Gas cylinders — Classification of imperfections arising during the manufacture of seamless steel and aluminium alloy gas cylinders

ISO/TR 16115:2013 specifies the procedure on how to evaluate and treat the most commonly found manufacturing imperfections on seamless steel and aluminium alloy gas cylinders at visual inspection at the stage of product acceptance. It contains a template for the relevant cylinder design International Standards (i.e. ISO 9809-1, ISO 9809-2, and ISO 9809-3 for seamless steel and ISO 7866 for seamless aluminium alloy cylinders). It further contains information on how to implement the provisions into other cylinder design standards.

Bouteilles à gaz — Classification des imperfections de fabrication des bouteilles à gaz en acier et en alliage d'aluminium sans soudures

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Status
Published
Publication Date
30-Oct-2013
Current Stage
9093 - International Standard confirmed
Completion Date
27-Oct-2017
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TECHNICAL ISO/TR
REPORT 16115
First edition
2013-11-01
Gas cylinders — Classification of
imperfections arising during the
manufacture of seamless steel and
aluminium alloy gas cylinders
Bouteilles à gaz — Classification des imperfections de fabrication des
bouteilles à gaz en acier et en alliage d’aluminium sans soudures
Reference number
ISO/TR 16115:2013(E)
©
ISO 2013

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ISO/TR 16115:2013(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2013 – All rights reserved

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ISO/TR 16115:2013(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Explanatory introduction and provisions for the implementation into the cylinder
design standards . 1
Annex A (normative)  Description and evaluation of manufacturing imperfections of seamless
gas cylinders . 2
Bibliography .22
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ISO/TR 16115:2013(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 58, Gas cylinders, Subcommittee SC 3, Cylinder design.
iv © ISO 2013 – All rights reserved

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ISO/TR 16115:2013(E)

Introduction
Based on a resolution taken by ISO/TC 58/SC 3 at its 54th meeting in Sydney, a particular working
group, WG 34, was created with the following tasks:
a) consider the issue of the manufacturing defects and imperfections at the time of manufacture in
International Standards for seamless steel and aluminium alloy cylinders;
b) develop requirements that are verifiable, measurable, and practicable;
c) put forward proposals for how to include such requirements in SC 3 International Standards, no
later than the next revision of the International Standards, e.g. as an annex in the design standards
or within the main body of the text.
SC 3 asked that WG 34 take the current defect annexes of ISO 9809-1, ISO 9809-2, and ISO 9809-3 for
seamless steel and ISO 7866 for seamless aluminium alloy cylinders as a starting point.
In order to address the SC 3 resolution, it was further decided to create this Technical Report.
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TECHNICAL REPORT ISO/TR 16115:2013(E)
Gas cylinders — Classification of imperfections arising
during the manufacture of seamless steel and aluminium
alloy gas cylinders
1 Scope
This Technical Report specifies the procedure on how to evaluate and treat the most commonly found
manufacturing imperfections on seamless steel and aluminium alloy gas cylinders at visual inspection
at the stage of product acceptance.
Annex A contains a template for the relevant cylinder design International Standards (i.e. ISO 9809-1,
ISO 9809-2, and ISO 9809-3 for seamless steel and ISO 7866 for seamless aluminium alloy cylinders). It
further contains information on how to implement the provisions into other cylinder design standards.
2 Explanatory introduction and provisions for the implementation into the cyl-
inder design standards
It is intended that the provisions laid out in this Technical Report should be followed by ISO/TC 58/SC 3 working
groups dealing with the design standards for seamless steel (ISO 9809-1, ISO 9809−2, and ISO 9809−3) and
aluminium alloy gas cylinders (ISO 7866) at the next revision of these International Standards.
The tables in Annex A are based on the current “Defect Annexes” of ISO 9809-1, ISO 9809−2, and
ISO 9809−3 for seamless steel cylinders and ISO 7866 for seamless aluminium alloy cylinders. Those
imperfections applicable for the ISO 9809 series are contained in Tables A.1 and A.2, and those applicable
for ISO 7866 are contained in Tables A.3 and A.4.
They are written in such a way that they can also be incorporated in other design standards as a
normative annex.
The provisions of this Techincal Report should also serve as a basis for a future annex to each of the
other relevant design standards (other than ISO 9809-1, ISO 9809−2, ISO 9809−3, and ISO 7866) for
seamless cylinders and tubes.
If incorporated in other design standards the content of the columns “Type of imperfection”, “Description”,
and “Note” in Tables A.1, A.2, A.3, and A.4 (which were established by WG 34) should remain unchanged.
The tables should be reviewed by the other relevant ISO/TC 58/SC 3 working groups, in particular, the
column “Decision at the time of inspections and follow-up actions” and the three imperfection levels.
Where necessary, these conditions can be adapted to reflect the conditions appropriate to their product.
If the individual working groups intend to adopt other typical manufacturing imperfections specific to their
product, they can do so, provided the structure of the tables and the remaining provisions are followed.
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ISO/TR 16115:2013(E)

