A ship is a plant that moves: IMPA and ISSA codes versus maker part numbers, ISM critical spares, requisition platforms and MTML, the "ship spares in transit" customs status with its legal basis, consolidation hubs, delivery to the agent, and the vessel-class standing list that turns urgent buying into an account.
The chain, in order: a chief engineer or master raises a requisition in the ship's planned maintenance or purchasing system; the technical superintendent approves it; the purchasing office sends it as an RFQ to three to five vendors, usually through a platform; quotes come back and are compared on price, lead time and whether the vendor can hit the next useful port; a purchase order is issued; the vendor ships to a forwarder or hub; the forwarder routes the consignment to the port of call marked "ship spares in transit"; the local agent clears it and delivers to the quay, the anchorage launch or the vessel's gangway; the master signs for it; the vendor invoices the manager.
Every link in that chain is scheduled against the ship's itinerary. The purchasing office is not asking "how fast can you ship"; it is asking "can you be at the agent in Rotterdam by the 14th, or in Singapore by the 29th". The right answer is often the later port with a consolidated box rather than the earlier port with a courier parcel, which is why marine purchasing rewards suppliers that plan deliveries against itineraries instead of promising speed.
Two terms that keep the chain honest. Delivered to agent means the consignment is in the agent's warehouse, cleared, before the window closes. Landed on board means the master has signed for it. Vendors control the first; agents and tides control the second; the purchase order should say which one the vendor is responsible for, with the Incoterm to match (usually DAP agent's warehouse at the named port).
| Number | What it identifies | Where it comes from | Who can quote it |
|---|---|---|---|
| Maker part number | A specific component from the component maker: a pump seal, a contactor, a bearing, a sensor, a valve | The component's own plate or the equipment maker's parts list | Any distributor of that maker, by cross-reference; equivalents possible where nothing binds the position |
| Equipment maker's plate and item number | A part of a main or auxiliary engine, a separator, a compressor, a thruster, as drawn by the equipment maker | The engine maker's instruction book: plate (drawing) number and item or position number, often with the engine serial number | The equipment maker's parts desk or authorised agent; standard components inside the assembly can be identified from their own markings (the two-kit rule) |
| IMPA code | A generic store item defined in the IMPA Marine Stores Guide: a 6-digit code whose leading digits place the item in a section, across a catalogue of more than 50,000 items maintained by the International Marine Purchasing Association since 1978 | The Marine Stores Guide and the purchasing system's templates built on it | Chandlers and stores suppliers worldwide; the code defines the item, not a maker |
| ISSA code | A generic store item in the Ship Stores Catalogue of the International Shipsuppliers and Services Association, the supplier-side catalogue chandlers often stock by | The ISSA catalogue | Chandlers; the two catalogues overlap heavily but divide some product families differently, so a one-to-one mapping cannot be assumed |
The rule that follows: technical spares travel on maker numbers, engine parts on plate and item numbers with the engine serial, stores on IMPA or ISSA. A requisition that puts an IMPA code on a technical spare gets a generic item; one that puts a description where a maker number belongs gets a clarification email that costs a port call. Fleets whose requisition templates carry both codes where they exist, and the maker number where it exists, get the fewest clarification rounds.
Owners with technical management in house, and third-party ship managers who run technical and purchasing functions for owners, do most of the buying; the largest third-party managers run several hundred vessels each from purchasing offices in Singapore, Hamburg, Hong Kong, Limassol, Mumbai, Manila and the Nordic ports. A technical superintendent owns a handful of ships and approves their requisitions; a purchasing office buys for the fleet; the crew raises requisitions and receives the goods.
The spend is many small lines across many makers, which is the same shape as a plant's long tail, with one difference: a plant can collect from its local stockist tomorrow and a ship cannot. That difference is why consolidation, itinerary planning and the agent matter more at sea than ashore, and why the number of vendors a fleet keeps is a cost in itself. Each vendor is an onboarding, a platform connection, a payment run and a set of delivery habits to learn.
