This document specifies the requirements for periodic inspection and testing of welded steel transportable pressure drums of water capacity from 150 l up to 1 000 l and up to 300 bar test pressure intended for compressed and liquefied gases.

Gasflaschen - Wiederkehrende Inspektion und Prüfung von geschweißten Druckfässern aus Stahl - Fassungsräume bis zu 1 000 l (ISO 23088:2020)

Plinske jeklenke - Periodični pregledi in preskušanje varjenih tlačnih sodov - Prostornina do 1000 l (ISO 23088:2020)

General Information

Status
Not Published
Public Enquiry End Date
01-Oct-2020
Technical Committee
Current Stage
4020 - Public enquire (PE) (Adopted Project)
Start Date
27-Jul-2020
Due Date
14-Dec-2020
Completion Date
19-Oct-2020

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SLOVENSKI STANDARD
oSIST prEN ISO 23088:2020
01-september-2020
Plinske jeklenke - Periodični pregledi in preskušanje varjenih tlačnih sodov -
Prostornina do 1000 l (ISO 23088:2020)
Gas cylinders - Periodic inspection and testing of welded steel pressure drums -
Capacities up to 1 000 l (ISO 23088:2020)
Ta slovenski standard je istoveten z: prEN ISO 23088
ICS:
23.020.35 Plinske jeklenke Gas cylinders
oSIST prEN ISO 23088:2020 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 23088:2020
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oSIST prEN ISO 23088:2020
INTERNATIONAL ISO
STANDARD 23088
First edition
2020-02
Gas cylinders — Periodic inspection
and testing of welded steel pressure
drums — Capacities up to 1 000 l
Reference number
ISO 23088:2020(E)
ISO 2020
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Intervals between periodic inspections and tests ............................................................................................................. 2

5 List of procedures for periodic inspection and test ......................................................................................................... 2

6 Identification of pressure drum ........................................................................................................................................................... 3

7 Preparation for inspection and testing ......................................................................................................................................... 3

7.1 General ........................................................................................................................................................................................................... 3

7.2 Depressurization ................................................................................................................................................................................... 3

7.3 Devalving and flange removal .................................................................................................................................................... 3

8 External visual inspection .......................................................................................................................................................................... 3

8.1 Preparation ................................................................................................................................................................................................ 3

8.2 Procedure .................................................................................................................................................................................................... 4

9 Internal visual inspection ........................................................................................................................................................................... 4

10 Supplementary tests ......................................................................................................................................................................................... 4

11 Inspection of openings and fittings ................................................................................................................................................... 4

11.1 Internal threads ...................................................................................................................................................................................... 4

11.2 Damaged internal threads ............................................................................................................................................................. 5

11.3 Flanged openings and retaining assemblies ................................................................................................................. 5

11.4 Damaged flanged openings and/or retaining assemblies ................................................................................. 5

12 Pressure test ............................................................................................................................................................................................................. 6

12.1 General ........................................................................................................................................................................................................... 6

12.2 Proof pressure test .............................................................................................................................................................................. 6

12.3 Test procedures ...................................................................................................................................................................................... 6

12.3.1 Hydraulic test ...................................................................................................................................................................... 6

12.3.2 Pneumatic test ................................................................................................................................................................... 7

12.4 Acceptance criteria .............................................................................................................................................................................. 7

13 Repair of pressure drums ........................................................................................................................................................................... 8

13.1 Welds ............................................................................................................................................................................................................... 8

13.2 Other repairs ............................................................................................................................................................................................. 8

13.3 Requirements for repair ................................................................................................................................................................. 8

14 Inspection of valves ........................................................................................................................................................................................... 8

15 Final operations .................................................................................................................................................................................................... 8

15.1 Drying and cleaning ............................................................................................................................................................................ 8

15.2 Painting .......................................................................................................................................................................................................... 9

15.3 Fitting valves ............................................................................................................................................................................................. 9

15.4 Fitting of flanges .................................................................................................................................................................................... 9

15.5 Verification of tare................................................................................................................................................................................ 9

15.6 Retest marking ........................................................................................................................................................................................ 9

15.7 Reference to the next test date ...............................................................................................................................................10

15.8 Records .......................................................................................................................................................................................................10

16 Rejection and rendering unserviceable ....................................................................................................................................10

Annex A (informative) Periodic inspection and test periods ...................................................................................................12

