности ближе к
стенке резервуара. Базовые линии должны выбираться так, чтобы тележка не перемещалась над
вертикальным стыком или его сварным швом.
6.4.2 Минимальное число горизонтальных позиций должно быть таким, как установлено в Таблице 1.
Таблица 1 — Минимальное число горизонтальных позиций
Окружность Минимальное число горизонтальных позиций
м
≤ 50 10
> 50, ≤ 100 12
> 100, ≤ 150 16
> 150, ≤ 200 20
> 200, ≤ 250 24
> 250, ≤ 300 30
> 300 36
ПРИМЕЧАНИЕ 1 Число горизонтальных позиций, деленное на число листов в сегментах резервуара, не
должно равняться целому числу (например, 1, 2, 3 и т. д.) с тем, чтобы исключить систематические погрешности.
ПРИМЕЧАНИЕ 2 Использование минимального числа горизонтальных позиций, в частности, в случае небольших резервуаров,
может привести к неопределённостям, превышающим допустимые значения.
4 © ISO 2005 – Все права сохраняются
---------------------- Page: 9 ----------------------
ISO 7507-2:2005(R)
Размеры в миллиметрах
Обозначение
1 – 7 горизонтальные уровни 11 градуированная шкала
8 оптическая реперная линия 12 сварной шов (горизонтальный)
9 сварной шов (вертикальный) 13 базовая окружность, взятая вблизи положения 1
10 магнитная тележка 14 Оптическое оборудование
a) Вид спереди резервуара
b) Вид горизонтальных позиций сверху
ПРИМЕЧАНИЕ Горизонтальные позиции обозначаются как А – K на виде сверху (см. также 6.4.2). Из них
только позиции Е и F показаны на виде резервуара спереди.
Рисунок 1—Оптические измерения смещений от стенки резервуара (типичный случай)
© ISO 2005 – Все права сохраняются 5
---------------------- Page: 10 ----------------------
ISO 7507-2:2005(R)
а) Смещение центральной линии b) Внешнее смещение с) Внутреннее смещение
Обозначение
1 оптическая реперная линия
2 центральная линия резервуара
Внешняя базовая окружность = С
em
Внешний базовый радиус (обечайка днища) = С /2π = R
em
Внешний радиус второй обечайки = R' , R'
1 2
Значения толщины обечаек = t , t и т.д.
1 2
Контрольное смещение = a
Базовый радиус = R
Смещения отдельных обечаек = m , m , и т. д.
1 2
Внутренний базовый радиус = R – t = C /2π - t = R
1 em 1 1
Внутренний радиус, вторая обечайка, днище = R'
1i
Внутренний радиус, вторая обечайка, верхняя часть = R'
2i
Рисунок 2 — Определение внутреннего радиуса по смещениям относительно внешней
оптической реперной линии
6 © ISO 2005 – Все права сохраняются
---------------------- Page: 11 ----------------------
ISO 7507-2:2005(R)
а) Смещение центральной линии b) Внешнее смещение с) Внутреннее смещение
Обозначение
1 оптическая реперная линия
2 центральная линия резервуара
Внешняя базовая окружность = С
em
Внешний базовый радиус (обечайка днища) = С /2π = R
em
Внешний радиус второй обечайки = R' , R'
1 2
Значения толщины обечаек = t , t и т.д.
1 2
Контрольное смещение = a
Базовый радиус = R
Смещения отдельных обечаек = m , m , и т. д.
1 2
Внутренний базовый радиус
= R – t = C /2π - t = R
1 em 1 1
Внутренний радиус, вторая обечайка, днище = R'
1i
Внутренний радиус, вторая обечайка, верхняя = R'
2i
часть
Рисунок 3 — Определение внутреннего радиуса по смещениям относительно внутренней
оптической реперной линии
6.4.3 Перед снятием показаний проверьте вертикальность оптической реперной линии путем
поворота оптического прибора в первой горизонтальной позиции на 180°, при этом разность между
двумя показаниями в диаметрально противоположных позициях должна находиться в пределах 1:20 000.
Кроме того, проверьте вертикальность оптической реперной линии в каждой позиции по завершению
снятия показаний. Если вертикальность не сохранилась, повторите процедуру калибровки в этой
позиции.
6.4.4 Проведите не менее двух измерений смещений от вертикали в расчете на обечайку в каждом
горизонтальном положении с прицеливанием на 1/4 высоты обечайки над нижним горизонтальным
швом и 1/4 высоты обечайки под верхним горизонтальным швом. Снимите показания с градуированной
шкалы с точностью до ближайшего миллиметра.
6.4.5 Во всех горизонтальных позициях измерьте контрольное смещение, а затем проведите
измерения последовательно в вертикальных позициях на каждой обечайке при перемещении тележки
вверх по стенке резервуара. После измерения последнего смещения на верхней обечайке
переместите тележку вниз к обечайке днища и повторно измерьте контрольное смещение. Начальное
и конечное контрольные смещения должны согласовываться в пределах двух миллиметров. В
© ISO 2005 – Все права сохраняются 7
---------------------- Page: 12 ----------------------
ISO 7507-2:2005(R)
дальнейших расчетах используйте среднее значение начального и конечного смещений.
Если согласие не достигнуто, повторите измерения вертикального смещения в этом горизонтальном
положении.
6.5 Калибровка днища резервуара
Откалибруйте днище резервуара путем заполнения его измеренными количествами нелетучей
жидкости (предпочтительно чистой водой), как показано в международном стандарте ISO 4269, до
минимального уровня, полностью покрывая водой днище, погружая замерную пластинку и устраняя
влияние деформаций днища. Далее перекачивайте измеренные количества жидкости в резервуар до
тех пор, пока наивысшая точка его днища не покроется жидкостью, а уровень жидкости не превысит
наинизшую точку резервуара, где будет выполняться калибровка путем обмера (например, в
положении измерений смещения или в положении базовой окружности). Альтернативно, откалибруйте
днище резервуара путем физического обследования с использованием контрольной плоскости для
определения формы днища, как установлено в международном стандарте ISO 7507-1.
6.6 Другие измерения и данные
6.6.1 Определите, используя калибровочное оборудование, и обработайте следующие данные, как
описано в международном стандарте ISO 7507-1:
а) толщина листов и красочного покрытия;
b) значения высоты обечаек;
c) плотность и рабочая температура жидкости, хранящейся в резервуаре;
d) температура окружающей среды и температура жидкости во время проведения измерений;
e) максимальная высота наполнения;
f) объем, занимаемый конструкциями внутри резервуара;
g) количество, ширина и толщина вертикальных швов или наплывов;
h) наклон резервуара, определяемый отклонениями отвеса;
i) форма, высота площадки и присоединенная масса в воздухе плавающей крыши или крышки.
ПРИМЕЧАНИЕ Знание среднего значения и диапазона температур обшивки резервуара необходимо для
анализа неопределённости (см. Приложение А).
6.6.2 Необходимо относить каждую глубину резервуара к замерной точке, которая может
находиться в разных положениях от реперной точки, используемой для калибровки резервуара
(например, точка на углу днища). Определите разность уровней между реперной точкой и замерной
точкой либо методами обычного обследования, либо другими средствами и запишите её значение.
6.6.3 Измерьте полную высоту реперной точки на каждом замерном люке (верхняя реперная точка)
над замерной точкой, используя замерную ленту и замерный груз, как установлено в международном
стандарте ISO 7507-1. Запишите значение полной высоты с точностью до ближайшего миллиметра и
постоянно отмечайте её на резервуаре вблизи замерного люка.
6.6.4 По возможности сравните результаты измерений с соответствующими размерами,
показанными на чертежах, и проверьте результаты измерений, обнаруживающие существенное
расхождение.
8 © ISO 2005 – Все права сохраняются
---------------------- Page: 13 ----------------------
ISO 7507-2:2005(R)
7 Допуски
Измерения базовой окружности должны согласовываться в пределах абсолютных допусков,
приведенных в Таблице 2.
Таблица 2 — Абсолютные допуски на измерения окружности
Измерения окружности Абсолютный допуск
м мм
≤ 25 2
> 25, ≤ 50 3
> 50, ≤ 100 5
> 100, ≤ 200 6
> 200 8
8 Методика расчета таблицы емкости резервуаров
8.1 Внешняя окружность
Рассчитайте внешнюю окружность с использованием считанных смещений и базовой окружности по
следующим формулам:
C
em
R= (1)
2π
′
Ra+=R+m (2)
′
RR=+()a−m (3)
где
С длина базовой окружности, выражаемая в метрах;
em
R радиус базовой окружности, выражаемый в метрах;
R′ радиус окружности резервуара на любом измерительном уровне, выражаемый в метрах;
a контрольное смещение от базовой окружности до реперной линии, выражаемое в метрах;
m смещение на том же уровне, что и R', выражаемое в метрах.
Радиус резервуара на любом измерительном уровне, выражаемый в метрах и полученный с
использованием всех горизонтальных позиций, определяется путем наружных измерений по формуле:
()am−
∑
RR′′=+ −t (4)
n
а для внутренних измерений - по формулам (5) и (6):
()ma−
∑
′
RR=−t+ (5)
n
′
′
CR=π2× (6)
© ISO 2005 – Все права сохраняются 9
---------------------- Page: 14 ----------------------
ISO 7507-2:2005(R)
где
n количество горизонтальных позиций;
t' толщина листа и красочного покрытия на любом измеряемом уровне, выражаемая в
метрах;
t толщина листа и красочного покрытия на контрольном уровне, выражаемая в метрах;
C' длина внутренней окружности на любом измеряемом уровне, выражаемая в метрах.
