ISO 22548:2021

Ships and marine technology - Performance test procedures for LNG fuel gas supply systems (FGSS) for ships

This document specifies evaluation methods of characteristics such as pressure, flow rate, temperature and system stability of fuel gas supply systems (FGSS), which are manufactured to use vaporized liquefied natural gas (LNG) or boil-off gas as fuel gas supply to the vessel's gas consumers. It is applicable to evaluate the performance of the LNG FGSS: (1) prior to delivery or after installation on board a ship, and (2) to assure the system characteristics are taken into account for the entire gas consumers during ship’s gas trial or sea trial.

Navires et technologie maritime — Procédures d'essais de performance des systèmes d'alimentation en gaz combustible GNL (FGSS) pour navires

General Information

• Status: Published
• Publication Date: 01-Jun-2021
• ICS: 47.020.99 - Other standards related to shipbuilding and marine structures
• Technical Committee: ISO/TC 8 - Ships and marine technology
• Drafting Committee: ISO/TC 8/WG 8 - Liquid and gas fueled vessels
• Current Stage: 6060 - International Standard published
• Start Date: 02-Jun-2021
• Due Date: 04-May-2021
• Completion Date: 02-Jun-2021

Overview

ISO 22548:2021 - "Ships and marine technology - Performance test procedures for LNG fuel gas supply systems (FGSS) for ships" defines standardized methods to evaluate the key operational characteristics of shipboard LNG fuel gas supply systems. The standard covers measurement and verification of pressure, flow rate, temperature and system stability for FGSS that deliver vaporized LNG or boil‑off gas to shipboard gas consumers. It applies to testing prior to delivery or after installation on board, and to support whole‑ship gas trials or sea trials.

Key topics and technical requirements

• Test parameters: Record pressure, flow rate and temperature (and ambient conditions) at a frequency of no less than once every 5 s. Instruments must be calibrated.
• Test fluid: LNG is the primary medium. Substitutes (e.g., liquefied nitrogen) can be used if colder and compatible, with correction factors (referenced to ISO 6976 or equivalent).
• Test arrangement & safety: Ensure cryogenic conditions, replace air with inert gas as required, minimize methane emissions, and verify safety systems before testing.
• Safety tests: Verify alarm/safety devices, control system integration, and cryogenic mechanical/electrical functions at design or lower temperatures before pressurization.
• ESD and blow down: Confirm emergency shutdown operation and safe depressurization capability; piping shall be nitrogen‑pressurized before the ESD/blow‑down check.
• Performance test procedure: Stepwise load sequence - ramp through 25%, 50%, 75%, 100% of test flow rate (and back down), maintaining each step for 30 minutes while recording data. Assess maximum/minimum pressures, pressure pulsation, mean flow rate and average temperatures.
• Additional tests: Unit production tests (including hydrostatic/pneumatic pressure test), type tests and endurance tests are included as further verification options.
• Reporting: Produce a formal test report (examples in Annex A) documenting test setup, parameters, data logs and results.

Applications and users

ISO 22548 is used to:

• Validate FGSS performance before delivery or after installation on LNG‑fuelled vessels
• Support ship gas trials and sea trials to ensure fuel supply characteristics meet engine and ship system requirements Key stakeholders:
• Shipowners and operators
• FGSS manufacturers and suppliers
• Shipyards and integrators
• Classification societies and regulators
• Engine makers and test laboratories

Related standards

• IMO IGF Code and IGC Code (design and safety requirements for gas‑fuelled ships)
• ISO 6976 (for gas properties / correction factors when alternative test media are used)
• Relevant classification society rules and national administration requirements

