ISO 23648:2026

• Abstract:

  This document specifies a test method for assessing the fire performance of water-filled plastic pipes and fibre reinforced plastic (FRP) pipes.

• Status: Published
• Publication Date: 30-Sep-2026
• ICS: 13.220.40 - Ignitability and burning behaviour of materials and products
• ICS: 23.040.20 - Plastics pipes
• Technical Committee: ISO/TC 61/SC 4 - Burning behaviour
• Drafting Committee: ISO/TC 61/SC 4 - Burning behaviour
• Current Stage: 6060 - International Standard published
• Start Date: 01-Oct-2026
• Due Date: 28-Nov-2026
• Completion Date: 01-Oct-2026

ISO 23648:2026 is an International Standard from ISO for an impinging flame test on water-filled plastic pipes. It specifies a test method for assessing the fire performance of water-filled plastic pipes and fibre reinforced plastic (FRP) pipes. In practice, it gives laboratories and suppliers a repeatable way to check whether a pipe can stay sealed when exposed to flame while holding water pressure.

What does ISO 23648:2026 specify?

ISO 23648:2026 specifies a fire test method for water-filled plastic pipes and FRP pipes, with an emphasis on ship-related piping applications. The document is organized to take the user from the test principle through apparatus, specimen preparation, test procedure, pass/fail criteria and reporting.

Annex	What it covers
Annex A	Informative examples of the test view and of measuring water temperature and pressure during the test

The main clauses cover scope, normative references, terms and definitions, principle, apparatus, test specimen, conditioning, test method, acceptance criteria, test report and precision.

What are the key requirements of ISO 23648:2026?

ISO 23648:2026 sets out a combined flame-and-pressure test. The pipe specimen is filled with water, exposed to specified burners for 30 minutes, and then held under pressure for another 15 minutes after the flame exposure.

• Clause 4, Principle - The specimen must be water-filled and kept under specified pressure while flames impinge on it. This matters because the test is aimed at the pipe's ability to retain water in a fire situation, not just its surface burning behavior.

• Clause 5.1 and 5.2, burners and fuel - The test uses a torch burner arrangement with defined burner dimensions, propane of at least 95% purity, and controlled gas flow. For pipes up to 150 mm nominal diameter, the burner set uses two rows; larger pipes need additional rows to maintain the specified heat flux. This matters because the heat input must be controlled if results are to be comparable.

• Clause 5.3 to 5.8, apparatus - The setup includes steel specimen supports, a water supply system that maintains 0.3 MPa ± 0.05 MPa, a timing device, a heat flux meter calibrated to ISO 14934-3, a sheathed thermocouple for water temperature, and end-closure devices resistant to 150 °C. This means the lab needs equipment that can hold pressure, measure heat and temperature, and withstand the test environment.

• Clause 6 and 7, specimen preparation - The specimen must be at least 1.5 m long, mounted horizontally, and free of trapped air. Joints and insulation are included when they are part of the intended product, and the specimen is conditioned at 23 °C ± 5 °C and 50% ± 10% relative humidity for at least 24 hours, or until equilibrium. In practice, the test should represent the product as it will actually be used.

• Clause 8, test method - The test room must have adequate air supply and an atmospheric temperature between 15 °C and 35 °C. The water inside the specimen starts at not less than 15 °C, and the test records deformation, leakage, water temperature and water pressure. If pressure cannot be maintained above 0.25 MPa because of leakage, the test is stopped.

• Clause 9 and 10, acceptance and reporting - The specimen passes if it shows no leakage during fire exposure, except for slight weeping up to 0.2 l/min through the wall, and if pressure is maintained during the fire and post-fire pressure-hold period. The report records the laboratory, sponsor, manufacturer or supplier, specimen construction, insulation details if used, test conditions, pass/fail decision and any reason for invalidity. This is what makes the result traceable for quality control or product qualification.

What terms does ISO 23648:2026 define?