8.2 Поправки
В предположении, что таблица емкостей резервуара была рассчитана по внутренним радиусам
(окружностям), в неё в соответствии с международным стандартом ISO 7507-1 должны быть внесены
поправки, связанные с:
a) вертикальными швами (при сварке внахлестку);
b) влиянием гидростатического напора;
c) расширением или сжатием обшивки резервуара вследствие тепловых эффектов;
d) наклоном резервуара;
e) массой плавающей крыши или крышки;
f) объемом, занимаемым конструкциями внутри резервуара.
8.3 Таблица емкости резервуарa
Рассчитайте и составьте таблицу емкости резервуара, ка
...
INTERNATIONAL ISO
STANDARD 7507-2
Second edition
2005-06-01
Petroleum and liquid petroleum
products — Calibration of vertical
cylindrical tanks —
Part 2:
Optical-reference-line method
Pétrole et produits pétroliers liquides — Jaugeage des réservoirs
cylindriques verticaux —
Partie 2: Méthode par ligne de référence optique
Reference number
ISO 7507-2:2005(E)
©
ISO 2005
---------------------- Page: 1 ----------------------
ISO 7507-2:2005(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2005
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2005 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 7507-2:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Precautions .2
5 Equipment .2
6 Procedure .3
6.1 Principle.3
6.2 Preparation of the tank.3
6.3 Reference circumference.3
6.4 Offset readings.4
6.5 Tank bottom calibration .8
6.6 Other measurements and data.8
7 Tolerances .9
8 Tank capacity calculation procedure .9
8.1 Outside circumference.9
8.2 Corrections.10
8.3 Tank capacity table.10
Annex A (informative) Tank calibration uncertainties.11
Bibliography .26
© ISO 2005 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 7507-2:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7507-2 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants,
Subcommittee SC 3, Static petroleum measurement.
This second edition cancels and replaces the first edition (ISO 7507-2:1993), which has been technically
revised.
ISO 7507 consists of the following parts, under the general title Petroleum and liquid petroleum products —
Calibration of vertical cylindrical tanks:
Part 1: Strapping method
Part 2: Optical-reference-line method
Part 3: Optical-triangulation method
Part 4: Internal electro-optical distance-ranging method
Part 5: External electro-optical distance-ranging method
iv © ISO 2005 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 7507-2:2005(E)
Introduction
This part of ISO 7507 forms part of a series on tank calibration, including the following:
ISO 4269:2001, Petroleum and liquid petroleum products — Tank calibration by liquid measurement —
Incremental method using volumetric meters
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 1: Strapping method
ISO 7507-3:1993, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 3: Optical-triangulation method
ISO 7507-4:1995, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 4: Internal electro-optical distance-ranging method
ISO 7507-5:2000, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 5: External electro-optical distance-ranging method
ISO 8311:1989, Refrigerated light hydrocarbon fluids — Calibration of membrane tanks and independent
prismatic tanks in ships — Physical measurement
ISO 9091-1:1991, Refrigerated light hydrocarbon fluids — Calibration of spherical tanks in ships — Part 1:
Stereo-photogrammetry
ISO 9091-2:1992, Refrigerated light hydrocarbon fluids — Calibration of spherical tanks in ships — Part 2:
Triangulation measurement
ISO 12917-1:2002, Petroleum and liquid petroleum products — Calibration of horizontal cylindrical tanks —
Part 1: Manual methods
ISO 12917-2: 2002, Petroleum and liquid petroleum products — Calibration of horizontal cylindrical tanks —
Part 2: Internal electro-optical distance-ranging method
This part of ISO 7507 describes a method for the calibration of vertical cylindrical tanks by measurement of
one reference circumference by strapping and then determining the remaining circumferences at different
levels from measurements of radial offsets from vertical optical-reference-lines. These circumferences are
corrected to give the true internal circumferences.
© ISO 2005 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 7507-2:2005(E)
Petroleum and liquid petroleum products — Calibration of
vertical cylindrical tanks —
Part 2:
Optical-reference-line method
1 Scope
This part of ISO 7507 specifies a method for the calibration of tanks above eight metres in diameter with
cylindrical courses that are substantially vertical. It provides a method for determining the volumetric quantity
contained within a tank at gauged liquid levels.
NOTE The optical (offset) measurements required to determine the circumferences can be taken internally or
externally.
The method specified in this part of ISO 7507 is suitable for tilted tanks with up to 3 % deviation from the
vertical provided that a correction is applied for the measurement tilt, as described in ISO 7507-1.
This method is an alternative to other methods such as strapping (ISO 7507-1) and the optical-triangulation
method (ISO 7507-3).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 4269:2001, Petroleum and liquid petroleum products — Tank calibration by liquid measurement —
Incremental method using volumetric meters
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 1: Strapping method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7507-1 and the following apply.
3.1
optical-reference-line
vertical optical ray (virtual) that is established using the optical device at a given location
3.2
magnetic trolley
mechanical device that can be traversed up or down the tank shell wall to measure deviations in the tank shell
relative to the optical-reference-line using a horizontal scale that is mounted on the trolley
© ISO 2005 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 7507-2:2005(E)
3.3
station
location where the optical device and the magnetic trolley are placed for optical measurements
3.4
horizontal station
station where the optical device is located as it is moved around the tank circumference
3.5
vertical station
station where the magnetic trolley is located along the tank shell wall
3.6
reference circumference
circumference measured at the bottom course that forms the basis for subsequent computations
3.7
reference offset
distance of the shell wall (at each horizontal station) from the optical-reference-line measured at the bottom
course where the reference circumference is measured
4 Precautions
The general precautions and safety precautions specified in ISO 7507-1 shall apply to this part of ISO 7507.
5 Equipment
5.1 Equipment for tank strapping, as follows, as specified in ISO 7507-1:
strapping tapes;
spring balance;
step-over;
littlejohn grip;
dip-tape and dip-weight.
5.2 Optical-reference-line device, such as a precision optical plummet, a precision engineer’s level with a
pentaprism attachment, or a precision engineer’s theodolite with a pentaprism attachment.
NOTE 1 These are optical instruments with a means of attachment to either a tripod, magnetic bracket or other stable
means of support.
The instrument, when set on its support and levelled, either manually using bubble vials or automatically if an
automatic levelling device is fitted, shall be capable of giving a vertical line of sight.
The instrument should preferably be of short focal length so that, when set up at a practical working height, it
can be focused on the scale at the reference strapping level.
The instrument shall have a resolution of at least 1:20 000 and be equipped with a telescope with a
magnification of not less than 20. The pentaprism attachment for use with an engineer’s level or engineer’s
theodolite shall not introduce any significant collimation errors.
2 © ISO 2005 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 7507-2:2005(E)
NOTE 2 Optical plummets can be fitted with a single optical train, i.e. a zenith plummet, a double optical train or a
single superimposed optical train giving both upward and downward lines of sight, i.e. a nadir/zenith plummet. It is
preferable that the plummet does not have any movable elements in its optical train, such as mirrors or pentaprisms, to
ensure stability of the line of sight.
5.3 Magnetic trolley, of robust construction. Its design shall include the following features.
a) The magnet(s) shall be of sufficient power to ensure that the trolley does not lose contact with the tank
shell in conditions of high wind or when ring joints have to be negotiated or when there are heavy layers
of paint or scale.
b) The magnet(s) shall be adjustable for height so that the clearance between the magnet faces and the
tank may be varied to suit the tank construction and condition.
c) A cord or wire cable shall be attached to enable it to be raised or lowered from the tank roof or, via a
pulley system, from ground level.
d) A graduated scale shall be attached securely to the trolley at its centreline. When the trolley is in its
operational mode, the scale shall be either perpendicular to the tank shell or horizontal.
e) The scale shall be attached to the trolley as closely as possible to the centreline of an axis in order to
reduce errors caused by deformations in the tank.
NOTE Trolleys that are not magnetic can be used to maintain contact with the tank shell.
5.4 Graduated scale, made of steel and marked in millimetre increments. The length of the scale shall be
as short as is practicable and shall be determined by the distance at which the optical equipment can be set
up from the tank side. The scale shall be calibrated using standard methods and standard reference devices.
6 Procedure
6.1 Principle
This calibration method is based on the accurate measurement of a reference circumference using a
calibrated measuring tape at one level on an accessible, non-obstructed course. Repeat measurements
agreeing within specified tolerances are made to avoid any systematic error in the derived circumferences.
The derived circumferences are calculated from the reference circumference, and measurements of offsets
taken at the specified levels and at the reference circumference. These offsets are a measure of the deviation
of the tank wall. They are measured at a specified number of vertical, optical-reference-lines spaced equally
around the tank.
NOTE For examples see Figures 1 to 3.
6.2 Preparation of the tank
For new tanks or for tanks after repair, fill the tank to its normal working capacity at least once and allow it to
stand for at least 24 h prior to calibration.
If the tank is calibrated with liquid in it, record the depth, temperature and density of the liquid at the time of
calibration. Do not make transfers of liquid during the calibration.
For floating-roof tanks where offset measurements may be taken internally, the roof shall be in its lowest
position, resting on the legs.
6.3 Reference circumference
Reference circumference has a direct impact on the calibrated volume of entire tank. It, therefore, shall be
measured as accurately as possible.