Annex A
(normative)

 Description and evaluation of manufacturing imperfections of
seamless gas cylinders
A.1 Introduction
Several types of imperfections can occur during the manufacture of seamless gas cylinders.
Such imperfections can be due to material defects, the manufacturing process, handling, and other
circumstances during the manufacturing process.
The aim of this Annex is to identify the manufacturing imperfections most commonly found on finished
cylinders and to provide requirements for the visual inspection at the stage of product acceptance.
NOTE 1 This Annex does not address customer specifications, e.g. cylinder aesthetics, special surface
preparations, etc.
NOTE 2 Cylinder sampling method(s) and the quantity sampled for inspection, after cylinders with imperfections
have been found, are not covered by this Annex and are prescribed in the main body of the design standard.
NOTE 3 Manufacturing imperfections can be identified and evaluated at any stage of the manufacturing process.
A.2 General
A.2.1 The visual inspection shall be conducted in good lighting on a product that is clean, dry, and
suitable enough for proper inspection of all surfaces. The visual inspection shall be conducted by eye,
and internal inspections can be augmented by a scope, dental mirror, or other suitable device. Where
magnification is used, the final assessment of the imperfection shall be evaluated as if no magnification
had been used.
In thicker parts of the cylinder, the acceptable absolute value of the size of the imperfection can be
proportionately increased to the thickness, provided that it does not adversely affect the safe performance
or integrity of the cylinder.
Where needed, the severity of a detected imperfection can be further evaluated by the use of other
devices or methods.
NOTE If unclean, the cylinder surfaces should be re-cleaned before submitting the cylinder for inspection.
A.2.2 If appropriate, small imperfections, as permitted by Tables A.1 and A.3, can be removed by local
dressing, grinding, machining, or other suitable methods. Great care shall be taken to avoid introducing
new defects or imperfections.
After such a repair, the cylinders shall be re-examined, and if the wall thickness is reduced, it shall be
rechecked and be at least at minimum guaranteed wall thickness.
A.3 Manufacturing imperfections and the procedure for their evaluation
The most commonly found safety- and performance-related manufacturing imperfections and their
descriptions are listed in Table A.1 for seamless steel cylinders and Table A.3 for seamless aluminium
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ISO/TR 16115:2013(E)

alloy cylinders. In addition, the manufacturing imperfections and their descriptions for features which
are not safety- or performance-related (cosmetic) are listed in Tables A.2 and A.4.
Limits for the repair or rejection of cylinders manufactured to this Technical Report are included in
Tables A.1 and A.3.
The acceptance or rejection conditions for gas cylinders are categorized into three levels, in
accordance with A.4.
The process that shall be followed at the final visual inspection is given in Figure A.1.
Figure A.1 — Flow-diagram for the final visual inspection of gas cylinders at the time of
product acceptance
A.4 Acceptance and rejection conditions
The following categorize the levels of imperfections and provide instructions depending on the severity
of the imperfection and regarding the disposition of the cylinders.
Level 1 imperfection
Conforming condition of a cylinder that has no adverse effects on the safe performance or integrity of
the cylinder. Cylinders with Level 1 imperfections are acceptable and do not require repair.
Level 2 imperfection
Non-conforming condition of a cylinder with features more severe than Level 1 imperfections. Cylinders
with Level 2 imperfections shall be rejected. If it is decided that a rejected cylinder with Level 2
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ISO/TR 16115:2013(E)

imperfections is to be repaired, it shall be repaired in accordance with A.2.2 and be re-inspected.
Otherwise, the cylinders are to be treated as cylinders with Level 3 imperfections.
Level 3 imperfection
Non-conforming condition of a cylinder with features more severe than Level 2 imperfections. Cylinders
with Level 3 imperfections shall be rejected. Rejected cylinders with Level 3 imperfections shall not be
repaired and shall be rendered unserviceable.
The cylinders presented to the inspector for inspection at the time of product acceptance should have
been found acceptable and should be free of imperfections to Levels 2 and 3 by the manufacturer.
A.5 Definitions
A.5.1 repair
action to return a rejected cylinder to a Level 1 condition
A.5.2 reject
cylinder that has been set aside (Level 2 or Level 3) and not allowed to go into service
A.5.3 rendered unserviceable
cylinder that has been treated in such a way as to render it impossible for use
NOTE Examples for acceptable methods to render cylinders unserviceable can be found in ISO 6406. Any
actions on cylinders rendered unserviceable are outside the scope of this Technical Report.
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ISO/TR 16115:2013(E)

