Walk into any ship's office from Singapore to Rotterdam and you will find the same thick catalogue, or its digital equivalent, sitting next to the requisition forms: the IMPA Marine Stores Guide. For vessel purchasing officers, masters and fleet procurement managers, its six-digit codes are the closest thing the industry has to a universal language. A requisition that reads 'IMPA 170101 x 24 PCS' means exactly the same thing to a chandler in Houston as it does to one in Piraeus, with no translation, no ambiguous product descriptions and no guesswork about what the ship actually wants delivered to the gangway.
This guide explains where the IMPA system came from, how to decode any six-digit number, which sections matter most for day-to-day supply, and how experienced purchasing teams use the codes to cut requisition-to-delivery time and eliminate wrong-item deliveries. If you want to follow along with live examples, every code discussed here can be looked up in the full IMPA catalogue .
What the IMPA Marine Stores Guide Is
IMPA, the International Marine Purchasing Association, was founded in 1978 by a group of senior purchasing executives from shipping companies who faced a common problem: every owner, manager and chandler described stores differently. A 'deck scrubber' on one requisition, a 'hard broom' on another and a 'brush, deck, stiff' on a third might all be the same item, or three different ones. Quotes could not be compared, deliveries frequently missed the mark, and every order required rounds of clarification by telex, fax and later email.
The association's answer was the Marine Stores Guide (MSG): a standardised catalogue that assigns a unique six-digit code to each commonly requisitioned marine store item. Over successive editions the guide has grown to cover roughly 50,000 coded items, spanning everything from provisions and galley utensils to mooring ropes, safety equipment, valves, electrical spares and machinery consumables. Each entry pairs the code with a controlled English description, a standard unit of measure and, in most editions, an illustration, so that the buyer and the supplier are unmistakably talking about the same physical article.
The MSG succeeded because it solved a coordination problem for both sides of the transaction. Ships gained a way to specify exactly what they needed regardless of which port they were calling at next. Chandlers gained a way to price, pick and pack against an unambiguous reference. Within a couple of decades the six-digit code had become the default requisition language of merchant shipping, and today most planned-maintenance and procurement systems store their consumables masters keyed on IMPA numbers.
Anatomy of a 6-Digit IMPA Code
Every IMPA code follows the same simple structure, and once you internalise it you can place any item in the catalogue within seconds:
—First two digits — the section. This is the broad product family: tableware, ropes, paint, safety, tools, valves and so on. The section is the fastest filter when browsing or checking a requisition line.
—Middle two digits — the group. Within a section, the group narrows to a product type: for example, within tableware, cutlery as opposed to glassware or cookware.
—Last two digits — the item detail. The specific article, size or variant within the group.
—17 places the item in Section 17, Tableware & Galley Utensils — everything used to set the mess table and run the galley.
—01 identifies the first group in that section, which covers cutlery.
—01 pins down the specific item: a dinner knife.
So 170101 is a dinner knife, and neighbouring codes run through the rest of the cutlery drawer — forks, spoons, serving pieces — before the section moves on through the other groups of galley equipment. You can browse the whole family under Section 17: Tableware & Galley Utensils .
Two More Examples
IMPA 210101starts with 21, which is Section 21, Rope & Hawsers. The code sits in the opening group of the section, where the natural-fibre cordage entries such as manila rope begin; as the item digits climb, the entries step through the diameters and coil lengths of that rope type before subsequent groups move on to synthetic lines and hawsers. A bosun who knows the section prefix can sanity-check a mooring stores requisition at a glance: anything on the list that does not begin with 21 probably does not belong there. The full range is listed under Section 21: Rope & Hawsers .
IMPA 330101begins with 33, Section 33, Safety Equipment — the life-saving and emergency hardware family. Again the 01-01 suffix marks the first item of the section's first group, and the surrounding codes enumerate the standard life-saving appliances every vessel carries and periodically renews. Because safety items are survey-critical and often certificate-bearing, quoting the exact IMPA number rather than a free-text description is especially important here; see Section 33: Safety Equipment for the section layout.
The Main Sections of the Marine Stores Guide
The MSG is organised into numbered sections, each covering a product family. These are the ones purchasing officers touch most often:
Memorising even half a dozen of these prefixes pays off daily. When a department head hands you a mixed list, the section numbers instantly tell you how the order will split across supplier categories — provisions to one chandler, paints or lubricants possibly to specialist suppliers — and how many delivery lines to plan for the port call.
How Purchasing Officers Use IMPA Codes in RFQs
The code system earns its keep at three points in the procurement cycle.
1. Eliminating Wrong-Item Deliveries
A free-text line like '2 boxes cleaning powder' invites interpretation, and every interpretation the supplier gets wrong costs a re-delivery, a dispute or a crew making do without. An IMPA-coded line removes the interpretation entirely: the chandler picks against the number, and if the wrong article arrives the discrepancy is objectively provable. Crews on tight port stays cannot afford launch runs to return goods, so coded requisitions are the cheapest quality-control measure available to a purchasing department.