© ISO 2005 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 7507-2:2005(E)
Determine the reference circumference using the reference method described in ISO 7507-1 and the following.
a) Take multiple measurements of the reference circumference either prior to the commencement or after
the completion of the optical readings. If the first three consecutive measurements agree within the
tolerances specified in Clause 7, take their mean average as the reference circumference and their
standard deviation as the standard uncertainty. If they do not agree within the tolerances specified in
Clause 7, repeat the measurements until two standard deviations of the mean of all measurements is less
than the half of the tolerances specified in Clause 7. Use the mean as the measured reference
circumference and the standard deviation as the standard uncertainty. Use standard procedures to
eliminate obvious outliers.
b) Take the measurement of the reference circumference at a position where work conditions allow reliable
measurements, and which is within the focal range of the optical instrument. Strap the tank, aiming at one
of the following levels:
1) 1/4 of the course height above the lower horizontal seam,
2) 1/4 of the course height below the upper horizontal seam;
and repeat the measurement to achieve measurements agreeing within the tolerances specified in
Clause 7.
6.4 Offset readings
6.4.1 Set up the optical-reference-line device (5.2), magnetic trolley (5.3) and graduated scale (5.4)
successively at the horizontal stations (see 6.4.2) that are equally spaced around the tank, as close as
possible to the tank wall. Reference lines shall be chosen such that the trolley does not run over a vertical
seam or its weld.
6.4.2 The minimum number of horizontal stations shall be as given in Table 1.
Table 1 — Minimum number of horizontal stations
Circumference Minimum number of horizontal stations
m
u 50 10
> 50, u 100 12
> 100, u 150 16
> 150, u 200 20
> 200, u 250 24
> 250, u 300 30
> 300 36
NOTE 1 The number of horizontal stations divided by the number of plates in tank segments
should not be equal to an integer (e.g. 1, 2, 3, etc.) in order to avoid systematic errors.
NOTE 2 Using the minimum number of horizontal stations, especially for smaller tanks, can
lead to larger-than-acceptable uncertainties.
4 © ISO 2005 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 7507-2:2005(E)
Dimensions in millimetres
Key
1 to 7 horizontal levels 11 graduated scale
8 optical-reference-line 12 weld seam (horizontal)
9 weld seam (vertical) 13 reference circumference taken close to location 1
10 magnetic trolley 14 optical equipment
a) Tank elevation
b) Plan of horizontal stations
NOTE The horizontal stations are designated A to K in the plan view (see also 6.4.2). Of these, only E and F are
shown in the elevation.
Figure 1 — Optical measurement of offsets from tank wall (typical case)
© ISO 2005 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 7507-2:2005(E)
a) Centreline flush b) Outside flush c) Inside flush
Key
1 optical-reference-line
2 tank centreline
External reference circumference = C
em
External reference radius (bottom course) = C /2π = R
em
Outer radius of second course = R′ , R′ ,
1 2
Course thicknesses = t , t , etc.
1 2
Reference offset = a
Reference radius = R
Individual course offsets = m , m , etc.
1 2
Internal reference radius = R – t = C /2π – t = R
1 em 1 1
Internal radius, second course, bottom = R′
1i
Internal radius, second course, top = R′
2i
Figure 2 — Determination of internal radius from offsets to external optical-reference-line
6 © ISO 2005 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 7507-2:2005(E)
a) Centreline flush b) Outside flush c) Inside flush
Key
1 optical-reference-line
2 tank centreline
External reference circumference = C
em
External reference radius (bottom course) = C /2π = R
em
Outer radius of second course = R′ , R′ ,
1 2
Course thicknesses = t , t , etc.
1 2
Reference offset = a
Reference radius = R
Individual course offsets = m , m , etc.
1 2
Internal reference radius = R – t = C /2π – t = R
1 em 1 1
Internal radius, second course, bottom = R′
1i
Internal radius, second course, top = R′
2i
Figure 3 — Determination of internal radius from offsets to internal optical-reference-line
6.4.3 Verify the verticality of the optical-reference-line prior to the commencement of readings by turning the
optical instrument at the first horizontal station through 180°, whereby the difference between the two readings
of the diametrically opposite positions shall be within 1 in 20 000. Also, verify the verticality of the optical-
reference-line at each station at the completion of the readings. If verticality has not been maintained, repeat
the calibration procedure at this station.
6.4.4 Take a minimum of two measurements of offsets from vertical per course at each horizontal station,
aiming at 1/4 of course height above the lower horizontal seam and at 1/4 of course height below the upper
horizontal seam. Read the graduated scale to the nearest millimetre.
6.4.5 At all horizontal stations, measure the reference offset and then take offset measurements
progressively at vertical stations on each course as the trolley is raised up the tank wall. After the last offset
measurement has been taken on the top course, lower the trolley to the bottom course and repeat the
reference offset. The initial and final reference offset readings shall agree to within two millimetres. In further
calculations, use the mean average of the initial and the final offset readings.
If agreement is not obtained, repeat vertical offset measurements at this horizontal station.
© ISO 2005 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO 7507-2:2005(E)
6.5 Tank bottom calibration
Calibrate the tank bottom, preferably by filling with measured quantities of a non-volatile liquid (preferably
clean water), as illustrated in ISO 4269, to a minimum level that covers the bottom completely, immersing the
dip-plate and eliminating the effect of bottom deformations. Transfer further measured quantities of liquid into
the tank until the highest point of the tank bottom is covered and the liquid level is higher than the lowest point
on the tank that will be calibrated by strapping (for example the offset measurement location or the reference
circumference location as appropriate). Alternatively, calibrate the tank bottom by a physical survey using a
reference plane to determine the shape of the bottom as specified in ISO 7507-1.
6.6 Other measurements and data
6.6.1 Determine, using calibrated equipment, and process the following data as described in ISO 7507-1:
a) plate and paint thickness;
b) height of the courses;
c) density and working temperature of the liquid to be stored in the tank;
d) ambient temperature and the temperature of the liquid at the time of measurement;
e) maximum filling height;
f) deadwood;
g) number, width and thickness of any vertical welds or overlaps;
h) tilt of the tank as shown by the plumb line deviations;
i) shape, landing height and apparent mass in air of any floating roof or cover.
NOTE Average mean value and a range of tank shell temperatures are required for uncertainty analysis (see
Annex A).
6.6.2 It is necessary to refer each tank dip to the dip-point, which may be in a different position from the
datum-point used for the purpose of tank calibration (e.g. a point on the bottom angle). Determine any
difference in level between the datum-point and dip-point, either by normal surveying methods or by other
means, and record it.
6.6.3 Measure the overall height of the reference point on each dip-hatch (upper reference point) above the
dip-point using the dip-tape and dip-weight as specified in ISO 7507-1. Record this overall height, to the
nearest millimetre and permanently mark it on the tank adjacent to that dip-hatch.
6.6.4 If possible, compare measurements with corresponding dimensions shown in the drawings and verify
any measurement that shows a significant discrepancy.
8 © ISO 2005 – All rights reserved
---------------------- Page: 13 ----------------------
ISO 7507-2:2005(E)
7 Tolerances
Reference circumference measurements shall agree within the absolute tolerances given in Table 2.
Table 2 — Absolute tolerances on circumferential measurements
Circumferential measurement Absolute tolerance
m mm
u 25 2
> 25, u 50 3
> 50, u 100 5
> 100, u 200 6
> 200 8
8 Tank capacity table calculation procedure
8.1 Outside circumference
Calculate the outside circumference from offset readings and the reference circumference by using
Equations (1) to (3):
C
em
R = (1)
2π
R+=aR′+m (2)
R′=+Ra−m (3)
( )
where
C is the reference circumference, expressed in metres;
em
R is the radius, expressed in metres, of the reference circumference;
R′ is the radius, expressed in metres, of the tank circumference at any measuring level;
a is the reference offset, expressed in metres, from the reference circumference to the reference line;
m is the offset, expressed in metres, at the same measuring level as R′.
The tank radius, expressed in metres, at any measuring level, based on all of the horizontal stations is given,
for external measurements, by Equation (4):
()am−
∑
R′′=+Rt− (4)
n
and for internal measurements by Equations (5) and (6):
()ma−
∑
′
RR=−t+ (5)
n
′
′
CR=π2 × (6)
© ISO 2005 – All rights reserved 9
---------------------- Page: 14 ----------------------
ISO 7507-2:2005(E)
where
n is the number of horizontal stations;
t′ is the thickness, expressed in metres, of the plate and paint at any measured level;
t is the thickness, expressed in metres, of the plate and paint at the reference level;
C ′ is the internal circumference, expressed in metres, at any measured level.
8.2 Corrections
Assuming that the capacity table has been calculated from internal radii (circumferences), corrections for the
following as described in ISO 7507-1, shall be applied to it:
a) vertical seams, if lap-welded;
b) hydrostatic-head effect;
c) expansion or contraction of the tank shell due to temperature effects;
d) tilt of the tank;
e) mass of any floating roof or cover;
f) deadwood.
8.3 Tank capacity table
Calculate and prepare the tank capacity table as described in ISO 7507-1. Calculations may be undertaken in
radii (in ISO 7507-1 the calculations are based on circumferences).
10 © ISO 2005 – All rights reserved
---------------------- Page: 15 ----------------------
ISO 7507-2:2005(E)
Annex A
(informative)
Tank calibration uncertainties
A.1 Introduction
This annex describes calculations that are used in the estimation of uncertainties of tank calibration when
using optical-reference-line method.
The calculations follow the guidelines set out in the Guide for the expression of uncertainties in measurement
[1]
(GUM) .
A.2 Symbols
The following terms and their units have been used in this annex.
