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 and two-screw pumps for fuel and lube oil transfer and 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.
• Framo — hydraulic-driven submerged cargo pumps.
• Marflex — deepwell 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 — Naniwa, IHI, various. Used for specific fuel/lube circulation and hydraulic circuits.
4. Deepwell / cargo pumps — Framo, Marflex, Shinko, Naniwa. Component families are specific: hydraulic motors on the hydraulically driven pumps, electric drive motors on the rest, mechanical seals, cofferdams, cargo-line valves. On these the cofferdam and its monitoring are part of the safety case rather than an accessory, so a seal line on a cargo 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. 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 038N4 IVBP), fluid, and whether OEM or an aftermarket equivalent is acceptable. It is worth adding the fluid the pump handles now if it has changed, because a set selected for heated residual fuel and run on low-sulphur distillate wears differently and 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 runs hot in a pump that sees thermal growth along the shaft.
• Gasket and O-ring kits — often available as OEM service kits or as verified alternatives when the material spec is confirmed.

Identity evidence — pump-specific fields

1. Pump make and full model designation — from the nameplate. The full designation with all suffix codes matters (e.g. Imo ACE 038N4 IVBP, DESMI NSL125-330, Iron Pump DNP80-32).
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 — always useful.
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.

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