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ISO/TR 16115:2013(E)

6 © ISO 2013 – All rights reserved
Table A.1 — Safety- and performance-related manufacturing imperfections and their evaluation for seamless steel cylinders
Pos Type of Description Decision at the time of inspections and follow-up actions Note
imperfec-
Level 1 imperfection Level 2 imperfection Level 3 imperfection
tion
Acceptable Reject and repair if possible Reject and render
unserviceable
(for repairs, see A.2.2)
1 S Bulge A visible swelling of the wall All cylinders with such The cause of such fail-
(see Figure A.2). imperfection. ure shall be identified.
2 S Dent (Flat) A visible depression in When the depth of the When the depth of the In all cases, the wall
the wall that has neither dent is less than 1 % of dent exceeds 1 % of thickness shall be veri-
penetrated nor removed the external-cylinder the external-cylinder fied at the imperfec-
metal and is greater in depth diameter diameter tion area and shall
than 0,5 % of the external- and or not be less than the
1) 1)
cylinder diameter (see Fig- when the diameter of when the diameter guaranteed minimum
ure A.3). (See also excessive the dent is greater than of the dent is less than wall thickness.
grinding or machining.) 30 times its depth. 30 × its depth.
1)
If the dent is not
circular, the largest
dimension shall be
taken as diameter.
3 S Dent con- A depression in the wall (see All cylinders with such
taining cut item 2 S) which contains a imperfections.
or gouge cut or gouge (See item 4 S).
(See Figure A.4.)
4 S Cut, gouge, An impression in the wall When the depth does not External surface imperfection in Internal surface imper-
groove, where metal has been exceed 5 % of the guaran- excess of Level 1. fection in excess of
metallic, removed, displaced, or teed minimum wall thick- Level 1.
They can be dressed provided
or scale redistributed with a depth ness and there are no
that the remaining wall thick- External surface
impression of greater than 3 % of the sharp notches longer than
ness below defect is greater than imperfection in excess
guaranteed minimum wall 10 times the guaranteed
the guaranteed minimum wall of Level 1 which has
thickness (see Figure A.5). minimum wall thickness.
thickness. not been repaired or
cannot be repaired.
5 S Excessive A local reduction of wall When the wall thick- When it results in the
grinding or thickness by grinding or ness is reduced to formation of a dent or
machining machining or other mechani- below the guaranteed grinding mark, treat it
cal metal removal process. minimum wall thick- as “dent” (item 2 S) or
ness. “cut” (item 3 S).

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ISO/TR 16115:2013(E)

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Table A.1 (continued)
Pos Type of Description Decision at the time of inspections and follow-up actions Note
imperfec-
Level 1 imperfection Level 2 imperfection Level 3 imperfection
tion
Acceptable Reject and repair if possible Reject and render
unserviceable
(for repairs, see A.2.2)
6 S Lamination A layering of the material External imperfection: Internal imperfection: Laminations can exist
with a surface-breaking all cylinders with such imperfec- all cylinders with such within the entire sur-
imperfection sometimes, tion. imperfection. face of the cylinder and
appearing as a discontinu- can appear as bulge or
ity, crack, lap, or bulge at the blister on the surface.
surface (see Figure A.6).
7 S Blister Not applicable for
steel.
8 S Crack A split or separation in the When removable within thick- When not removable
metal, typically appearing as ness tolerance, i.e. the remain- within the thickness
a line on the surface. ing wall thickness below defect tolerance.
is greater than the guaranteed
minimum wall thickness.
9 S Neck cracks A split or separation in the Only cylinders with tap All cylinders with neck Unlike tap marks,
and tap material, typically appear- marks. cracks. cracks can appear
marks ing as lines usually run- on the top face of the
ning down/up vertically cylinder neck.
the thread and across the
thread. (see Figure A.8).
They shall not be confused
with tap marks/thread
machining marks typically
appearing as straight line
(see Figure A.9).

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8 © ISO 2013 – All rights reserved
Table A.1 (continued)
Pos Type of Description Decision at the time of inspections and follow-up actions Note
imperfec-
Level 1 imperfection Level 2 imperfection Level 3 imperfection
tion
Acceptable Reject and repair if possible Reject and render
unserviceable
(for repairs, see A.2.2)
10 S Internal Metal flows in the shoul- Folds which are clearly Folds in excess of Level 1 which Repaired Level 2 folds
shoulder der area creating a visual visible as open depres- can be removed by a machining where the lines are
folds groove. The groove of the sions where no oxides operation until the lines of oxide still visible.
fold will always be in longi- have been trapped are no
...

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