If you have ever read a ship's stores requisition, you have seen them: neat rows of six-digit numbers next to every item. Those are IMPA codes, and they are the closest thing the maritime supply industry has to a universal language. Understanding them is one of the fastest ways to reduce ordering errors, speed up quotations, and avoid the wrong part arriving at the wrong port.
What Is an IMPA Code?
An IMPA code is a standardised six-digit number that identifies a specific marine store item. The system is maintained by the International Marine Purchasing Association (IMPA) and published as the IMPA Marine Stores Guide, which has become the de-facto global catalogue for ship chandlery. Every code maps to one clearly defined product, with a standard description, unit of measure and, often, a reference image.
Because the code is universal, a purchaser in Greece, a chandler in Singapore and a captain on a vessel off Fujairah can all refer to exactly the same item — no translation, no ambiguity, no "I thought you meant the other type of valve."
How the Six Digits Are Structured
The IMPA code is built from logical blocks:
- The first two digits indicate the main category (for example, the 11-series covers cleaning materials, the 17-series covers safety equipment, the 19-series covers electrical equipment, the 59-series covers provisions).
- The middle digits narrow it to a sub-group within that category.
- The final digits identify the individual item and its specification.
So when you see a code, you can often tell at a glance which "world" it belongs to before you even read the description.
IMPA vs ISSA: What's the Difference?
You will also hear about ISSA codes, maintained by the International Ship Suppliers & Services Association. Both systems do the same job — standardised identification of marine stores — and many catalogues cross-reference the two. IMPA is the more widely used standard for general stores and provisions; some suppliers still quote ISSA references, so it is worth keeping a cross-reference handy.
Why IMPA Codes Save Real Money
Standardised codes are not just tidy — they have a direct operational payoff:
- Fewer wrong deliveries. A description like "rope, 24mm" is ambiguous; an IMPA code is not.
- Faster quoting. Suppliers can price a coded requisition in minutes instead of emailing back clarifying questions.
- Cleaner comparison. When every quote references the same code, you compare like-for-like instead of guessing whether two suppliers are offering the same product.
- Better budgeting. Historical spend by IMPA category reveals exactly where the money goes.
How GDS Uses IMPA Codes
The GDS - Global Digital Shipping platform is built around a catalogue of more than 28,000 coded marine items across dozens of categories. When a vessel raises a requisition, every line is tied to its standard code, so suppliers quote against an unambiguous specification and buyers compare quotes side-by-side. The result is faster turnaround and far fewer "that's not what we ordered" disputes at the quay.
Practical tip: Build your recurring stores list once, with IMPA codes attached, and reuse it every voyage. You will cut requisition time dramatically and your suppliers will love you for it.
Want to raise a coded requisition and get quotes from verified suppliers in minutes? Register your vessel on GDS and browse the full IMPA-coded catalogue.