Symbol Description Unit
[1]
k Coverage factor (defined in GUM) —
H Height at which calibration is performed m
j
H Height of the top measured circumference (tank height) m
max
H Height at which the reference circumference is strapped m
ref
∆h Height of the jth section m
j
h Cumulative height of the jth section m
j
uh Standard uncertainty of height (internal) of the tank for section j m
j
uL Standard uncertainty of strapping tape m
st
UL Expanded uncertainty of strapping tape length m
st
rL Resolution of strapping tape reading m
tr
uL Standard uncertainty of strapping tape reading m
tr
tL Tolerance of strapping tape tension and position m
tp
uL Standard uncertainty of strapping tape tension and position m
tp
eL Maximum error of alignment m
ta
uL Standard uncertainty of strapping tape alignment m
ta
uL Standard deviation of mean of multiple strapping measurements m
m
C Measured external reference circumference m
em
uC Standard uncertainty of measured external reference circumference m
em
uR Standard uncertainty of external (strapped) reference radius the tank m
ext
uR Standard uncertainty of internal reference radius the tank m
int
uR Standard uncertainty of any internal radius of the tank corrected for temperature m
it
uδR Standard uncertainty of radius correction for deformation due to hydrostatic head m
h
© ISO 2005 – All rights reserved 11
---------------------- Page: 16 ----------------------
ISO 7507-2:2005(E)
Symbol Description Unit
uR Standard uncertainty of any internal radius of the tank m
i
t Maximum deviation from vertical of the reference line %
v
t Maximum error of reading of the scale on the magnetic trolley m
r
Standard uncertainty of the difference of offsets measured at height H and H
ji ref
uma m
ji
respectively
wt Maximum uncertainty of thickness of the tank wall metal and paint m
mp
ut Standard uncertainty of thickness of tank wall m
...
NORME ISO
INTERNATIONALE 7507-2
Deuxième édition
2005-06-01
Pétrole et produits pétroliers liquides —
Jaugeage des réservoirs cylindriques
verticaux —
Partie 2:
Méthode par ligne de référence optique
Petroleum and liquid petroleum products — Calibration of vertical
cylindrical tanks —
Part 2: Optical-reference-line method
Numéro de référence
ISO 7507-2:2005(F)
©
ISO 2005
---------------------- Page: 1 ----------------------
ISO 7507-2:2005(F)
PDF – Exonération de responsabilité
Le présent fichier PDF peut contenir des polices de caractères intégrées. Conformément aux conditions de licence d'Adobe, ce fichier
peut être imprimé ou visualisé, mais ne doit pas être modifié à moins que l'ordinateur employé à cet effet ne bénéficie d'une licence
autorisant l'utilisation de ces polices et que celles-ci y soient installées. Lors du téléchargement de ce fichier, les parties concernées
acceptent de fait la responsabilité de ne pas enfreindre les conditions de licence d'Adobe. Le Secrétariat central de l'ISO décline toute
responsabilité en la matière.
Adobe est une marque déposée d'Adobe Systems Incorporated.
Les détails relatifs aux produits logiciels utilisés pour la création du présent fichier PDF sont disponibles dans la rubrique General Info
du fichier; les paramètres de création PDF ont été optimisés pour l'impression. Toutes les mesures ont été prises pour garantir
l'exploitation de ce fichier par les comités membres de l'ISO. Dans le cas peu probable où surviendrait un problème d'utilisation,
veuillez en informer le Secrétariat central à l'adresse donnée ci-dessous.
© ISO 2005
Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publication ne peut être reproduite ni utilisée sous
quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit
de l'ISO à l'adresse ci-après ou du comité membre de l'ISO dans le pays du demandeur.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax. + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Publié en Suisse
ii © ISO 2005 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 7507-2:2005(F)
Sommaire Page
Avant-propos. iv
Introduction . v
1 Domaine d'application. 1
2 Références normatives. 1
3 Termes et définitions . 1
4 Précautions. 2
5 Équipement. 2
6 Mode opératoire . 3
6.1 Principe . 3
6.2 Préparation du réservoir . 3
6.3 Circonférence de référence. 4
6.4 Lecture des décalages. 4
6.5 Jaugeage des fonds des réservoirs. 8
6.6 Autres mesurages et données. 8
7 Tolérances . 9
8 Procédure de calcul du barème de jaugeage des réservoirs. 9
8.1 Circonférence extérieure. 9
8.2 Corrections . 10
8.3 Barème de jaugeage du réservoir . 10
Annexe A (informative) Incertitudes de jaugeage des réservoirs . 11
Bibliographie . 26
© ISO 2005 – Tous droits réservés iii
---------------------- Page: 3 ----------------------
ISO 7507-2:2005(F)
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée
aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec
la Commission électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI,
Partie 2.
La tâche principale des comités techniques est d'élaborer les Normes internationales. Les projets de Normes
internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur
publication comme Normes internationales requiert l'approbation de 75 % au moins des comités membres
votants.
L'attention est appelée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable de ne
pas avoir identifié de tels droits de propriété et averti de leur existence.
L'ISO 7507-2 a été élaborée par le comité technique ISO/TC 28, Produits pétroliers et lubrifiants, sous-comité
SC 3, Mesurage statique du pétrole.
Cette deuxième édition annule et remplace la première édition (ISO 7507-2:1993), qui a fait l'objet d'une
révision technique.
L'ISO 7507 comprend les parties suivantes, présentées sous le titre général Pétrole et produits pétroliers
liquides — Jaugeage des réservoirs cylindriques verticaux:
Partie 1: Méthode par ceinturage
Partie 2: Méthode par ligne de référence optique
Partie 3: Méthode par triangulation optique
Partie 4: Méthode par mesurage électro-optique interne de la distance
Partie 5: Méthode par mesurage électro-optique externe de la distance
iv © ISO 2005 – Tous droits réservés
---------------------- Page: 4 ----------------------
ISO 7507-2:2005(F)
Introduction
La présente partie de l'ISO 7507 fait partie d'une série de Normes internationales traitant du jaugeage des
réservoirs:
ISO 4269:2001, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs par épalement — Méthode
par empotement utilisant des compteurs volumétriques
ISO 7507-1:2003, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs cylindriques verticaux —
Partie 1: Méthode par ceinturage
ISO 7507-3:1993, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs cylindriques verticaux --
Partie 3: Méthode par triangulation optique
ISO 7507-4:1995, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs cylindriques verticaux —
Partie 4: Méthode par mesurage électro-optique interne de la distance
ISO 7507-5:2000, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs cylindriques verticaux —
Partie 5: Méthode par mesurage électro-optique externe de la distance
ISO 8311:1989, Hydrocarbures légers réfrigérés — Étalonnage des réservoirs à membrane et réservoirs
pyramidaux — Mesurage physique
ISO 9091-1:1991, Hydrocarbures légers réfrigérés — Jaugeage des réservoirs sphériques à bord des
navires — Partie 1: Stéréo-photogrammétrie
ISO 9091-2:1992, Hydrocarbures légers réfrigérés — Jaugeage des réservoirs sphériques à bord des
navires — Partie 2: Méthode par triangulation
ISO 12917-1:2002, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs cylindriques
horizontaux — Partie 1: Méthodes manuelles
ISO 12917-2:2002, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs cylindriques
horizontaux — Partie 2: Méthode par mesurage électro-optique interne de la distance
La présente partie de l'ISO 7507 décrit une méthode de jaugeage des réservoirs cylindriques verticaux qui
consiste à mesurer par ceinturage une circonférence de référence, puis à déterminer les autres
circonférences à différentes hauteurs par mesurage de leurs décalages radiaux par rapport à des lignes
verticales optiques de référence. Ces circonférences sont alors corrigées pour obtenir les circonférences
intérieures vraies.
© ISO 2005 – Tous droits réservés v
---------------------- Page: 5 ----------------------
NORME INTERNATIONALE ISO 7507-2:2005(F)
Pétrole et produits pétroliers liquides — Jaugeage des
réservoirs cylindriques verticaux —
Partie 2:
Méthode par ligne de référence optique
1 Domaine d'application
La présente partie de l'ISO 7507 spécifie une méthode permettant le jaugeage des réservoirs cylindriques
pratiquement verticaux d'un diamètre supérieur à huit mètres. Elle décrit une méthode permettant la
détermination des volumes contenus dans un réservoir en fonction des hauteurs de liquide mesurées.
NOTE Les mesurages optiques (décalages) requis pour déterminer les circonférences peuvent être effectués aussi
bien à l'intérieur qu'à l'extérieur des réservoirs.
La méthode spécifiée dans la présente partie de l'ISO 7507 convient également aux réservoirs dont
l'inclinaison par rapport à la verticale n'est pas supérieure à 3 %, à condition qu'une correction soit apportée
pour tenir compte de l'inclinaison mesurée, comme décrit dans l'ISO 7507-1.
Elle est une alternative aux autres méthodes, telles que la méthode par ceinturage (ISO 7507-1) ou par
triangulation optique (ISO 7507-3).
2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent document. Pour les
références datées, seule l'édition citée s'applique. Pour les références non datées, la dernière édition du
document de référence s'applique (y compris les éventuels amendements).
ISO 4269:2001, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs par épalement — Méthode
par empotement utilisant des compteurs volumétriques
ISO 7507-1:2003, Pétrole et produits pétroliers liquides — Jaugeage des réservoirs cylindriques verticaux —
Partie 1: Méthode par ceinturage
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions donnés dans l'ISO 7507-1 ainsi que les
suivants s'appliquent.