Keywords: ISO 22548:2021, LNG FGSS testing, fuel gas supply system, performance test procedures, ship gas trial, ESD test, cryogenic function test, LNG flow rate testing.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 22548
First edition
2021-06
Ships and marine technology —
Performance test procedures for LNG
fuel gas supply systems (FGSS) for
ships
Navires et technologie maritime — Procédures d'essais de
performance des systèmes d'alimentation en gaz combustible GNL
(FGSS) pour navires
Reference number
©
ISO 2021
© ISO 2021
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
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Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test arrangement . 2
4.1 Test preparation . 2
4.2 Test fluid . 3
4.3 Test parameters . 3
5 Test procedure . 4
5.1 Safety test . 4
5.1.1 Test of e.g. alarm and safety devices . 4
5.1.2 Cryogenic function tests . 4
5.1.3 ESD and blow down test . . 4
5.2 Performance test . 4
6 Additional tests . 5
6.1 Unit production test. 5
6.2 Type test . 6
6.3 Endurance test . 6
7 Test report . 6
Annex A (informative) LNG fuel gas supply systems (FGSS) test report — Example .7
Annex B (informative) Typical examples of LNG FGSS within the scope of the test .9
Bibliography .12
Foreword
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 8, Ships and 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 2021 – All rights reserved

Introduction
In response to an increased number of ships using LNG fuel, the International Maritime Organization
(IMO) adopted the IGF code that specifies mandatory requirements of the LNG fuel tank, LNG fuel engine,
fuel gas supply system (FGSS), bunkering, control of safety system, monitoring, and fire extinguishing
systems, etc. to ensure the safety of gas-fuelled ships.
The requirements of the IGF and IGC Codes apply to the design and manufacture of LNG FGSS. However,
no widely recognized standards in terms of the performance testing of FGSS has yet been established;
thus, FGSS is tested according to a case-by-case agreement between the buyer and the supplier. For this
reason, there have been needs to develop a standard for performance test methods of FGSS commonly
acceptable to all stakeholders (e.g. shipowners, classification societies, engine makers, shipyards, etc.).
In this context, this document sets up a performance test procedure for the LNG FGSS, which consists
of equipment such as pumps, heat exchangers, valves, piping, etc. With this document, it is expected
that i) the performance of LNG FGSS be identified from an objective point of view, ii) useful information
be provided to all stakeholders, and iii) development of more reliable LNG FGSS be facilitated, thus
contributing to the growth of relevant industries and benefiting all stakeholders.
In addition, as specific requirements from classification societies and/or administrations can apply to
the LNG FGSS concerned, the buyer is expected to identify those before placing a purchase order. The
supplier and the buyer are further expected to agree on any additional applicable requirements.
INTERNATIONAL STANDARD ISO 22548:2021(E)
Ships and marine technology — Performance test
procedures for LNG fuel gas supply systems (FGSS) for
ships
1 Scope
This document specifies evaluation methods of characteristics such as pressure, flow rate, temperature
and system stability of fuel gas supply systems (FGSS), which are manufactured to use vaporized
liquefied natural gas (LNG) or boil-off gas as fuel gas supply to the vessel's gas consumers. It is applicable
to evaluate the performance of the LNG FGSS: (1) prior to delivery or after installation on board a ship,
and (2) to assure the system characteristics are taken into account for the entire gas consumers during
ship’s gas trial or sea trial.
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.
IMO, International Code for the Construction and Equipment of Ships carrying Liquefied Gases in Bulk (IGC
Code)
IMO, International Code of Safety for Ships using Gases or other Low-flashpoint Fuels (IGF Code)
3 Terms and definitions
For the purpose 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
LNG fuel gas supply system
LNG FGSS
system that supplies gas fuel at the temperature, pressure and flow conditions required by the gas
consumer, from the fuel tank(s) to the gas consumer, excluding the fuel tank(s), in-tank pump(s), tank
ESD valve(s) and the master gas fuel valve(s) used to control the gas supply
3.2
maximum pressure
maximum operating pressure (MPa) measured during the test period
3.3
minimum pressure
minimum operating pressure (MPa) measured during the test period
3.4
pressure pulsation
pressure variation (MPa) during the test period, defined as the difference between the maximum
pressure (3.2) and the minimum pressure (3.3)
3.5
flow rate
arithmetic mean of the mass flow rate (kg/h) measured during the test period
3.6
average temperature
arithmetic mean of the temperature (°C) measured during the test period
3.7
test temperature
temperature (°C) of the fluid during the test, designated by the client
3.8
test pressure
pressure (MPa) of the fluid during the test, des
...