Marine pumps spare parts — a sourcing guide for Imo, Naniwa, DESMI, Iron Pump and other common makers

Common commercial marine pump makers

• Imo AB (CIRCOR) — three-screw pumps for fuel oil supply and transfer and for lube oil circulation.
• DESMI — centrifugal pumps for ballast, bilge, fire, cooling and general service.
• Naniwa Pump — Japanese OEM for cargo pumps and engine-room service pumps on Japanese-built vessels.
• Iron Pump — Danish OEM known for cooling water and general service pumps.
• Allweiler (CIRCOR) — three-screw, progressive-cavity and centrifugal pumps.
• Shinko Industries — Japanese cargo, ballast, cooling and general service pumps.
• Taiko Kikai — Japanese OEM for general engine-room and cargo pumps.

Other names sometimes seen: Sulzer, KSB, Grundfos (utility applications), Hamworthy (specialised). On a Japanese-built vessel the engine-room service pumps are frequently a Japanese maker even where the main machinery is European, and the reverse holds on European builds, so the pump is identified from its own plate rather than from the shipyard or the engine builder.

The four pump-type families

1. Screw pumps — Imo, Allweiler, Naniwa. Used for fuel oil, lube oil, hydraulic oil circulation. Component families: rotors (main and idler screws), pump body, mechanical seals, bearings. The screws are supplied and quoted as a matched set rather than individually, because the seal that holds differential pressure is formed by the meshing screws and the close-fitting housing bore together, and a single new screw in an otherwise worn set and bore does not restore it.
2. Centrifugal pumps — DESMI, Iron Pump, Shinko, Taiko, KSB. Used for cooling water, ballast, bilge, general service. Component families: impellers, wear rings, mechanical seals, shafts, bearings. Wear rings deserve their own line in an enquiry rather than being folded into an impeller order: the ring clearance is what limits internal recirculation, so a worn ring costs capacity and efficiency first and a few per cent of head after that, which reads on a gauge as the same complaint a worn impeller produces. Renewing one and not the other leaves half the problem in place.
3. Positive displacement (rotary/gear/vane) pumps — Taiko Kikai and Naniwa (gear pumps), DESMI (ROTAN internal gear pumps) and others. Used on fuel and lube oil transfer, on sludge and other viscous duty, and on hydraulic circuits. DESMI notes that the volumetric efficiency of an internal gear pump rises with viscosity, so the fluid and its working temperature belong in the request alongside the plate data.
4. Deepwell / cargo pumps — Shinko, Naniwa, Taiko Kikai. Two different builds share this heading. Shinko's KV cargo oil pumps are vertical, single-stage, double-suction centrifugal pumps, and Naniwa lists cargo pumps of centrifugal and two-rotor screw type among its pump-room packages; these stand in the pump room rather than in the tank. Taiko Kikai's range also includes submerged deepwell pumps, among them a version for liquefied gas. Component families follow the build: impellers or rotor sets, wear rings, mechanical seals and bearings on a pump-room unit; drive motor, shaft seals and, on a hydraulically driven submerged pump, the cofferdam. Where a cofferdam is fitted, it and its monitoring are part of the safety case rather than an accessory, so a seal line on that pump is written with the cofferdam arrangement stated and not only the shaft size.

Common RFQ line categories

• Mechanical seals — a recurring pump RFQ. Send the pump make and model, seal arrangement (double/single, cartridge/component), shaft diameter, fluid, pressure and temperature. John Crane, EagleBurgmann and Chesterton may supply the seal even when the pump has another OEM. Two further points decide whether an offer is usable. The face pairing and the elastomer are the specification, not the shaft diameter: a carbon against silicon carbide pair and a silicon carbide against silicon carbide pair are different seals for different duties, and an elastomer chosen for fresh water is not chosen for hot fuel oil. Imo's own three-screw designation shows it: on an ACE pump the shaft-seal letter V marks the Lube Line execution with a carbon face, and T the Fuel Line execution with silicon carbide against silicon carbide. And a cartridge seal and a component seal are different fitting jobs even at the same size, because a cartridge arrives set and a component seal is set on installation.
• Impellers — for centrifugal pumps. Buyer should send: pump make/model, impeller diameter, material spec (bronze, cast iron, stainless), and whether closed/semi-open/open. Measure the diameter rather than reading it from the catalogue. Impellers are routinely trimmed to duty against the pump curve when the pump is selected and built, so the one in the casing is often smaller than the nominal size for that model, and a replacement at full diameter changes the head the pump delivers. On sea-water duty state the casing material as well, since the impeller and the casing are selected as a pair and a mismatch sets up galvanic attack on whichever of the two is less noble.
• Screw sets and rotor sets — for screw pumps. Buyer should send: pump make/model, full pump designation from the nameplate (e.g. Imo ACE 025N3 NVBP), fluid, and whether OEM or an aftermarket equivalent is acceptable. It is worth adding the fluid the pump handles now if it has changed. Since MARPOL Annex VI regulation 14 capped fuel sulphur at 0.10% inside emission control areas and, from 1 January 2020, at 0.50% elsewhere, many sets selected for heated residual fuel now run on low-sulphur distillate. The thinner fluid leaks back more across the screw clearances, and Imo's own ACE data sheet lowers the permissible differential pressure as viscosity falls, so such a set may be being replaced early for that reason rather than for age.
• Bearings and shafts — typically OEM part number if available; otherwise bearing designation (SKF/FAG/NSK number) plus shaft diameter. Copy the suffix as well as the base number: the internal clearance class and the cage material are carried in the suffix, and a bearing supplied with the standard clearance where a wider class was specified can lose its running clearance and run hot. Bearing makers call for the wider classes with interference fits and where the shaft and inner ring run warmer than the housing, as on a pump handling heated fuel or hot water; growth along the shaft is taken by the locating and non-locating bearing arrangement, not by the clearance class.
• Gasket and O-ring kits — often available as OEM service kits or as verified alternatives when the material spec is confirmed. Check the elastomer against the fuel the pump handles now, not the fuel it was built for: after the move to sulphur-compliant fuels Taiko Kikai reported the standard NBR stator of its single-screw pumps swelling in some of them and recommended FKM instead, and the same question is worth asking of the O-rings and seal elastomers in any fuel pump.