3.1
ligne de référence optique
faisceau optique vertical (virtuel) établi au moyen du dispositif optique situé à une position donnée
3.2
chariot magnétique
dispositif mécanique pouvant être déplacé, de façon ascendante ou descendante, le long de la robe du
réservoir pour mesurer, grâce à une échelle horizontale montée sur le chariot, les décalages de la robe par
rapport à la ligne de référence optique
© ISO 2005 – Tous droits réservés 1
---------------------- Page: 6 ----------------------
ISO 7507-2:2005(F)
3.3
station
emplacement où sont placés le dispositif optique et le chariot magnétique pour effectuer des mesurages
optiques
3.4
station horizontale
station où le dispositif optique est positionné au cours de son déplacement autour de la périphérie du
réservoir
3.5
station verticale
station où le chariot magnétique est positionné le long de la paroi de la robe du réservoir
3.6
circonférence de référence
circonférence mesurée sur la virole du bas et servant de base aux calculs subséquents
3.7
décalage de référence
distance entre la paroi de la robe (à chaque station horizontale) et la ligne de référence optique mesurée au
niveau de la virole du bas, à la hauteur où la circonférence de référence est mesurée
4 Précautions
Les précautions générales et les dispositions de sécurité spécifiées dans l'ISO 7507-1 doivent s'appliquer à la
présente partie de l'ISO 7507.
5 Équipement
5.1 Équipement pour le ceinturage de réservoirs, comme spécifié dans l'ISO 7507-1:
des rubans de ceinturage;
un dynamomètre;
un cadre pour le mesurage des recouvrements;
un étau littlejohn;
un ruban de pige et un lest.
5.2 Dispositif pour le mesurage par ligne de référence optique, tel qu'un plomb optique de précision, un
niveau ou un théodolite de précision équipé d'un prisme pentagonal.
NOTE 1 Il s'agit d'instruments optiques pourvus d'un moyen de fixation sur un trépied, un support magnétique ou
d'autres moyens d'appui stables.
L'instrument, lorsqu'il est monté sur son support et calé à l'horizontale, soit manuellement à l'aide d'un niveau
à bulle, soit automatiquement s'il est équipé d'un dispositif de calage automatique, doit être capable de
donner une ligne de visée verticale.
Il convient que cet instrument ait de préférence une courte distance focale, de telle façon que lorsqu'il est
installé à sa hauteur habituelle d'utilisation, il puisse être focalisé sur l'échelle graduée au niveau de
ceinturage de référence.
2 © ISO 2005 – Tous droits réservés
---------------------- Page: 7 ----------------------
ISO 7507-2:2005(F)
Cet instrument doit avoir une résolution d'au moins 1:20 000 et être équipé d'un télescope à grossissement
d'au moins 20. L'adaptateur à prisme pentagonal utilisé avec le niveau ou le théodolite ne doit pas induire
d'erreurs significatives de collimation.
NOTE 2 On peut équiper les plombs optiques d'un système optique unique, c'est-à-dire un plomb zénithal, d'un
système optique double ou d'un système optique unique superposé donnant une ligne de visée ascendante et
descendante, c'est-à-dire un plomb nadir/zénith. Il est préférable qu'aucun de ces instruments ne comporte d'éléments
mobiles tels que des miroirs ou des prismes pentagonaux dans leur système optique afin que la stabilité de la ligne de
visée soit assurée.
5.3 Chariot magnétique, de construction robuste. Il doit être conçu pour avoir les caractéristiques
suivantes.
a) L'aimant (ou les aimants) doit (doivent) être suffisamment puissant(s) pour assurer que le chariot ne perd
pas contact avec la robe du réservoir en cas de vent violent, lorsqu'il faut franchir les soudures des
viroles ou en présence de couches épaisses de peinture ou de rouille.
b) L'aimant (ou les aimants) doit (doivent) être réglable(s) en hauteur pour permettre de modifier le jeu entre
les faces magnétiques et le réservoir, en fonction de la construction et de l'état du réservoir.
c) Un cordon ou un câble métallique doit être fixé au chariot pour pouvoir le lever ou l'abaisser depuis le toit
du réservoir ou depuis le sol à l'aide d'un système de poulies.
d) Une échelle graduée doit être fixée solidement au chariot sur son axe central. Lorsque le chariot est en
position de fonctionnement, l'échelle doit être perpendiculaire à la robe du réservoir ou horizontale.
e) L'échelle doit être fixée au chariot le plus près possible de l'axe central pour réduire les erreurs causées
par les déformations du réservoir.
NOTE On peut également utiliser des chariots non magnétiques pour garder le contact avec la robe du réservoir.
5.4 Échelle graduée, en acier et graduée en millimètres. L'échelle doit être aussi courte que possible, sa
longueur doit être déterminée par la distance à laquelle on peut installer le dispositif optique par rapport à la
robe du réservoir. L'échelle doit être étalonnée à l'aide de méthodes normalisées et de dispositifs de
référence normalisés.
6 Mode opératoire
6.1 Principe
La présente méthode de jaugeage est basée sur le mesurage précis d'une circonférence de référence au
moyen d'un ruban de ceinturage étalonné, à une seule hauteur, sur une virole accessible et ne comportant
pas d'obstacles. On effectue des mesurages réitérés, conformes aux tolérances spécifiées, afin d'éviter toute
erreur systématique dans les circonférences calculées. Les circonférences sont calculées à partir de la
circonférence de référence et des décalages mesurés aux hauteurs spécifiées et à la hauteur de la
circonférence de référence. Ces décalages donnent la mesure de l'inclinaison de la robe du réservoir. Ils se
mesurent sur un nombre déterminé de lignes de référence optiques verticales également réparties autour du
réservoir.
NOTE Voir les exemples des Figures 1 à 3.
6.2 Préparation du réservoir
Pour les réservoirs neufs et les réservoirs après réparation, remplir le réservoir au moins une fois à sa
capacité nominale de service et le laisser reposer au moins 24 h avant le jaugeage.
Si l'on jauge le réservoir alors qu'il contient du liquide, noter la hauteur de plein, la température et la masse
volumique du liquide au moment du jaugeage. Ne pas transvaser de liquide durant le jaugeage.
Dans le cas des réservoirs à toit flottant, où les mesurages de décalage peuvent être effectués à l'intérieur, le
toit flottant doit se trouver dans sa position la plus basse et reposer sur ses supports.
© ISO 2005 – Tous droits réservés 3
---------------------- Page: 8 ----------------------
ISO 7507-2:2005(F)
6.3 Circonférence de référence
La circonférence de référence a une influence directe sur le volume total du réservoir. Elle doit donc être
mesurée avec la plus grande précision possible.
Déterminer la circonférence de référence en appliquant la méthode de référence décrite dans l'ISO 7507-1 et
en tenant compte de ce qui suit.
a) Effectuer plusieurs mesurages de la circonférence de référence, soit avant le début des lectures optiques,
soit après. Si les trois premières mesures consécutives sont conformes aux tolérances spécifiées à
l'Article 7, prendre leur moyenne comme étant la circonférence de référence, et leur écart-type comme
étant l'incertitude-type. Dans le cas contraire, effectuer d'autres mesurages jusqu'à obtenir deux
écarts-types de la moyenne de toutes les mesures qui soient de la moitié des tolérances spécifiées à
l'Article 7. Adopter la moyenne arithmétique comme étant la circonférence de référence mesurée et
l'écart-type comme étant l'incertitude-type. Utiliser les procédures normalisées pour éliminer les valeurs
aberrantes manifestes.
b) Effectuer le mesurage de la circonférence de référence en un point où les conditions d'exploitation
permettent des mesurages fiables, et qui soit situé dans la plage focale de l'instrument optique. Ceinturer
le réservoir à un des niveaux suivants:
1) à 1/4 de la hauteur de la virole au-dessus de la soudure horizontale inférieure,
2) à 1/4 de la hauteur de la virole au-dessous de la soudure horizontale supérieure;
et réitérer le mesurage jusqu'à obtenir des mesures conformes aux tolérances spécifiées à l'Article 7.
6.4 Lecture des décalages
6.4.1 Installer le dispositif de ligne de référence optique (5.2), le chariot magnétique (5.3) et l'échelle
graduée (5.4) successivement sur les stations horizontales (voir 6.4.2) également espacées autour du
réservoir et le plus près possible de la robe du réservoir. Les lignes de référence doivent être choisies de
façon que le chariot ne se déplace pas sur une ligne verticale de jonction ou de soudure.
6.4.2 Le nombre minimal de stations horizontales doit être conforme au Tableau 1.
Tableau 1 — Nombre minimal de stations horizontales
Circonférence Nombre minimal de stations
m horizontales
u 50 10
> 50, u 100 12
> 100, u 150 16
> 150, u 200 20
> 200, u 250 24
> 250, u 300 30
> 300 36
NOTE 1 Afin d'éviter les erreurs systématiques, il convient que le rapport du nombre de
stations horizontales sur le nombre de tôles des segments du réservoir ne soit pas égal à un
nombre entier (par exemple 1, 2, 3, etc.).
NOTE 2 L'utilisation du nombre minimal de stations horizontales peut conduire à des
d'incertitudes supérieures à ce qui est acceptable, en particulier dans le cas de petits réservoirs.
4 © ISO 2005 – Tous droits réservés
---------------------- Page: 9 ----------------------
ISO 7507-2:2005(F)
Dimensions en millimètres
Légende
1 à 7 niveaux horizontaux 11 échelle graduée
8 ligne de référence optique 12 cordon de soudure horizontal
9 cordon de soudure vertical 13 circonférence de référence prise au plus près de la position 1
10 chariot magnétique 14 équipement optique
a) Vue en élévation du réservoir
b) Vue en plan des stations horizontales
NOTE Les stations horizontales sont notées de A à K dans la vue en plan (voir aussi 6.4.2). Dans la vue en élévation,
seules sont figurées les stations E et F.