| Category | Examples | What binds the purchase | Route |
|---|---|---|---|
| Main and auxiliary engine spares | Pistons, rings, liners, bearings shells, injectors, fuel pumps, turbocharger parts | Engine maker's parts list by plate and item number; class rules for propulsion machinery; maker's service letters; warranty on newer tonnage | Engine maker's parts desk or authorised agent; standard components inside (seals, bearings, O-rings) identifiable by their own designations |
| Auxiliary machinery | Pumps, compressors, separators, purifiers, boilers, steering gear, thrusters | Equipment maker's parts list; class survey items; the two-kit rule | OEM desk for maker-only parts; part-number distributors for standard lines |
| Electrical and automation | Contactors, breakers, drives, PLC and I/O, sensors, alarms, navigation and communication spares | Maker part numbers; class type approval on essential-service equipment; the lifecycle status of control hardware | Part-number distributors; makers' channels for type-approved items |
| Safety equipment | Lifeboat and davit parts, liferafts, fire-fighting systems, EEBDs, immersion suits, pyrotechnics | SOLAS; type approval; annual and five-yearly servicing by approved service stations; expiry dates | Approved service providers and type-approval holders |
| Deck and cargo gear | Wire ropes, mooring lines, blocks, shackles, hatch-cover parts, crane spares | Certificates for lifting gear and mooring lines; class for hatch covers and cranes | Specialist suppliers with certificates per item |
| Stores | Tools, paints, galley, cabin, cloth and linen, lamps, fasteners, pipe fittings | IMPA and ISSA codes | Chandlers at the port of call; consolidated stores suppliers |
| Chemicals and water treatment | Boiler and cooling-water chemicals, tank cleaners, ballast water treatment consumables and UV lamps | Safety data sheets; dangerous-goods rules; type approval for BWTS lamps and parts | Chemical suppliers; BWTS maker's listed spares |
| Lubricants | Cylinder and system oils, greases | Oil majors' marine networks; maker approvals per engine | Lubricant suppliers' port networks |
| Provisions | Food, bonded stores | Port supply | Chandlers |
The ISM Code's section 10.3 requires the company to identify equipment and technical systems whose sudden failure may result in hazardous situations and to promote their reliability, which in practice produces the critical spares list per vessel: what must be on board, in what quantity, and who checks it at audit. The classification societies' rules and recommended spare parts lists for propulsion machinery feed the same list on the machinery side. Those are the lines a manager buys ahead of the window; everything else is bought to it.
The planned maintenance and purchasing systems that generate requisitions (among them AMOS, NS Enterprise, Danaos, ShipNet and SERTICA) hand them to trading platforms. ShipServ, the largest, was carrying about USD 6 billion of transactions a year for some 300 buyer companies when Marcura acquired it in 2023; Procureship serves many owners and managers from Greece outward; others serve particular fleets. A supplier registers on the platform, is linked to the buyers that choose to trade with it, receives RFQs with line numbers and codes, and returns quotes and order confirmations in the same structure.
MTML, the Marine Trading Markup Language, is the XML standard underneath: published in 2000 by MTML.org on the foundation of IMPA's Electronic Trading Standard Format, it carries requisitions, RFQs, quotations and orders between buyers' systems and suppliers' systems so that line numbers, codes, quantities and prices arrive as data rather than as PDF attachments. For purchasing that means three things: the supplier's quote lands in the buyer's system as lines that can be compared; the order comes back as data the supplier can pick against; and nothing is retyped.
What a fleet should expect of a supplier here: registration on the fleet's platform, quotes returned in the platform's structure in the RFQ's line order, order confirmations with delivery port and window restated, and invoices that carry the PO number the manager's accounts payable system matches on.
What it is. A customs status for goods destined for a vessel in international traffic: the consignment moves through a customs territory to the port and on board without being imported into that territory. Practice differs by country and by the vessel's status in the port; a foreign-flag vessel on an international voyage generally qualifies and a locally registered vessel in its home port generally does not. In the EU, Article 148 of the VAT Directive 2006/112/EC exempts the supply of goods for the fuelling and provisioning of vessels used for navigation on the high seas and the supply, repair and maintenance of such vessels and of equipment incorporated or used in them, which is the legal basis for VAT-free delivery of spares to qualifying vessels in EU ports; customs duty relief follows the customs procedures of the port state.
How a consignment has to be marked and documented. Vessel name and IMO number, "SHIP SPARES IN TRANSIT", port of delivery, agent's name and address, the manager's PO number and the vessel's ETA, on the packages, the air waybill or bill of lading, the commercial invoice (with HS codes and country of origin per line) and the packing list. The agent is appointed in advance and told what is coming; the forwarder is told the vessel's window; the master receives the delivery note and signs the receipt that closes the vendor's responsibility.
Where it fails. Wrong or missing commodity codes; packages that do not carry the vessel and IMO; a consignment that arrives before the agent has been appointed; a vessel whose port status does not qualify, so duty and VAT are charged on arrival; dangerous goods (lithium batteries in instruments, aerosols, chemicals) shipped without declarations and held by the airline; and consignments that arrive after the ship has sailed, which then chase the vessel at the buyer's cost. Fines, holds and destruction are the outcomes customs authorities reserve for consignments declared wrongly.
Hubs. Fleets and marine forwarders consolidate through a small number of hubs with marine-spares expertise and frequent connections to the ports ships actually call at: Rotterdam, Antwerp and Hamburg in Europe, Singapore in Asia, Dubai for the Gulf, Houston for the US Gulf, Busan and Shanghai for the Far East. A supplier that delivers to the fleet's hub, packed and marked for the vessel, lets the fleet decide which port call takes the box.
Dry dock is a different regime. Spares for a yard period are delivered to the yard, often imported by the yard or the owner's agent under the yard's procedures, and are planned months ahead against the docking specification. The port-call window still applies, but the window is the docking and the agent is the yard.
