Fukui Safety Valve
Spare Parts Requests
Pilot-operated safety & relief valves - PSL-MD low-pressure type - hydrogen systems
The Fukui valves behind most safety-valve enquiries
Fukui Seisakusho Co., Ltd. is a Japanese manufacturer of safety and relief valves for marine applications. Its equipment reaches ships on duties where the protected system cannot tolerate a valve that opens late, leaks early or fails to reseat: liquefied-gas cargo tank protection, engine-room pressure relief, and the emerging hydrogen dual-fuel and liquefied-hydrogen carrier systems now appearing on newbuildings. Those duties differ in pressure, in medium and in the paperwork that follows the valve, which is why a spare-parts request is far easier to quote once the valve itself has been identified rather than described by its function on board.
Pilot-operated safety and relief valves
In a pilot-operated valve the setting is held by a small pilot rather than by a large spring bearing directly on the main disc. The pilot senses system pressure and controls the loading on the main valve, which is what allows the valve to stay tight close to its setting and then open decisively. It also means the pilot, not the main body, is the part most often on an enquiry.
PSL-MD low-pressure type
The PSL-MD is Fukui's low-pressure pilot-operated type for liquefied-gas cargo tanks. Cargo tank protection sits in a narrow band: the valve has to hold tight against normal tank pressure and still relieve without hesitation, so the condition of the pilot, the seat and the soft seals matters more here than raw size does.
Engine-room pressure relief
Engine-room relief duty is the second documented application. These valves sit on machinery-space systems rather than on cargo, and they are usually opened as part of a planned overhaul rather than after an incident, which is why requests for them tend to arrive as kits and inspection spares rather than as single emergency items.
Ultra-high-pressure relief valves
Fukui also develops ultra-high-pressure relief valves for hydrogen dual-fuel engines. This is newer equipment on a small number of vessels, and enquiries around it are best handled with the valve identity and the system it serves stated in full, since the installed base is not yet something a buyer can assume anything about.
ClassNK hydrogen work
Fukui signed a memorandum of understanding with ClassNK in 2023 covering safety valves for hydrogen dual-fuel engines and liquefied-hydrogen carriers, and type approval under that work was issued in 2025. For a buyer the practical point is that hydrogen-side valves carry a documentation trail that a buyer should expect to reference when the valve is opened.
Approvals across five societies
Fukui valves are documented as type-approved by LR, BV, DNV-GL, ABS and ClassNK. Which society issued the certificate for the valve in front of you is worth stating in the enquiry, because the survey the overhaul is attached to, and the record the ship has to keep afterwards, follow that certificate rather than the valve body alone.
Why a safety valve request begins with its setting, not its size
A safety valve is not a fitting. It is a certified device whose whole purpose is to open at a recorded pressure and to close again cleanly once the system has recovered, and every part inside it exists to hold or restore that behaviour. That single fact reorganises the enquiry. On a pump or a cooler the part number leads and the duty follows; on a safety valve the recorded setting leads, because the spring, the pilot and the seating arrangement were selected for that setting on that valve, and a component correct for one execution of a series can be wrong for another that looks identical from the outside.
The parts that wear are the parts that decide when the valve lifts and how it sits down afterwards. The disc and seat form the tightness couple, and they wear as a pair rather than individually: a disc renewed against a marked seat rarely returns the valve to a clean, quiet hold near its setting. Guides and spindle components keep the disc square through lift and reseat, so wear there shows up as behaviour rather than as leakage - a valve that chatters, or that lifts unevenly, is often reporting a guiding problem rather than a seat problem. On pilot-operated valves the pilot carries small internals and soft seals of its own, and because the pilot governs the main valve, a tired pilot is felt as a main-valve fault.
Soft parts deserve their own line in the request. Bellows, O-rings and gaskets age with temperature, medium and time rather than with the number of lifts, so they are normally renewed as a group when the valve is opened, whatever the inspection finds elsewhere. On cargo and gas service the medium argues for particular soft-seal choices, so the fluid and its service temperature belong in the enquiry alongside the valve identity - not as a specification to be quoted against, but as the context that stops the wrong soft-seal kit being offered.
Timing is the last piece, and on ships it is rarely arbitrary. Safety valve overhaul is normally tied to set-pressure verification and to class survey intervals, so a request for internals often accompanies a re-setting or re-certification job rather than a breakdown. Saying so changes how the request is structured: it tells the desk that a full series overhaul kit may be more useful than three loose items, that the pilot is likely to be renewed with the main valve, and that the survey rather than the sailing schedule is the fixed point in the discussion.
Fukui safety valve components that appear on RFQ lines
The groups below follow the order in which an opened safety valve is inspected - pilot first, then the main valve seating couple, then springs, soft parts and guiding components - so each RFQ line can carry a drawing item number beside the description.