ISO 23648:2026 uses the fire-safety vocabulary of ISO 13943 for its terms and definitions. The following terms are especially important in the test method:

• Fibre reinforced plastic (FRP) - A plastic pipe reinforced with fibres, tested here alongside plastic pipes.
• Stagnant water - Water held in the specimen during the test rather than flowing through it.
• Heat flux meter - The instrument used to check the heat load at the specimen position.
• Acceptance criteria - The pass/fail conditions in Clause 9, based on leakage and pressure retention.
• Test specimen - The pipe section being tested, including a joint or insulation when those features are part of the evaluation.
• Boiling liquid expanding vapor explosion (BLEVE) - The rapid pressure-related failure warned against if the water pressure drops suddenly.

Who uses ISO 23648:2026?

ISO 23648:2026 is used by testing laboratories, pipe manufacturers, suppliers and test sponsors. It is also relevant to engineers and quality managers working with plastic pipes or FRP pipes for ships.

The introduction points to shipboard services such as fresh water, sanitary and drain piping, sea-water piping and liquid cargo piping. That makes the document useful when a buyer or designer needs evidence that a pipe system can withstand fire exposure while remaining watertight.

Which standards are used with ISO 23648:2026?

ISO 23648:2026 cites ISO 13943 for the fire-safety vocabulary used throughout the document. It cites ISO 14934-3 for calibration and use of the heat flux meter.

The introduction also says the method was developed from the International Maritime Organization (IMO) guidelines in IMO Assembly resolution A.753(18) as amended. That background explains why the test is written for ship applications.

What does the ISO 23648:2026 document contain?

ISO 23648:2026 contains the full test sequence, the required apparatus and the reporting items needed for a repeatable fire-performance assessment. Figures show the burner appearance, the burner arrangement and an example test setup.

Annex A gives example views of the test and example records of water temperature during testing. The document also includes the specimen preparation details, the water-pressure and heat-flux checks, the stop condition for leakage, and the post-fire pressure-hold step used to judge performance.

International
Standard
ISO 23648
First edition
Plastics — Impinging flame test on
2026-10
water-filled plastic pipes
Plastiques — Essai de flamme incidente sur des canalisations
plastiques remplies d'eau
Reference number
ISO 23648:2026(en)
© ISO 2026
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 23648:2026(en)
Contents  Page
Foreword .iv
Introduction .v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Principle . 1
5  Apparatus . 1
5.1 Heat source .1
5.2 Fuel gas supply system .2
5.3 Test specimen support . .3
5.4 Water supplying system .3
5.5 Timing device .3
5.6 Heat flux meter .3
5.7 Thermocouple .3
5.8 Closing devices of specimen .4
6  Test specimen . 4
6.1 Dimensions .4
6.2 Joints .4
6.3 Insulation .4
7  Conditioning of specimen . 4
8  Test method . 4
8.1 Test conditions .4
8.2 Heat flux measurement .4
8.3 Preparation .4
8.4 Test procedure .5
9  Acceptance criteria . 5
10  Test report . 5
11  Precision of the test . 6
Annex A (informative)  Examples of view of the test, measurement of water temperature and
pressure during the test . 7
Bibliography . 9

iii
ISO 23648:2026(en)
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
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 4, Burning
behaviour.
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 23648:2026(en)
Introduction
Plastic pipes and fibre reinforced plastics pipes (FRP pipes) exhibit corrosion resistance against water,
including sea water and liquid chemicals. These pipes have been used on ships in various applications, such
as piping for supplying fresh water, sanitary and drain piping, sea-water piping and liquid cargo piping.
The International Maritime Organization (IMO) adopted guidelines on use of plastic pipes (IMO Assembly
[1]
resolution A.753(18) as amended ). These guidelines contain requirements on the fire performance of
plastic pipes and of FRP pipes to be used on-board ships. These guidelines also contain a brief explanation
of the test procedures on a fire performance test for liquid-filled plastic pipes in the Appendix 2 of IMO
A.753(18). However, the description of the fire test in the current guideline is very short and insufficient to
conduct the test in a uniform and consistent manner.
[1]
This document was developed based on the IMO A.753(18) and provides detailed descriptions of the fire
test methods applicable to plastic pipes and FRP pipes used on ships.

v
International Standard ISO 23648:2026(en)
Plastics — Impinging flame test on water-filled plastic pipes
1  Scope
This document specifies a test method for assessing the fire performance of water-filled plastic pipes and
fibre reinforced plastic (FRP) pipes.
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 13943, Fire safety — Vocabulary
ISO 14934-3, Fire t
...