Figure 1 — Mesurage optique des décalages par rapport à la robe du réservoir (cas typique)
© ISO 2005 – Tous droits réservés 5
---------------------- Page: 10 ----------------------
ISO 7507-2:2005(F)
a) Fibre neutre b) Cylindrique extérieur c) Cylindrique intérieur
Légende
1 ligne optique de référence
2 axe du réservoir
Circonférence extérieure de référence = C
em
Rayon extérieur de référence (virole du bas) = C /2π = R
em
Rayon extérieur de la deuxième virole = R′ , R′ ,
1 2
Épaisseur de la virole = t , t , etc.
1 2
Décalage de référence = a
Rayon de référence = R
Décalages à chaque virole = m , m , etc.
1 2
Rayon de référence intérieur = R – t = C /2π – t = R
1 em 1 1
Rayon intérieur du bas de la deuxième virole = R′
1i
Rayon intérieur du haut de la deuxième virole = R′
2i
Figure 2 — Détermination des rayons intérieurs à partir des décalages par rapport à la ligne
de référence optique extérieure
6 © ISO 2005 – Tous droits réservés
---------------------- Page: 11 ----------------------
ISO 7507-2:2005(F)
a) Fibre neutre b) Cylindrique extérieur c) Cylindrique intérieur
Légende
1 ligne optique de référence
2 axe du réservoir
Circonférence extérieure de référence = C
em
Rayon extérieur de référence (virole du bas) = C /2π = R
em
Rayon extérieur de la deuxième virole = R′ , R′ ,
1 2
Épaisseur de la virole = t , t , etc.
1 2
Décalage de référence = a
Rayon de référence = R
Décalages à chaque virole = m , m , etc.
1 2
Rayon de référence intérieur = R – t = C /2π – t = R
1 em 1 1
Rayon intérieur du bas de la deuxième virole = R′
1i
Rayon intérieur du haut de la deuxième virole = R′
2i
Figure 3 — Détermination des rayons intérieurs à partir des décalages par rapport à la ligne
de référence optique intérieure
6.4.3 Avant le début des mesurages, vérifier la verticalité de la ligne de référence optique en tournant
l'instrument optique de 180° à la première station horizontale; l'écart entre les deux valeurs mesurées aux
deux positions diamétralement opposées ne doit pas dépasser 1 sur 20 000. Vérifier également la verticalité
de la ligne de référence optique à chaque station, après achèvement des mesurages. Si la verticalité n'est
pas maintenue, réitérer la procédure de jaugeage à la station concernée.
6.4.4 À chaque station horizontale, effectuer au minimum deux mesurages de décalage par rapport à la
verticale à chaque virole, l'une à un niveau de 1/4 de la hauteur de la virole au-dessus de la soudure
horizontale inférieure et l'autre à 1/4 de la hauteur de la virole au-dessous de la soudure horizontale
supérieure. Lire l'échelle graduée au millimètre le plus proche.
6.4.5 À toutes les stations horizontales, mesurer le décalage de référence, puis mesurer progressivement
les décalages à chaque station verticale sur chaque virole à mesure que le chariot est remonté le long de la
paroi du réservoir. Après avoir mesuré la dernière valeur de décalage sur la virole supérieure, redescendre le
chariot vers la virole inférieure et mesurer à nouveau le décalage de référence. Les valeurs du décalage de
© ISO 2005 – Tous droits réservés 7
---------------------- Page: 12 ----------------------
ISO 7507-2:2005(F)
référence initiales et finales doivent concorder à deux millimètres près. Pour les calculs ultérieurs, utiliser la
moyenne arithmétique des valeurs de décalage initiales et finales.
Si les valeurs de décalage de référence ne concordent pas, réitérer les mesurages de décalage vertical à la
station horizontale concernée.
6.5 Jaugeage des fonds des réservoirs
Jauger de préférence le fond du réservoir en y versant des quantités mesurées d'un liquide non volatil (de
préférence de l'eau propre), comme indiqué dans l'ISO 4269, jusqu'à un niveau minimal qui recouvre
entièrement le fond, immergeant la plaque de touche et éliminant les effets de la déformation du fond.
Transférer des quantités mesurées supplémentaires de liquide dans le réservoir jusqu'à ce que le point le plus
élevé du fond soit recouvert et que le niveau de liquide soit supérieur au point de jaugeage par ceinturage le
plus bas (par exemple, l'emplacement du mesurage du décalage ou de la circonférence de référence, suivant
le cas). En variante, jauger le fond du réservoir par relevé géométrique à partir d'un plan de référence pour
déterminer la forme du fond du réservoir, comme spécifié dans l'ISO 7507-1.
6.6 Autres mesurages et données
6.6.1 Déterminer, au moyen d'appareils étalonnés, et traiter les données suivantes comme décrit dans
l'ISO 7507-1:
a) épaisseur de la tôle et de la couche de peinture;
b) hauteur des viroles;
c) masse volumique et température de service du liquide à stocker dans le réservoir;
d) température ambiante et température du liquide lors du mesurage;
e) hauteur maximale de remplissage;
f) corps intérieurs et extérieurs;
g) nombre, largeur et épaisseur des soudures ou des recouvrements verticaux;
h) inclinaison du réservoir déterminée à partir des écarts par rapport aux lignes verticales
i) forme, hauteur de flottaison et masse apparente dans l'air d'un toit ou d'un écran flottants.
NOTE Il est nécessaire de connaître la température moyenne et une plage de températures de la robe du réservoir
pour l'analyse des incertitudes (voir l'Annexe A).
6.6.2 Il est nécessaire de rapporter toutes les mesures de niveau au point de référence inférieur qui peut
être différent du point de repère (par exemple, un point de la cornière du fond) utilisé pour jauger le réservoir.
Déterminer toute différence de niveau entre le point de référence inférieur et le point de repère par des
méthodes de nivellement classiques ou par tout autre moyen et noter le résultat.
6.6.3 Mesurer à chaque orifice de pige, la hauteur totale témoin entre le point de référence inférieur et le
point de référence supérieur au moyen du ruban de pige et d'un lest, comme spécifié dans l'ISO 7507-1.
Noter cette hauteur totale, au millimètre près, et la marquer de manière permanente sur le réservoir à
proximité de l'orifice de pige concerné.
6.6.4 Si possible, comparer les valeurs mesurées aux dimensions correspondantes indiquées sur les plans
et vérifier les résultats présentant des écarts significatifs.
8 © ISO 2005 – Tous droits réservés
---------------------- Page: 13 ----------------------
ISO 7507-2:2005(F)
7 Tolérances
Les valeurs de circonférence de référence mesurées doivent être conformes aux tolérances données au
Tableau 2.
Tableau 2 — Tolérances absolues sur les valeurs mesurées de circonférence
Circonférence mesurée Tolérance absolue
m mm
u 25 2
> 25, u 50 3
> 50, u 100 5
> 100, u 200 6
> 200 8
8 Procédure de calcul du barème de jaugeage des réservoirs
8.1 Circonférence extérieure
Calculer la circonférence extérieure à partir des valeurs de décalage mesurées et de la circonférence de
référence en utilisant les Équations (1) à (3):
C
em
R = (1)
2π
′
R+=aR+m (2)
′
R=+Ra−m (3)
( )
où
C est la circonférence de référence, exprimée en mètres;
em
R est le rayon de la circonférence de référence, exprimé en mètres;
R′ est le rayon de la circonférence du réservoir à une hauteur de mesurage quelconque, exprimé en
mètres;
a est le décalage de référence entre la circonférence de référence et la ligne de référence, exprimé
en mètres;
m est le décalage à la même hauteur de mesurage que R′, exprimé en mètres.
Le rayon du réservoir, exprimé en mètres, à une hauteur de mesurage quelconque, basé sur l'ensemble des
stations horizontales, est donné, pour des mesurages externes, par l'Équation (4):
(am− )
∑
′′
R=+Rt− (4)
n
© ISO 2005 – Tous droits réservés 9
---------------------- Page: 14 ----------------------
ISO 7507-2:2005(F)
et pour des mesurages internes par les Équations (5) et (6):
ma−
( )
∑
RR′=−t+ (5)
n
CR′′=π2 × (6)
où
n est le nombre de stations horizontales;
t′ est l'épaisseur de la tôle et de la couche de peinture à une hauteur de mesurage quelconque,
exprimée en mètres;
t est l'épaisseur de la tôle et de la couche de peinture à la hauteur de référence, exprimée en m
...
INTERNATIONAL ISO
STANDARD 7507-2
Second edition
2005-06-01
Petroleum and liquid petroleum
products — Calibration of vertical
cylindrical tanks —
Part 2:
Optical-reference-line method
Pétrole et produits pétroliers liquides — Jaugeage des réservoirs
cylindriques verticaux —
Partie 2: Méthode par ligne de référence optique
Reference number
ISO 7507-2:2005(E)
©
ISO 2005
---------------------- Page: 1 ----------------------
ISO 7507-2:2005(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2005
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2005 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 7507-2:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Precautions .2
5 Equipment .2
6 Procedure .3
6.1 Principle.3
6.2 Preparation of the tank.3
6.3 Reference circumference.3
6.4 Offset readings.4
6.5 Tank bottom calibration .8
6.6 Other measurements and data.8
7 Tolerances .9
8 Tank capacity calculation procedure .9
8.1 Outside circumference.9
8.2 Corrections.10
8.3 Tank capacity table.10
Annex A (informative) Tank calibration uncertainties.11
Bibliography .26
© ISO 2005 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 7507-2:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7507-2 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants,
Subcommittee SC 3, Static petroleum measurement.