- Pilot assemblies for pilot-operated valves
- Pilot spare kits and pilot internals
- Main valve discs
- Main valve seats
- Disc and seat sets quoted as a matched pair
- Spring assemblies matched to the recorded set pressure
- Bellows
- O-rings, gaskets & soft-seal kits
- Guide components
- Spindle components
- Overhaul kits grouped by valve series
Marine globe valve — general arrangement
A licensed photograph of Fukui equipment was not available at publication, so this technical reference illustrates the general arrangement shared by this equipment class.
Illustrative technical reference, not a photograph of Fukui equipment or a Vessel Core installed reference — a licensed photo of this maker's equipment was not available. Vessel Core has no dealership, distribution or partnership agreement with Fukui; it operates as an independent spare parts supplier.
Turning a valve nameplate into a quotable line
Part numbers for safety valve internals are often missing on board, because the valve is carried in the ship's records as a certified assembly rather than as a list of items. The nameplate, the certificate and a handful of photographs usually carry more identifying information than a stores description does, and together they are enough to begin cross-checking.
- Valve series or type designation read from the body or nameplate
- Serial number and year of manufacture where the plate is legible
- The set pressure recorded for that valve on its certificate or in the ship's records
- Service protected: liquefied-gas cargo tank, engine-room relief line, fuel or gas system
- Pilot-operated or conventional execution
- Classification society named on the certificate
- Whether the work is a routine overhaul, a re-setting or a class survey item
- Medium and its service temperature, for soft-seal selection
- Photographs of the valve body, nameplate and any tag plate, taken square-on
- Photographs of the pilot, the disc and seat and the bellows where the valve is open
- Sectional-drawing item numbers from the valve manual
A certified valve asks more of an enquiry than a loose fitting does.
Two facts drive everything below: the valve holds a recorded setting, and the job that opens it is usually attached to a survey. Together they change which questions come first, which items travel together on a quotation, and why a request that names only a size and a maker is hard to answer well.
Setting asked before part number
The recorded set pressure of the valve is asked for early, because spring assemblies and pilot internals follow the setting rather than the nominal size. Requests that give only a maker and a size are queried back before any supplier outreach.
Pilot and main valve read together
On a pilot-operated valve the pilot governs the main valve, so a main-valve complaint is often a pilot matter. The pilot assembly and its spare kit are raised alongside the main valve items rather than after them.
Disc and seat treated as a pair
The seating couple wears together, and renewing one half against a marked mating face rarely restores a quiet hold near the setting. Where the execution allows it, the disc and seat are put on the enquiry as one line.
Soft parts renewed as a group
Bellows, O-rings and gaskets age with medium, temperature and time. They are quoted as a soft-seal group for an opened valve, with the fluid and its service temperature confirmed first so the compound suits the duty.
Guiding checked before the seat is blamed
Chatter and uneven lift usually point at guides and spindle components rather than at the seating faces. Those parts are raised as their own, much smaller line before a conclusion is drawn about the seating couple.
Survey timing stated up front
Because safety valve work is normally tied to set-pressure verification and class survey intervals, the enquiry states whether the job is an overhaul, a re-setting or a survey item. That decides whether a series overhaul kit or a short list of items is the better structure.
Fukui safety valve enquiries - recurring questions
Can Vessel Core quote Fukui safety valve parts without a part number?
Often yes. The valve series or type designation read from the body or the nameplate, the serial number, the service the valve protects and the set pressure recorded for it are usually enough to begin structuring the RFQ. Where the valve is already open, photographs of the pilot assembly, the disc and seat and the bellows narrow the request further before a supply route is reviewed.
What information is needed for a Fukui pilot-operated safety valve enquiry?
The valve series or type designation, the serial number where the nameplate is still legible, the service protected such as a liquefied-gas cargo tank or an engine-room relief line, and the set pressure recorded for that valve. It also helps to state whether the pilot is being renewed together with the main valve, and whether the job is a routine overhaul, a re-setting or a class survey item, since safety valve work on ships is normally tied to set-pressure verification and survey intervals.
Which parts are usually requested when a Fukui safety valve is overhauled?
Pilot assemblies and pilot spare kits on pilot-operated valves, main valve discs and seats, spring assemblies matched to the set pressure, bellows, O-rings, gaskets and soft-seal kits, and guide and spindle components. Many yards prefer an overhaul kit grouped by valve series as a single line, with individual items added once the opened valve has been inspected.
Is Vessel Core connected to Fukui Seisakusho?
No. Vessel Core operates as an independent marine spare parts supplier, sourcing and quoting components on its own account. No dealer, distributor or partner appointment from Fukui Seisakusho Co., Ltd. is associated with this page or with the parts described on it. The Fukui name and the PSL-MD designation appear here only so that a buyer can match a valve already installed on board to a parts list.
Send the nameplate and the recorded setting.
List the valve series or type designation, the serial number, the service it protects, the set pressure recorded for it, the components required and the port. Pilot assemblies, discs and seats, spring assemblies, bellows and soft-seal kits are then quoted as separate lines, so the ship can decide what to open now and what to carry as a spare before the next survey.