© ISO 2020 – All rights reserved iii
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)

Annex B (normative) Description, evaluation of defects and conditions for rejection of

pressure drums at the time of visual inspection..............................................................................................................13

Bibliography .............................................................................................................................................................................................................................19

iv © ISO 2020 – All rights reserved
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oSIST prEN ISO 23088:2020
ISO 23088:2020(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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 4,

Operational requirements for gas cylinders.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2020 – All rights reserved v
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)
Introduction

This document provides information and procedures for the periodic inspection and testing of

pressure drums and the condition of the test equipment. It addresses requirements that reflect current

practice and experience. The principal aim of a periodic inspection and testing procedure is that at the

satisfactory completion of the inspection the pressure drums can be reintroduced into service for a

further period of time.
[7]

This document has been written so that it is suitable to be referenced in the UN Model Regulations .

vi © ISO 2020 – All rights reserved
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oSIST prEN ISO 23088:2020
INTERNATIONAL STANDARD ISO 23088:2020(E)
Gas cylinders — Periodic inspection and testing of welded
steel pressure drums — Capacities up to 1 000 l

CAUTION — Some of the tests specified in this document involve the use of processes that could

lead to a hazardous situation.
1 Scope

This document specifies the requirements for periodic inspection and testing of welded steel

transportable pressure drums of water capacity from 150 l up to 1 000 l and up to 300 bar test pressure

intended for compressed and liquefied gases.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 10286, Gas cylinders — Terminology

ISO 11114-1, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 1:

Metallic materials

ISO 11114-2, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 2:

Non-metallic materials
ISO 13341, Gas cylinders — Fitting of valves to gas cylinders
ISO 13769, Gas cylinders — Stamp marking

ISO 21172-1, Gas cylinders — Welded steel pressure drums up to 3 000 litres capacity for the transport of

gases — Design and construction — Part 1: Capacities up to 1 000 litres

ISO 22434, Transportable gas cylinders — Inspection and maintenance of cylinder valves

ISO 25760, Gas cylinders — Operational procedures for the safe removal of valves from gas cylinders

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 10286 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
pressure drum

welded transportable pressure receptacle of a water capacity exceeding 150 l and of not more than 1 000 l

EXAMPLE Cylindrical receptacles equipped with rolling hoops, spheres on skids.
[SOURCE: UN Model Regulations, as amended]
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)
3.2
rejected pressure drum
pressure drum (3.1) not fit for service without further evaluation
3.3
minimum design wall thickness

thickness of the pressure drum (3.1) wall calculated from the design standard, taking into account the

material properties and dimensions at time of manufacture

[SOURCE: ISO 18119:2018, 3.4, modified — "cylinder" replaced by "pressure drum".]

4 Intervals between periodic inspections and tests

A pressure drum shall be due for periodic inspection and testing on its first receipt by a filler following

the expiry of the established interval or, in the absence of regulations, in accordance with the UN Model

Regulations (see Annex A). The expiry date is based on the last test date shown on the pressure drum.

Provided the pressure drum has not been subjected to abusive and abnormal conditions such as being

involved in an accident, heat exposure or other severe conditions that would render the pressure drum

unsafe, there is no requirement for the user to return a pressure drum before the contents have been

used even though the periodic inspection and test interval has lapsed. However, pressure drums,

particularly those containing corrosive gases, should be retested within a period not exceeding twice

the periodic inspection and test interval of the applicable regulations.
5 List of procedures for periodic inspection and test

Each pressure drum shall be submitted to a periodic inspection and test. The following procedures

form the requirements for such inspection and testing, and are explained more fully in later clauses:

a) identification of pressure drum (see Clause 6);
b) preparation for inspection and testing (see Clause 7);
c) depressurization (see 7.2);
d) devalving and flange removal (see 7.3);
e) external visual inspection (see Clause 8);
f) internal visual inspection (see Clause 9);
g) supplementary tests (see Clause 10);
h) inspection of openings and fittings (see Clause 11);
i) pressure test (see Clause 12);
j) repair of pressure drums (see Clause 13);
k) inspection of valves (see Clause 14);
l) final operations (see Clause 15);
m) rejection and rendering unserviceable (see Clause 16).

These procedures should be performed in the sequence listed in order to improve the safety of the

operation and to detect potential harmful damage.