2. Comparing Quotes Apples-to-Apples
When three chandlers quote the same coded list, the comparison is a spreadsheet exercise: identical items, identical units, prices side by side. Without codes, each supplier quotes their own interpretation of each line — different brands, pack sizes and grades — and the 'cheapest' quote may simply be quoting a lesser item. Coverage matters too: a disciplined comparison first checks which supplier can actually deliver every line as specified, then compares price on the covered lines, because a low total that silently omits five items is not a low total at all.
3. Multi-Port Sourcing and Fleet Standardisation
Because the code means the same thing everywhere, a fleet purchasing manager can split an order across ports — topping up provisions at the next call and deferring paint to a cheaper port two weeks later — while keeping a single item master. Consumption history keyed on IMPA numbers also becomes comparable across sister vessels, which is the foundation of any serious budget or par-stock exercise. Checking which supply ports sit along a vessel's rotation is easier with a visual overview; a world ports map showing chandler coverage lets you match the requisition split to the schedule in minutes.
Common Mistakes When Working with IMPA Codes
The system is robust, but a few recurring errors still cause friction between ships and suppliers:
—Quoting superseded codes. The MSG is revised periodically; items are added, merged and occasionally renumbered between editions. A requisition built from an old onboard copy or a stale PMS item master may cite codes the supplier's current edition maps differently. Fix: validate codes against a current reference before sending the RFQ, and update the vessel's item master whenever a new edition is adopted fleet-wide.
—Unit-of-measure confusion. Every MSG entry carries a standard unit — piece, set, box, roll, coil, kilogram, litre. Ordering '10' of a rope coded per metre when you meant ten coils, or '5' of an item sold per box of 100 when you needed five pieces, produces deliveries that are wrong by an order of magnitude in either direction. Fix: always state the unit alongside the quantity, and check it against the catalogue entry rather than assuming.
—Mixing IMPA and ISSA numbers. The International Shipsuppliers & Services Association publishes its own catalogue, the ISSA Ship Stores Catalogue, with a separate numbering scheme. Many items exist in both, and experienced chandlers can cross-reference, but pasting ISSA numbers into a column headed 'IMPA' guarantees confusion. Fix: label the numbering system explicitly on every requisition, and standardise the fleet on one primary system.
—Free-text lines buried in coded lists. A requisition that is 90% coded and 10% 'as per attached photo' forces the supplier back into interpretation mode for exactly the lines most likely to go wrong. Where no code exists, give a full controlled description — material, dimensions, standard, unit — rather than shorthand.
How Digital Platforms Change the Workflow
The paper MSG solved the language problem; it never solved the workflow problem. Traditionally, a coded requisition still travelled by email to a handful of chandlers the operator happened to know at that port, quotes came back in incompatible formats, and someone retyped everything into a comparison sheet. The code was standardised — the process around it was not.
Marketplace platforms close that gap by putting the catalogue, the supplier network and the RFQ mechanics in one place. On Geomarine, every code in the guide resolves to its own page — the dinner knife above lives at geomarinehub.com/impa/170101 — where you can confirm the description and unit, then request quotes from verified chandlers at the relevant port directly from the item page. Because the platform covers suppliers at more than 1,200 ports, the same coded requisition can be priced at the current port and the next two on the rotation without rebuilding the list, and the returned quotes arrive line-matched against the same codes, so coverage and price comparison happen automatically instead of in a hand-built spreadsheet.
None of this changes what a good requisition looks like — accurate codes, correct units, realistic lead times. It simply removes the retyping, the format wrangling and the dependence on whichever supplier contacts happen to be in the ship's address book. The officers who benefit most are the ones who already run disciplined, fully coded requisitions: the cleaner the input, the more the matching and comparison work the platform can do for them. Start from the catalogue , search by code or keyword, and build the RFQ from there.
Frequently Asked Questions
How many items are in the IMPA Marine Stores Guide?
Current editions of the guide contain roughly 50,000 coded items across all sections, from provisions to machinery stores. New editions add items and occasionally restructure entries, which is why requisitions should always be checked against a current reference rather than an old onboard copy.
What is the difference between IMPA and ISSA codes?
They are two independent catalogues maintained by two different associations: IMPA (the International Marine Purchasing Association, representing buyers) and ISSA (the International Shipsuppliers & Services Association, representing suppliers). Both assign codes to marine stores and both are widely used; many chandlers work with either. The practical rule is never to mix the two systems in one requisition without labelling which is which.
Do all six digits of an IMPA code matter?
Yes. The first two digits give the section (for example 17 for tableware, 21 for ropes, 33 for safety equipment), the middle two the group within the section, and the last two the specific item or variant. Truncating a code to four digits identifies only a group, not an orderable item — the supplier still has to guess the size or type, which defeats the purpose of coding the line.
Can I order directly using an IMPA code?
The code identifies the item; you still need quantity, unit of measure, delivery port and date to make an orderable line. On a digital marketplace the code does most of the work: looking up a code such as 170101 or 330101 on its item page confirms the specification, and the quote request built from it carries the code through to every supplier, so all returned prices refer to exactly the same article.
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