LNG bunkering — fueling ships with liquefied natural gas — has grown from a niche to standard practice in major ports, and small-scale LNG distribution is following the same curve. The valve requirements sit at the intersection of cryogenic engineering and marine safety rules.
Where Valves Sit in a Bunkering Chain
Shore tank → transfer pumps → bunkering manifold → hose/arm with breakaway coupling → ship manifold → vessel tanks. Each interface needs isolation, check and emergency shutdown (ESD) functions rated for −162 °C service.
The Non-Negotiables
- BS 6364 / ISO 28921 cryogenic type testing with extended bonnets — the baseline for every valve touching LNG. Details in our cryogenic buyer’s guide.
- Fire-safe design (API 607 / ISO 10497) — LNG is a Group 1 fluid; a fire must not turn a valve into a leak path. See fire-safe ball valves.
- ESD compatibility: pneumatic spring-return or electric fail-safe actuation with defined stroke times — our actuation packages cover both.
- Marine class rules: IGF Code for the ship side, IACS class approvals, and ISO 20519 for the bunkering interface itself.
Typical Valve Selection
| Location | Typical choice |
|---|---|
| Tank isolation | Cryogenic triple-offset butterfly or top-entry ball |
| Manifold isolation | Cryogenic ball, extended bonnet, fire-safe |
| ESD | Actuated cryogenic ball, spring-return |
| Vapor return | Cryogenic butterfly |
| Drain/vent small bore | Cryogenic globe per API 602 execution |
The Three Requirements That Have to Coexist
What makes bunkering valve selection unusual is that three demanding requirements apply to the same component simultaneously, and satisfying two of them is not enough.
Cryogenic capability. LNG arrives at roughly −162 °C, so extended-bonnet construction, austenitic stainless bodies, cryogenic-rated seats and a cryogenic type test are baseline, not premium options.
Fire-safe qualification. A bunkering transfer point handles a flammable cryogenic fluid in an area with ignition sources. Valves in the transfer path are normally required to hold a fire-test certificate as well as the cryogenic qualification — two separate type tests on the same design.
ESD compatibility. Emergency shutdown valves must close within a specified time on loss of signal, air or power, and must be proven to do so. That drives actuator sizing, air volume, and the fail-action design, and it must be demonstrated at commissioning rather than assumed from a datasheet.
Testing and Documentation to Insist On
- Helium leak testing rather than air or water — the only meaningful acceptance test at these temperatures and for these fluids.
- Cryogenic type test certificate covering the specific size and class supplied, not the family.
- Fire test certificate with its standard and edition stated.
- ESD closure time verification at the design air supply pressure, recorded at commissioning.
- Cleanliness documentation — hydrocarbon-free preparation with capped ends, and packaging that survives the site.
- Material certificates including impact test results at the service temperature.
Why These Projects Look Restrictive
Bunkering specifications often read as though they are brand-restricted. Usually they are not — they are qualification-restricted. The combination of cryogenic type testing, fire-safe certification, ESD proof and marine or classification-society acceptance narrows the field to designs that already carry all of that evidence. The way to open a specification is to supply the qualification package early, not to argue the specification is unreasonable.
Frequently Asked Questions
Why do bunkering specs demand helium seat tests?
Ambient water/air tests say little about tightness at −162 °C; helium at cryogenic temperature is the only meaningful acceptance for this service.
Are these projects brand-restricted?
Usually specified by standard and class approval rather than brand — which suits our brand-agnostic, spec-driven supply model.
Working on an LNG bunkering, satellite station or small-scale LNG project in Canada, Europe or Türkiye? Send us the valve list.