When a pressure drum passes the above listed procedures, but the condition of the pressure drum

remains in doubt, additional, supplementary tests shall be performed to confirm its suitability for

continued service or the pressure drum shall be rejected (see Clause 16).
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)

Pressure drums that fail an inspection or test shall be rejected (see Clause 16).

Depending on the reason for rejection, some pressure drums may be returned to service after further

evaluation. The requirements for returning a rejected pressure drum to service are provided in

Clause 16 and Annex B.

The eyesight acuity of operators is critical and should be checked by an optician on a yearly basis.

6 Identification of pressure drum

The labelling and permanent marks on the pressure drum shall be checked and the information

recorded before carrying out any further work. Pressure drums with incorrect or illegible marks shall

be set aside for further evaluation.

Pressure drums with contents that are unknown shall also be set aside for further evaluation.

7 Preparation for inspection and testing
7.1 General

Pressure drums shall be made safe before carrying out any further inspections. This can include

purging or other operations depending upon the gas service involved. Pressure drums that cannot be

safely emptied of product shall be set aside for further evaluation.

Particular attention shall be paid to pressure drums that have contained flammable, oxidizing or toxic

gases to eliminate risks during the internal visual inspection. Additionally, as some liquefied products

cannot be removed from the pressure drum by only venting, an additional check such as weighing the

pressure drum and comparing this value to its tare may be required.
7.2 Depressurization

Before removing the valve, a check shall be performed to ensure that the pressure drum does not

contain any gas under pressure.

A check shall be performed to establish that the valve is not obstructed or inoperable in accordance

with ISO 25760.
7.3 Devalving and flange removal

WARNING — The uncontrolled opening of the valve and/or the removal of the valve and flange

from a pressure drum can lead to injury, death and/or property damage.

The valve may be removed only after the pressure drum has been depressurized and it has been

established that there is no obstruction to gas flow in the pressure drum's valve. Devalving shall be

performed in accordance with ISO 25760.

The flange(s) shall only be removed after the pressure drum has been devalved in accordance with

ISO 25760.
8 External visual inspection
8.1 Preparation

Each pressure drum shall be cleaned and have all labels, loose coatings, corrosion products, tar, oil or

other foreign matter removed from its external surface, e.g. by brushing, shot blasting (under controlled

conditions), water jet abrasive cleaning, chemical cleaning or other methods. Care shall be taken to

ensure that the integrity of the pressure drum is not compromised by the cleaning process.

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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)
8.2 Procedure

The external surface of each pressure drum shall undergo a thorough visual inspection for:

— dents, cuts, gouges, bulges, cracks, laminations or excessive wear;
— heat damage, torch or electric arc burns (as identified in Table B.1);

— corrosion (as defined in Table B.2) — attention shall be given to areas where water can be trapped;

— defects to welds, welded attachments and the areas adjacent to them;

— other defects such as illegible or unauthorized stamp marks, unauthorized additions or modifications;

— integrity of all permanent attachments, e.g. shrouds, lifting points, lifting pockets; and

— damage to rolling bands.
If the results of the external visual inspection are in doubt, see Clause 10.

For rejection criteria, see Annex B. Pressure drums no longer suitable for continued service shall be

rendered unserviceable as defined in Clause 16.
9 Internal visual inspection

Once the requirements of Clause 7 have been met, each pressure drum shall be inspected internally to

identify defects such as those listed in 8.2. Flange(s), if present, shall be removed in accordance with 7.3

to facilitate the internal inspection of the pressure drum.

Precautions shall be taken to ensure that the method of illumination used for the internal visual

inspection presents no hazard to the person carrying out the inspection. Any internal lining or coating

that can prevent a thorough examination shall be removed.

Any pressure drum showing the presence of foreign matter or signs of corrosion shall be cleaned under

closely controlled conditions by a method such as shot blasting, water jet abrasive cleaning, flailing,

steam jet, hot water jet, chemical cleaning or other approved method. Care shall be taken to avoid

damage to the pressure drum. The pressure drum shall be re-inspected after the cleaning process.

10 Supplementary tests

Where there is doubt concerning the type and severity of a defect found on visual inspection (see

Clauses 8 and 9), or when the cleaning processes might have reduced the wall thickness, additional

tests or methods of examination may be performed. These additional tests or methods of examination

include ultrasonic examination (UT), checking the weight of the pressure drum or other non-destructive

testing such as x-ray or dye-penetrant to investigate the presence of surface imperfections.

