Submersibles -- Hydrostatic pressure test -- Pressure hull and buoyancy materials

This document specifies a test method for the hydrostatic pressure test for pressure hull and buoyancy materials of submersibles. The test sequence comprises a tightness test and the hydrostatic pressure test itself. It can also include continuous pressurization and depressurization tests, long-term static load and cycling external pressure tests. This document is applicable to the pressure structure of manned submersibles and unmanned submersibles, including the pressure hull, its accessories (such as viewports, hatches and connectors) and buoyancy materials. The long-term static load and cycling external pressure tests are only applicable to buoyancy material. This document is not applicable to submarines and other submersibles parking or operating underwater for more than one week.

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Status
Published
Publication Date
08-Aug-2019
Current Stage
6060 - International Standard published
Start Date
10-Jul-2019
Completion Date
09-Aug-2019
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ISO 21173:2019 - Submersibles -- Hydrostatic pressure test -- Pressure hull and buoyancy materials
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INTERNATIONAL ISO
STANDARD 21173
First edition
2019-08
Submersibles — Hydrostatic pressure
test — Pressure hull and buoyancy
materials
Reference number
ISO 21173:2019(E)
ISO 2019
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ISO 21173:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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
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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 2019 – All rights reserved
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ISO 21173:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

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

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

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

4 General ............................................................................................................................................................................................................................ 2

4.1 Test program ............................................................................................................................................................................................. 2

4.2 Manufacturing requirements ..................................................................................................................................................... 2

4.3 Test equipment and instruments ............................................................................................................................................ 2

4.4 Requirements for the test environment: .......................................................................................................................... 3

4.5 Test sequence ........................................................................................................................................................................................... 3

4.6 Test record .................................................................................................................................................................................................. 3

4.7 Specification .............................................................................................................................................................................................. 3

5 Detailed requirements ................................................................................................................................................................................... 3

5.1 Preparation before the tests ........................................................................................................................................................ 3

5.2 Hydrostatic pressure test ............................................................................................................................................................... 3

5.2.1 General...................................................................................................................................................................................... 3

5.2.2 Test pressurization and depressurization rates and holding time ....................................... 4

5.2.3 Hydrostatic pressure test of the pressure hull and its accessories

including viewports, hatches and connectors ........................................................................................ 4

5.2.4 Hydrostatic pressure test of buoyancy materials ................................................................................ 6

5.2.5 Qualification testing of buoyancy material ............................................................................................... 9

5.3 Optional tests ........................................................................................................................................................................................... 9

5.3.1 General...................................................................................................................................................................................... 9

5.3.2 Strain test ............................................................................................................................................................................... 9

5.3.3 Continuous pressurization and depressurization test .................................................................10

5.4 Test results processing ..................................................................................................................................................................11

5.5 Test report ................................................................................................................................................................................................11

Bibliography .............................................................................................................................................................................................................................12

© ISO 2019 – All rights reserved iii
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ISO 21173:2019(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 8, Ships and marine technology,

Subcommittee SC 13, Marine technology.

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.
iv © ISO 2019 – All rights reserved
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ISO 21173:2019(E)
Introduction

The document provides a unified specification for the hydrostatic pressure test method applicable to

the pressure hull and buoyancy materials of submersibles to confirm that their pressure resistance

performance is normal prior to assembly.
© ISO 2019 – All rights reserved v
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INTERNATIONAL STANDARD ISO 21173:2019(E)
Submersibles — Hydrostatic pressure test — Pressure hull
and buoyancy materials
1 Scope

This document specifies a test method for the hydrostatic pressure test for pressure hull and buoyancy

materials of submersibles. The test sequence comprises a tightness test and the hydrostatic pressure

test itself. It can also include continuous pressurization and depressurization tests, long-term static

load and cycling external pressure tests.

This document is applicable to the pressure structure of manned submersibles and unmanned

submersibles, including the pressure hull, its accessories (such as viewports, hatches and connectors)

and buoyancy materials. The long-term static load and cycling external pressure tests are only

applicable to buoyancy material.

