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.