Walk through any well-run ship's store and you will see the same pattern: crates labelled with five or six-digit numbers, inventory sheets organised by the same numbers, purchase orders that reference those same numbers. These are IMPA codes - and their cousins, ISSA codes. To anyone new to marine procurement, they look like a bureaucratic mystery. They are not. They are the most efficient piece of vocabulary in the entire industry.
Here is the simple version. IMPA stands for the International Marine Purchasing Association. The IMPA Marine Stores Guide is essentially a global product catalog that assigns a unique code to tens of thousands of items a vessel might need - from a specific grade of cotton waste to a class-approved emergency torch. ISSA, the International Ship Suppliers Association, maintains a parallel classification. Most items have equivalents in both systems. A requisition using IMPA codes is understood identically by a chandler in Chennai, Rotterdam, or Singapore.
Why codes beat descriptions
A vessel's chief officer writes "heavy duty mooring rope, 22mm." In free text, this is ambiguous. 22 mm what - polypropylene, polyester, HMPE, mixed? What breaking load? What length? What certification? Now imagine the same item referenced as IMPA 23 01 04 (an example format). The chandler looks at the code, the spec is fixed, the price is comparable, and the delivered item is exactly what the vessel expected.
We quote requisitions that use IMPA codes significantly faster than free-text ones, often by a factor of three. There is simply less back-and-forth. When a ship's purchaser is chasing a 2-hour quote turnaround for a Chennai call, that speed multiplies through the entire chain.
How the coding is organised
IMPA codes group items into categories - for example, rope and wire rope live in one chapter, safety equipment in another, cleaning chemicals in a third. Within each category, codes get progressively more specific. This means a purchaser can browse an entire category before narrowing to the exact spec, which is useful when they know what function they need but not the precise specification.
ISSA follows a similar logic with some different groupings - galley items are organised slightly differently, and ISSA's classification of bonded stores is somewhat more granular. Experienced purchasers often keep both guides on the bridge and reference whichever is better organised for the category.
Where codes fall short
Not every item has a code. New technology - methanol-compatible cleaning agents, lithium-ion battery handling equipment, certain newer ammonia detectors - often lands in the market before the code lists catch up. For these, we work from manufacturer part numbers, ISO specifications, or class-society approval numbers. A good chandler knows when to use the code and when to drop to the underlying spec.
Codes also cannot substitute for quality control. Two IMPA 77-series filters can look identical on paper; only one may actually be OEM-grade. This is where the sourcing relationship matters - the code tells you the shape of the item; the supplier relationship tells you whether it will last the service interval.
Practical advice for vessel purchasers
Keep both IMPA and ISSA guides updated annually. The codes evolve - items get retired, new items get added, category numbering occasionally shifts. Build your standing requisitions around codes rather than descriptions. For genuinely unusual items, keep a parallel note of the manufacturer part number alongside the code. And train new crew on the code structure before their first procurement cycle; a two-hour induction saves weeks of back-and-forth on first-month orders.
For chandlers supplying vessels across Chennai, Ennore, and Kattupalli, IMPA and ISSA coding is the common language that makes multi-supplier procurement work. Without it, every requisition would be a translation exercise.
Need a supply partner who processes IMPA and ISSA requisitions as a default? See our ship chandler at Chennai Port capability overview.