Bound to the maker or the approval. Propulsion and steering machinery parts covered by class rules and makers' service letters; type-approved safety equipment; ballast water treatment lamps and parts named in the system's IMO and USCG type approval; parts under warranty on new tonnage; navigation and communication equipment under its type approvals. For these the requisition names the maker and the part, and the supplier quotes that or an alternative the maker has listed, nothing else.
Open to equivalents. Standard components with their own designations: bearings, mechanical seals in standard dimensions, O-rings and gaskets, filter elements, belts, contactors and breakers to the same ratings, sensors to the same specification, valves and fittings to the same standard and material grade. Here an equivalent to identical specification and certification is a legitimate saving, declared on the quote next to the requested maker, never swapped silently, and the certificate requirement per line (class, EN 10204 3.1, type approval) travels with it.
The chief engineer decides, the superintendent approves, and the supplier's job is to make the choice visible on the quote rather than to make it for them.
Sister ships carry the same machinery, so a fleet's demand is per class, not per vessel. A manager with forty ships in six classes keeps six spares lists; a class list has a few hundred technical lines that repeat every year (filters, seals, bearings, gaskets, lamps, sensors, contactors, belts, hoses) and a critical spares register that is checked at every audit.
The vessel-class standing list: repeat lines per class with annual quantities, certificate requirement per line, maker-bound or equivalent-open per line, priced once a year on unit rates with quantity bands, called off per vessel and per port call. Three things follow from it:
Commercial invoice with HS codes and origin per line, and the PO number; packing list with vessel name and IMO number; delivery note for the master's signature; class certificates where the line requires them (DNV, ABS, Lloyd's Register, Bureau Veritas, RINA, ClassNK and the others); EN 10204 3.1 on material-critical lines; type-approval references on BWTS and safety lines; certificates of conformity for the rest; safety data sheets and dangerous-goods declarations for chemicals, batteries and aerosols; export-control classification where the port state asks. The documents go in the box and, as data, to the purchasing office; a certificate that arrives three emails after the ship has sailed is a certificate the audit will not find.
A supplier that reports its own figures on the first five is a supplier the office can plan around.
Copy it, fill it in and send it to sales@cballast.com, or raise it through the platform your fleet trades on. It works with any supplier, and it is built so that one vessel's requisition or a whole class list can be priced firm without a clarification round and delivered to the window.
1. WHO YOU ARE owner or manager, legal entity, registration or VAT no., role, company-domain email 2. VESSEL name, IMO number, flag, class society; vessel class and sister ships if the list is per class 3. WINDOW port of delivery, ETA and ETD, agent's name and contact; alternative port if the first is missed 4. LINES maker part number, or equipment maker's plate and item number with engine serial, or IMPA/ISSA code; description; quantity with unit; line numbers as in your system 5. BINDING maker-bound (class, type approval, warranty) or equivalent-open, per line 6. DOCUMENTS class certificate, EN 10204 3.1, type-approval reference, certificate of conformity, SDS, per line 7. DELIVERY DAP agent's warehouse or delivery on board; hub consolidation preferred or direct; dangerous goods flagged 8. CHANNEL platform and buyer account, or email; MTML or PDF; PO and invoice requirements 9. STANDING LIST repeat lines per vessel class with annual quantities, if you have them, in any format 10. ACCOUNT one-off, annual standing list or framework; payment terms proposed
What comes back from our desk: each line priced in your line order with maker, part number and certificate status; equivalents, where open, declared next to the requested maker with the specification they are offered to, never swapped silently; lead time per line against your window, with a proposed port if the first window cannot be met; packing marked for the vessel and IMO with "ship spares in transit" where the port qualifies; documents per line in the box and as data; and, for standing lists, unit rates with quantity bands and a delivery plan per class.
How accounts work at cballast. Every new account is vetted at onboarding. The first order is prepaid. After that, established accounts move to credit terms and substantial repeat-account discounts, and ship managers trading through a platform are invoiced against the platform PO. We work on quote and invoice, not a checkout. We do not compete on same-day delivery; we compete on delivery that holds, fair terms and agreements worth signing, which at sea means delivery to the window, in a box the agent can clear. The buyers we are built for are owners and managers with recurring demand across a fleet. We do not quote broadcast lists with no named vessel and end user.
Standards and sources referenced: ISM Code section 10.3; IMPA Marine Stores Guide; ISSA Ship Stores Catalogue; MTML (Marine Trading Markup Language, mtml.org); Directive 2006/112/EC Article 148 (VAT); SOLAS; classification society rules (DNV, ABS, Lloyd's Register, Bureau Veritas, RINA, ClassNK); EN 10204; IMO BWM Convention.
Questions on a code, a window, a customs marking or how to build a class list are welcome at sales@cballast.com. We answer whether or not you buy from us. Requisitions, class lists and marine RFQs go to sales@cballast.com or through your fleet's platform.