This second edition cancels and replaces the first edition (ISO 7507-2:1993), which has been technically
revised.
ISO 7507 consists of the following parts, under the general title Petroleum and liquid petroleum products —
Calibration of vertical cylindrical tanks:
Part 1: Strapping method
Part 2: Optical-reference-line method
Part 3: Optical-triangulation method
Part 4: Internal electro-optical distance-ranging method
Part 5: External electro-optical distance-ranging method
iv © ISO 2005 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 7507-2:2005(E)
Introduction
This part of ISO 7507 forms part of a series on tank calibration, including the following:
ISO 4269:2001, Petroleum and liquid petroleum products — Tank calibration by liquid measurement —
Incremental method using volumetric meters
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 1: Strapping method
ISO 7507-3:1993, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 3: Optical-triangulation method
ISO 7507-4:1995, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 4: Internal electro-optical distance-ranging method
ISO 7507-5:2000, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 5: External electro-optical distance-ranging method
ISO 8311:1989, Refrigerated light hydrocarbon fluids — Calibration of membrane tanks and independent
prismatic tanks in ships — Physical measurement
ISO 9091-1:1991, Refrigerated light hydrocarbon fluids — Calibration of spherical tanks in ships — Part 1:
Stereo-photogrammetry
ISO 9091-2:1992, Refrigerated light hydrocarbon fluids — Calibration of spherical tanks in ships — Part 2:
Triangulation measurement
ISO 12917-1:2002, Petroleum and liquid petroleum products — Calibration of horizontal cylindrical tanks —
Part 1: Manual methods
ISO 12917-2: 2002, Petroleum and liquid petroleum products — Calibration of horizontal cylindrical tanks —
Part 2: Internal electro-optical distance-ranging method
This part of ISO 7507 describes a method for the calibration of vertical cylindrical tanks by measurement of
one reference circumference by strapping and then determining the remaining circumferences at different
levels from measurements of radial offsets from vertical optical-reference-lines. These circumferences are
corrected to give the true internal circumferences.
© ISO 2005 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 7507-2:2005(E)
Petroleum and liquid petroleum products — Calibration of
vertical cylindrical tanks —
Part 2:
Optical-reference-line method
1 Scope
This part of ISO 7507 specifies a method for the calibration of tanks above eight metres in diameter with
cylindrical courses that are substantially vertical. It provides a method for determining the volumetric quantity
contained within a tank at gauged liquid levels.
NOTE The optical (offset) measurements required to determine the circumferences can be taken internally or
externally.
The method specified in this part of ISO 7507 is suitable for tilted tanks with up to 3 % deviation from the
vertical provided that a correction is applied for the measurement tilt, as described in ISO 7507-1.
This method is an alternative to other methods such as strapping (ISO 7507-1) and the optical-triangulation
method (ISO 7507-3).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 4269:2001, Petroleum and liquid petroleum products — Tank calibration by liquid measurement —
Incremental method using volumetric meters
ISO 7507-1:2003, Petroleum and liquid petroleum products — Calibration of vertical cylindrical tanks —
Part 1: Strapping method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7507-1 and the following apply.
3.1
optical-reference-line
vertical optical ray (virtual) that is established using the optical device at a given location
3.2
magnetic trolley
mechanical device that can be traversed up or down the tank shell wall to measure deviations in the tank shell
relative to the optical-reference-line using a horizontal scale that is mounted on the trolley
© ISO 2005 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 7507-2:2005(E)
3.3
station
location where the optical device and the magnetic trolley are placed for optical measurements
3.4
horizontal station
station where the optical device is located as it is moved around the tank circumference
3.5
vertical station
station where the magnetic trolley is located along the tank shell wall
3.6
reference circumference
circumference measured at the bottom course that forms the basis for subsequent computations
3.7
reference offset
distance of the shell wall (at each horizontal station) from the optical-reference-line measured at the bottom
course where the reference circumference is measured
4 Precautions
The general precautions and safety precautions specified in ISO 7507-1 shall apply to this part of ISO 7507.
5 Equipment
5.1 Equipment for tank strapping, as follows, as specified in ISO 7507-1:
strapping tapes;
spring balance;
step-over;
littlejohn grip;
dip-tape and dip-weight.
5.2 Optical-reference-line device, such as a precision optical plummet, a precision engineer’s level with a
pentaprism attachment, or a precision engineer’s theodolite with a pentaprism attachment.
NOTE 1 These are optical instruments with a means of attachment to either a tripod, magnetic bracket or other stable
means of support.
The instrument, when set on its support and levelled, either manually using bubble vials or automatically if an
automatic levelling device is fitted, shall be capable of giving a vertical line of sight.
The instrument should preferably be of short focal length so that, when set up at a practical working height, it
can be focused on the scale at the reference strapping level.
The instrument shall have a resolution of at least 1:20 000 and be equipped with a telescope with a
magnification of not less than 20. The pentaprism attachment for use with an engineer’s level or engineer’s
theodolite shall not introduce any significant collimation errors.
2 © ISO 2005 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 7507-2:2005(E)
NOTE 2 Optical plummets can be fitted with a single optical train, i.e. a zenith plummet, a double optical train or a
single superimposed optical train giving both upward and downward lines of sight, i.e. a nadir/zenith plummet. It is
preferable that the plummet does not have any movable elements in its optical train, such as mirrors or pentaprisms, to
ensure stability of the line of sight.
5.3 Magnetic trolley, of robust construction. Its design shall include the following features.
a) The magnet(s) shall be of sufficient power to ensure that the trolley does not lose contact with the tank
shell in conditions of high wind or when ring joints have to be negotiated or when there are heavy layers
of paint or scale.
b) The magnet(s) shall be adjustable for height so that the clearance between the magnet faces and the
tank may be varied to suit the tank construction and condition.
c) A cord or wire cable shall be attached to enable it to be raised or lowered from the tank roof or, via a
pulley system, from ground level.
d) A graduated scale shall be attached securely to the trolley at its centreline. When the trolley is in its
operational mode, the scale shall be either perpendicular to the tank shell or horizontal.
e) The scale shall be attached to the trolley as closely as possible to the centreline of an axis in order to
reduce errors caused by deformations in the tank.
NOTE Trolleys that are not magnetic can be used to maintain contact with the tank shell.
5.4 Graduated scale, made of steel and marked in millimetre increments. The length of the scale shall be
as short as is practicable and shall be determined by the distance at which the optical equipment can be set
up from the tank side. The scale shall be calibrated using standard methods and standard reference devices.
6 Procedure
6.1 Principle
This calibration method is based on the accurate measurement of a reference circumference using a
calibrated measuring tape at one level on an accessible, non-obstructed course. Repeat measurements
agreeing within specified tolerances are made to avoid any systematic error in the derived circumferences.
The derived circumferences are calculated from the reference circumference, and measurements of offsets
taken at the specified levels and at the reference circumference. These offsets are a measure of the deviation
of the tank wall. They are measured at a specified number of vertical, optical-reference-lines spaced equally
around the tank.
NOTE For examples see Figures 1 to 3.
6.2 Preparation of the tank
For new tanks or for tanks after repair, fill the tank to its normal working capacity at least once and allow it to
stand for at least 24 h prior to calibration.
If the tank is calibrated with liquid in it, record the depth, temperature and density of the liquid at the time of
calibration. Do not make transfers of liquid during the calibration.
For floating-roof tanks where offset measurements may be taken internally, the roof shall be in its lowest
position, resting on the legs.
6.3 Reference circumference
Reference circumference has a direct impact on the calibrated volume of entire tank. It, therefore, shall be
measured as accurately as possible.
© ISO 2005 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 7507-2:2005(E)
Determine the reference circumference using the reference method described in ISO 7507-1 and the following.
a) Take multiple measurements of the reference circumference either prior to the commencement or after
the completion of the optical readings. If the first three consecutive measurements agree within the
tolerances specified in Clause 7, take their mean average as the reference circumference and their
standard deviation as the standard uncertainty. If they do not agree within the tolerances specified in
Clause 7, repeat the measurements until two standard deviations of the mean of all measurements is less
than the half of the tolerances specified in Clause 7. Use the mean as the measured reference
circumference and the standard deviation as the standard uncertainty. Use standard procedures to
eliminate obvious outliers.
b) Take the measurement of the reference circumference at a position where work conditions allow reliable
measurements, and which is within the focal range of the optical instrument. Strap the tank, aiming at one
of the following levels:
1) 1/4 of the course height above the lower horizontal seam,
2) 1/4 of the course height below the upper horizontal seam;
and repeat the measurement to achieve measurements agreeing within the tolerances specified in
Clause 7.
6.4 Offset readings
6.4.1 Set up the optical-reference-line device (5.2), magnetic trolley (5.3) and graduated scale (5.4)
successively at the horizontal stations (see 6.4.2) that are equally spaced around the tank, as close as
possible to the tank wall. Reference lines shall be chosen such that the trolley does not run over a vertical
seam or its weld.
6.4.2 The minimum number of horizontal stations shall be as given in Table 1.
Table 1 — Minimum number of horizontal stations
Circumference Minimum number of horizontal stations
m
u 50 10
> 50, u 100 12
> 100, u 150 16
> 150, u 200 20
> 200, u 250 24
> 250, u 300 30
> 300 36
NOTE 1 The number of horizontal stations divided by the number of plates in tank segments
should not be equal to an integer (e.g. 1, 2, 3, etc.) in order to avoid systematic errors.