This document is not applicable to submarines and other submersibles parking or operating underwater

for more than one week.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
submersible
vehicle operating underwater
3.2
manned submersible
submersible (3.1) occupied by persons
3.3
unmanned submersible
submersible (3.1) not occupied by persons
3.4
maximum working depth
maximum operating depth at which a submersible (3.1) can operate safely
Note 1 to entry: It is expressed in meters (m).
3.5
maximum working pressure

maximum pressure in which a system (pressure vessel, supporting controls and instrumentation) can

be operated
© ISO 2019 – All rights reserved 1
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ISO 21173:2019(E)
3.6
test pressure

water pressure endured by the pressure structure during the pressurization test or tightness test

Note 1 to entry: It is expressed in megapascals (MPa).
3.7
pressure hull

shell capable of withstanding the internal and/or an external pressure, in which occupants and the

required equipment are housed
3.8
viewport

penetration in the pressure vessel including a window, flange, retaining rings and seals

3.9
buoyancy material

material for a submersible (3.1), whose density is lower than that of the ambient medium

3.10
structural change

position which has a change in cross sectional area, structural configuration or other physical

characteristic
3.11
stress raiser

area where, due to the characteristics of the hull such as structural change (3.10), internal mounting,

reduced thickness due to constructional tolerances, additional loads, etc., a change in stress is likely

to occur
3.12
continuous pressurization and depressurization test

test in which the pressurization rate and depressurization rate keep the same values without any pause

for strain measurement
4 General
4.1 Test program

Prior to the test, the test program shall be prepared, including the test organization, test objective, test

equipment, inspection content, loading and unloading procedures, support conditions and test result

processing.
4.2 Manufacturing requirements

Tests shall be carried out on completion of assembly, welding of components and accessories, and

completion of heat treatment/post weld heat treatment, if applicable. The components and accessories

shall be assembled in place, provided with quality certificates for materials, manufacturing and

assembly.
4.3 Test equipment and instruments

a) The test equipment shall pass the certification, obtaining the qualifications of carrying out

hydrostatic pressure test within the validity period.

b) The test equipment and instruments shall pass the verification, which evaluates the metrological

performance of measuring instruments and determines whether they are certified or not. The

2 © ISO 2019 – All rights reserved
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ISO 21173:2019(E)

equipment and instruments shall be within the specified period of validity and be checked and

calibrated, and then remain in good condition before the test.

c) The test equipment and instruments shall be installed in the appropriate positions according to the

requirements of the test and to the relevant operating instructions, to prevent the test results from

being affected by the external environment during the test.

d) Two thirds of the range of the test pressure gauge shall not be less than the maximum test pressure.

4.4 Requirements for the test environment:

a) During the hydrostatic pressure test, the pressure medium temperature may be set as the room

temperature (10 °C to 30 °C). For viewports, the temperature of the pressurizing medium during

the test shall be the design temperature for which the viewport is rated, with a tolerance of +0/

−2,5 °C (+0/−5 °F). Brief deviations from these temperature tolerances are allowed, provided that

the deviation does not exceed 5,5 °C (10 °F) and lasts less than 10 min.
b) Atmospheric pressure: 0,084 MPa to 0,106 MPa.
c) Relative humidity: 30 % to 95 %.
d) Pressure medium: fresh water or seawater.
4.5 Test sequence

The hydrostatic pressure test of the submersible pressure structure consists of at least the following:

a) a prior tightness test;
b) the hydrostatic pressure test itself.

Optional testing includes strain measurement tests, and continuous pressurization and

depressurization tests.
4.6 Test record
All test checks shall be recorded, and relevant reports shall be filled in.
4.7 Specification

The factors and terms in this document should be used when the design is not specific. When a design

specifies other factors and terms, these should be considered, and the final decisions agreed with the

designer and the recorded for use.
5 Detailed requirements
5.1 Preparation before the tests

Prior to testing, the integrity and appearance of the pressure structure shall be checked, and parameters

such as dimensions and weights of the pressure structure shall be measured.
5.2 Hydrostatic pressure test
5.2.1 General

The test shall be carried out by steps and in two stages, namely a prior tightness test and the hydrostatic

pressure test itself. The test pressure during the hydrostatic pressure test may exceed the maximum

working pressure within a short period of time; the pressure test shall be carried out repeatedly to

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ISO 21173:2019(E)

check the consistency and stability of the test. For the selection of the test pressure, since manned

submersibles with occupants are concerned with personnel safety, the test pressure requirements

for pressure hull and buoyancy materials of manned submersibles are higher than those for pressure

hull and buoyancy materials of unmanned submersibles. For the sake of safety, the maximum test

pressure during the hydrostatic pressure test shall be higher than the maximum working pressure of

submersibles, with the specific settings and test processes as given in 5.2.2 to 5.2.4. Prior to conducting

the hydrostatic pressure test, the user shall verify that the testing object has adequate design safety

margins.
5.2.2 Test pressurization and depressurization rates and holding time

The process of the hydrostatic pressure test is to simulate the hydrostatic external pressure applied

to the pressure structure during divi
...

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