Identity evidence — pump-specific fields

1. Pump make and full model designation — from the nameplate. The full designation with all suffix codes matters. In Imo's own sample code, ACE 025N3 NVBP, the characters after the size give the rotor lead, the design generation, the body material, the shaft seal, the mounting and the relief valve, so two pumps of the same frame size can differ in every one of them.
2. Serial number — required for many OEMs to cross-reference to the build spec.
3. Application — fuel oil, lube oil, sea water, fresh water, ballast, bilge, hydraulic. Same base pump can be built with different materials and seals for different fluids. Where a pump has been re-tasked in service — a general service pump put on to a different duty after a conversion — say so, because the plate then describes the pump as built rather than the pump as used.
4. Fluid, temperature, pressure — critical for seal, impeller and wear-ring selection. Suction condition is worth adding on any pump that has been cavitating, because pitting on an impeller inlet is a symptom of the installation rather than of the part, and replacing the impeller without saying so simply restarts the clock.
5. Photo of the nameplate — the whole plate in one square-on shot without flash glare, so the type string, serial number and, where shown, build year are read from one image rather than retyped; if the motor carries its own plate, photograph that too.
6. Photo of the seal cavity / impeller housing — if the RFQ is a seal or impeller replacement and no drawing is available. A photograph taken square-on with something of known size in frame is more useful than a measured figure recalled later, and it also shows how the seal is retained, which is often what separates two otherwise identical part numbers.

OEM route vs verified alternative

For mechanical seals, the pump OEM may specify a seal made by John Crane, EagleBurgmann, Chesterton or another specialist. The controlling question is the documented seal specification, not the name alone. For impellers, wear rings and screw sets, material and dimensional tolerances must be confirmed for the exact pump. Gasket and O-ring alternatives should be considered only after material, dimensions, duty and warranty requirements are verified.

Vessel Core structures the RFQ to make each choice visible per line. See the RFQ case notes for the pattern.

What we do not claim before an RFQ is reviewed

Vessel Core does not quote pump-part prices, lead times or supply route before the specific pump, application and identification data are confirmed. A quotation prepared without the complete pump designation and fluid or duty information should be treated as preliminary. Where the nameplate has corroded past reading — common on sea-water pumps, which is where most of these enquiries come from — the casing casting marks, the shipyard plate and a photograph of the removed component are usually enough to open the review.

How to send the RFQ

Use the RFQ form. Attach photos of the pump nameplate and, where relevant, the seal cavity or impeller housing. If the pump has both an OEM plate and a shipyard plate, send both.

Frequently asked questions

Which marine pump families recur in RFQs?

Frequently encountered makers include Imo, Naniwa, DESMI, Iron Pump, Allweiler, Shinko and Taiko Kikai. Screw-pump families recur in lubricating-oil duties, while centrifugal-pump families recur in cargo, ballast and cooling duties; confirm the exact installed type and service.

What is the identity anchor for a marine pump RFQ?

Pump maker + model + serial number + impeller diameter + casing material + mechanical seal spec. All from the pump nameplate or vessel documentation. For screw pumps, add the rotor set material and pressure/flow rating.

Should I order the OEM mechanical seal or an aftermarket equivalent?

OEM and alternative seal routes are both available for some pumps. Before selecting a John Crane, EagleBurgmann, Chesterton or cross-referenced seal, confirm the exact seal arrangement, shaft diameter, face-material pairing, elastomers, fluid, temperature and pressure against the original specification.

What about pump mechanical seals that are on OEM shafts?

Some pumps use unit-specific shaft or seal-chamber geometry, so a generic seal may not fit. Confirm the drawing and dimensions before selecting a route. Any proposal to modify a shaft or chamber is an engineering change and requires a separate technical assessment.

How do I identify a marine pump when the nameplate is unreadable?

Use vessel documentation, previous purchase orders and the relevant spare-parts book to recover the identity. Send clear photos of the complete pump, both connection ends, the driver plate and any casting or stamped references so the evidence can be cross-checked.

Related reading

• Marine turbocharger spare parts sourcing guide
• Marine fuel injection spare parts sourcing guide
• Marine separators spare parts sourcing guide
• Marine lubricating-oil system spare parts guide
• RFQ evidence guide
• RFQ evidence checklist
• RFQ case notes