Only when doubt is eliminated may the drum be further processed (see Annex B).
11 Inspection of openings and fittings
11.1 Internal threads
The internal threaded openings shall be visually examined to ensure they are:
— clean and of full form;
— free of damage;
— free of burrs;
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)
— free of cracks; and
— free of other imperfections.

Where there is any doubt as to the condition of the threaded openings and the threads of the fittings of

pressure drums, the threads shall be checked using a thread gauge.

Threaded openings and the threads of the fittings of pressure drums used in toxic, flammable or

corrosive service shall be examined using an appropriate thread gauge or gauges.

For examples on the use of thread gauges, see ISO 11363-2. In all cases, the threads shall be checked by

a person trained in gauging threads.
11.2 Damaged internal threads

When necessary, threads may be re-tapped to clean and rectify the appropriate number of

effective threads. After re-tapping, the threads shall be checked using the applicable thread gauge

(e.g. ISO 11363-2).
11.3 Flanged openings and retaining assemblies

If the pressure drum is fitted with flanged openings, they shall be inspected to ensure that they are:

— clean faced;
— free of damage to the mating surfaces; and
— free of cuts or gouges.
For retaining assemblies, including bolts/studs, ensure that:
— the profile conforms to the required specification;
— is free from all surface defects; and

— the materials are compatible with the intended gas service, even those that are not in the gas stream

(see ISO 11114-1).
11.4 Damaged flanged openings and/or retaining assemblies

If the design permits, damaged flange faces on both the pressure drum and the flange may be re-

machined to enable a pressure seal to be made on re-assembly.

When retaining assemblies have been replaced, ensure that they are compatible with the intended gas

service (see ISO 11114-1 or ISO 11114-2, as applicable).
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oSIST prEN ISO 23088:2020
ISO 23088:2020(E)
12 Pressure test
12.1 General
Each pressure drum shall be subjected to a proof pressure test (see 12.2).
12.2 Proof pressure test

WARNING — Appropriate measures shall be taken to ensure safe operation and to contain any

energy that might be released. It should be noted that pneumatic proof pressure tests require

more precautions than hydraulic proof pressure tests, regardless of the size of the pressure

drum. Any error in carrying out this test is highly likely to lead to a rupture under gas pressure.

Therefore, these tests shall be carried out only after ensuring that the safety measures adopted

satisfy the safety requirements.

The hydraulic proof pressure test shall use a fluid, usually water, as the test medium. The test procedure

shall be performed in accordance with 12.3 as appropriate to the design of the pressure drum. The test

pressure shall be in accordance with the stamp mark of the pressure drum.

A pneumatic pressure test may be substituted for the hydraulic proof pressure test provided that a risk

assessment has been carried out. Personnel using pneumatic testing need to ensure that precautions

are taken to contain any energy released if a pressure drum fails. The energy required to conduct a

pneumatic pressure test is considerably more than that required for a hydraulic pressure test and can

cause extensive damage in the event of failure if adequate precautions have not been taken.

When using air as the medium for the pneumatic pressure test, care shall be taken due to the oxidizing

potential of high pressure air. At 300 bar, the partial pressure of oxygen is approximately 60 bar.

Pressure drums that have internal flammable materials (e.g. coatings containing hydrocarbons) shall

not undergo a pneumatic pressure test that uses high pressure air.

Care shall be taken during the periodic inspection and testing of pressure drums that have been used in

flammable gas service.
12.3 Test procedures
12.3.1 Hydraulic test
12.3.1.1 General

The pressure in the pressure drum shall be increased gradually until the test pressure is reached. The

pressure shall be held for a minimum of 10 min with the pressure drum isolated from the pressure

source. During the test period, there shall be no decrease in the recorded pressure or evidence of any

leakage. Safety precautions shall be taken, even for a hydraulic test, due to the considerable stored

energy in a pressure drum.
12.3.1.2 Test equipment

12.3.1.2.1 All rigid pipe work, flexible tubing, valves, fittings and components forming the pressure

system of the test equipment shall be designed to withstand a pressure 1,5 times the maximum test

pressure of the pressure drum that is to be tested. Flexible tubing shall have sufficient wall thickness to

prevent kinking.
...

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