NOTE 2 Using the minimum number of horizontal stations, especially for smaller tanks, can
lead to larger-than-acceptable uncertainties.
4 © ISO 2005 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 7507-2:2005(E)
Dimensions in millimetres
Key
1 to 7 horizontal levels 11 graduated scale
8 optical-reference-line 12 weld seam (horizontal)
9 weld seam (vertical) 13 reference circumference taken close to location 1
10 magnetic trolley 14 optical equipment
a) Tank elevation
b) Plan of horizontal stations
NOTE The horizontal stations are designated A to K in the plan view (see also 6.4.2). Of these, only E and F are
shown in the elevation.
Figure 1 — Optical measurement of offsets from tank wall (typical case)
© ISO 2005 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 7507-2:2005(E)
a) Centreline flush b) Outside flush c) Inside flush
Key
1 optical-reference-line
2 tank centreline
External reference circumference = C
em
External reference radius (bottom course) = C /2π = R
em
Outer radius of second course = R′ , R′ ,
1 2
Course thicknesses = t , t , etc.
1 2
Reference offset = a
Reference radius = R
Individual course offsets = m , m , etc.
1 2
Internal reference radius = R – t = C /2π – t = R
1 em 1 1
Internal radius, second course, bottom = R′
1i
Internal radius, second course, top = R′
2i
Figure 2 — Determination of internal radius from offsets to external optical-reference-line
6 © ISO 2005 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 7507-2:2005(E)
a) Centreline flush b) Outside flush c) Inside flush
Key
1 optical-reference-line
2 tank centreline
External reference circumference = C
em
External reference radius (bottom course) = C /2π = R
em
Outer radius of second course = R′ , R′ ,
1 2
Course thicknesses = t , t , etc.
1 2
Reference offset = a
Reference radius = R
Individual course offsets = m , m , etc.
1 2
Internal reference radius = R – t = C /2π – t = R
1 em 1 1
Internal radius, second course, bottom = R′
1i
Internal radius, second course, top = R′
2i
Figure 3 — Determination of internal radius from offsets to internal optical-reference-line
6.4.3 Verify the verticality of the optical-reference-line prior to the commencement of readings by turning the
optical instrument at the first horizontal station through 180°, whereby the difference between the two readings
of the diametrically opposite positions shall be within 1 in 20 000. Also, verify the verticality of the optical-
reference-line at each station at the completion of the readings. If verticality has not been maintained, repeat
the calibration procedure at this station.
6.4.4 Take a minimum of two measurements of offsets from vertical per course at each horizontal station,
aiming at 1/4 of course height above the lower horizontal seam and at 1/4 of course height below the upper
horizontal seam. Read the graduated scale to the nearest millimetre.
6.4.5 At all horizontal stations, measure the reference offset and then take offset measurements
progressively at vertical stations on each course as the trolley is raised up the tank wall. After the last offset
measurement has been taken on the top course, lower the trolley to the bottom course and repeat the
reference offset. The initial and final reference offset readings shall agree to within two millimetres. In further
calculations, use the mean average of the initial and the final offset readings.
If agreement is not obtained, repeat vertical offset measurements at this horizontal station.
© ISO 2005 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO 7507-2:2005(E)
6.5 Tank bottom calibration
Calibrate the tank bottom, preferably by filling with measured quantities of a non-volatile liquid (preferably
clean water), as illustrated in ISO 4269, to a minimum level that covers the bottom completely, immersing the
dip-plate and eliminating the effect of bottom deformations. Transfer further measured quantities of liquid into
the tank until the highest point of the tank bottom is covered and the liquid level is higher than the lowest point
on the tank that will be calibrated by strapping (for example the offset measurement location or the reference
circumference location as appropriate). Alternatively, calibrate the tank bottom by a physical survey using a
reference plane to determine the shape of the bottom as specified in ISO 7507-1.
6.6 Other measurements and data
6.6.1 Determine, using calibrated equipment, and process the following data as described in ISO 7507-1:
a) plate and paint thickness;
b) height of the courses;
c) density and working temperature of the liquid to be stored in the tank;
d) ambient temperature and the temperature of the liquid at the time of measurement;
e) maximum filling height;
f) deadwood;
g) number, width and thickness of any vertical welds or overlaps;
h) tilt of the tank as shown by the plumb line deviations;
i) shape, landing height and apparent mass in air of any floating roof or cover.
NOTE Average mean value and a range of tank shell temperatures are required for uncertainty analysis (see
Annex A).
6.6.2 It is necessary to refer each tank dip to the dip-point, which may be in a different position from the
datum-point used for the purpose of tank calibration (e.g. a point on the bottom angle). Determine any
difference in level between the datum-point and dip-point, either by normal surveying methods or by other
means, and record it.
6.6.3 Measure the overall height of the reference point on each dip-hatch (upper reference point) above the
dip-point using the dip-tape and dip-weight as specified in ISO 7507-1. Record this overall height, to the
nearest millimetre and permanently mark it on the tank adjacent to that dip-hatch.
6.6.4 If possible, compare measurements with corresponding dimensions shown in the drawings and verify
any measurement that shows a significant discrepancy.
8 © ISO 2005 – All rights reserved
---------------------- Page: 13 ----------------------
ISO 7507-2:2005(E)
7 Tolerances
Reference circumference measurements shall agree within the absolute tolerances given in Table 2.
Table 2 — Absolute tolerances on circumferential measurements
Circumferential measurement Absolute tolerance
m mm
u 25 2
> 25, u 50 3
> 50, u 100 5
> 100, u 200 6
> 200 8
8 Tank capacity table calculation procedure
8.1 Outside circumference
Calculate the outside circumference from offset readings and the reference circumference by using
Equations (1) to (3):
C
em
R = (1)
2π
R+=aR′+m (2)
R′=+Ra−m (3)
( )
where
C is the reference circumference, expressed in metres;
em
R is the radius, expressed in metres, of the reference circumference;
R′ is the radius, expressed in metres, of the tank circumference at any measuring level;
a is the reference offset, expressed in metres, from the reference circumference to the reference line;
m is the offset, expressed in metres, at the same measuring level as R′.
The tank radius, expressed in metres, at any measuring level, based on all of the horizontal stations is given,
for external measurements, by Equation (4):
()am−
∑
R′′=+Rt− (4)
n
and for internal measurements by Equations (5) and (6):
()ma−
∑
′
RR=−t+ (5)
n
′
′
CR=π2 × (6)
© ISO 2005 – All rights reserved 9
---------------------- Page: 14 ----------------------
ISO 7507-2:2005(E)
where
n is the number of horizontal stations;
t′ is the thickness, expressed in metres, of the plate and paint at any measured level;
t is the thickness, expressed in metres, of the plate and paint at the reference level;
C ′ is the internal circumference, expressed in metres, at any measured level.
8.2 Corrections
Assuming that the capacity table has been calculated from internal radii (circumferences), corrections for the
following as described in ISO 7507-1, shall be applied to it:
a) vertical seams, if lap-welded;
b) hydrostatic-head effect;
c) expansion or contraction of the tank shell due to temperature effects;
d) tilt of the tank;
e) mass of any floating roof or cover;
f) deadwood.
8.3 Tank capacity table
Calculate and prepare the tank capacity table as described in ISO 7507-1. Calculations may be undertaken in
radii (in ISO 7507-1 the calculations are based on circumferences).
10 © ISO 2005 – All rights reserved
---------------------- Page: 15 ----------------------
ISO 7507-2:2005(E)
Annex A
(informative)
Tank calibration uncertainties
A.1 Introduction
This annex describes calculations that are used in the estimation of uncertainties of tank calibration when
using optical-reference-line method.
The calculations follow the guidelines set out in the Guide for the expression of uncertainties in measurement
[1]
(GUM) .
A.2 Symbols
The following terms and their units have been used in this annex.
Symbol Description Unit
[1]
k Coverage factor (defined in GUM) —
H Height at which calibration is performed m
j
H Height of the top measured circumference (tank height) m
max
H Height at which the reference circumference is strapped m
ref
∆h Height of the jth section m
j
h Cumulative height of the jth section m
j
uh Standard uncertainty of height (internal) of the tank for section j m
j
uL Standard uncertainty of strapping tape m
st
UL Expanded uncertainty of strapping tape length m
st
rL Resolution of strapping tape reading m
tr
uL Standard uncertainty of strapping tape reading m
tr
tL Tolerance of strapping tape tension and position m
tp
uL Standard uncertainty of strapping tape tension and position m
tp
eL Maximum error of alignment m
ta
uL Standard uncertainty of strapping tape alignment m
ta
uL Standard deviation of mean of multiple strapping measurements m
m
C Measured external reference circumference m
em
uC Standard uncertainty of measured external reference circumference m
em
uR Standard uncertainty of external (strapped) reference radius the tank m
ext
uR Standard uncertainty of internal reference radius the tank m
int
uR Standard uncertainty of any internal radius of the tank corrected for temperature m
it
uδR Standard uncertainty of radius correction for deformation due to hydrostatic head m
h
© ISO 2005 – All rights reserved 11
---------------------- Page: 16 ----------------------
ISO 7507-2:2005(E)
Symbol Description Unit
uR Standard uncertainty of any internal radius of the tank m
i
t Maximum deviation from vertical of the reference line %
v
t Maximum error of reading of the scale on the magnetic trolley m
r
Standard uncertainty of the difference of offsets measured at height H and H
ji ref
uma m
ji
respectively
wt Maximum uncertainty of thickness of the tank wall metal and paint m
mp
ut Standard uncertainty of thickness of tank wall m
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.