Steel Coil · Standard JIS G 3302
JIS G 3302 Galvanized Coil — the Standard Number Tells You Less Than the Order Does
This is the Japanese standard for hot-dip zinc-coated steel sheet and strip, and the coil form is the one most enquiries are actually about. What a JIS number does not do is tell you which published edition your project is bound to, how much zinc the coating is meant to carry, what the surface has to look like, or which acceptance tests the consignment will be judged on. Those are order fields. This page is built to settle them before the enquiry goes out.
Before you ask for a price
- The standard covers both coil and sheet — the form you buy is an order condition, not a separate standard.
- Which edition governs is confirmed against the publisher, not assumed from the newest text.
- Coating class, surface and acceptance tests are stated explicitly — never inherited from the JIS number.
Publication status checked against the JSA catalogue as of
Buyer Fit
You are buying a coated product, and the standard is only its frame
A JIS G 3302 enquiry usually arrives with the number already fixed — because the project specification names it, or because a previous package used it. That is a reasonable starting point and a poor finishing point. What the number establishes is which document family governs; what the order still has to establish is everything the coating will be measured on.
Continuously hot-dip zinc-coated coil begins as cold rolled or hot rolled substrate and acquires a zinc coating on a continuous line. The moment the coating is applied, the thing being bought changes character. It is no longer defined by the steel underneath it alone; it is defined by what is on the surface, how much of it there is, and what the surface is expected to look like. Those are coating fields, and they live in the standard rather than in a product list.
That is why a JIS G 3302 galvanized coil enquiry cannot be closed by confirming the standard applies. The standard sets out the products, the coating classes it recognises and the basis on which the coating is demonstrated. It is a framework within which a number of distinct products exist, and picking one of them is the buyer's act. A quote that names the standard and a thickness has named the frame and left the content open.
There is a second layer to this that is easy to miss, and it is the one that costs money when it is missed. The standard is maintained, and maintained documents are revised. A project specification written eighteen months ago may cite an edition that has since been superseded, or — more awkwardly — may cite the standard with no edition at all. Neither situation is unusual, and both produce the same failure: two parties believing they have agreed one requirement while reading two different texts. Settling the edition is a reading from the publisher rather than an inference from what the trade is saying about the standard.
Coil and sheet under one standard
The standard addresses the coated flat product, and coil and sheet are two forms of it rather than two standards. That is convenient for a project that needs both, and it is a trap for an order that does not say which one it is buying. Coil arrives as a wound, banded unit destined for a decoiler or a levelling line; sheet arrives as flat cut lengths. The coating requirement travels across both, but the geometries, the edge conditions and the protection for transit do not. If your scope includes both forms, they need stating separately — the same standard number covers either.
This standard is the right frame if…
- The coil is continuously hot-dip zinc coated. The coating is applied by passing the strip through molten zinc on a continuous line, which is the process this standard family is written around.
- You are buying the coated product as delivered. The coil is supplied coated rather than as bare steel to be protected downstream, so the coating requirement is part of what you are purchasing.
- The form is coil or strip, or coil and sheet together. Both forms sit inside the same document, so a scope that includes cut lengths as well does not send you to a second standard.
- A Japanese-governed specification is what you are bound to. The project, client or contract has adopted the JIS system for this product, so the citation is one you have to order against rather than compare.
Move to a different route if…
- The material is uncoated and the surface is the steel itself, so a different document governs. See the steel coil range
- You are still deciding which system's standard governs the product at all. Start from the coil standards index
- The coating is a European one your project cites by its own designation. The European coating route
- You need the coated product supplied as flat cut lengths rather than coil. See the steel sheet range
Applicability Check
Six fields a JIS G 3302 enquiry has to declare
Describe the enquiry as you would issue it. The check reports what the description carries, where it is silent, and whether the edition question — and the publication status behind it — has actually been answered. It states no coating mass figure, no class value and no edition year.
Describe the enquiry as it stands today
Answer the six fields below. The check separates the fields that define the coated product from the ones that only supply it, and treats the edition question as its own finding.
This reviews an enquiry, not a product. It states no coating mass figure, no coating class value, no edition year and no test value, and it makes no judgement about whether a coating suits an environment.
Applicability findings
Answer the six fields above. The review reports which define the coated product, which only supply it, and whether the edition and its published status have actually been established.
Nothing here is a specification against a standard, and nothing here states which edition is current. It is a check that the enquiry identifies a coated product rather than describing one.
Why the number alone does not fix the edition
A standard's number is stable; its content is not. Where a standard is maintained, the number carries on while the text behind it changes. So an enquiry citing the standard without a date is consistent with more than one document, and the parties may each believe they have agreed the same requirement when they have not. On a coated product that gap is expensive, because the disputed field is usually the coating amount or the surface condition — measured characteristics that either meet a stated figure or do not. The way to close it is procedural rather than technical: cite the edition your contract invokes, and read the publisher's own catalogue to establish which text that is and whether it is current. Trade discussion, a supplier's product list and a draft circulating for comment are all useful signals, and none of them is the standard.
Where It Stops
Four things a JIS number is often read as saying, and does not
Each of these is a shortcut taken when a coated product is specified from a description rather than from the standard. Each one moves a decision onto whoever quotes that belongs to the buyer — and each one is invisible until something is rejected.
The coating is left at the mill's standard product
An enquiry that names the standard, a substrate and a thickness has specified a kind of coating rather than an amount of it. Two coils can be coated on the same line at different coating masses, both conforming to the standard, and both describing themselves as the product you asked for.
Boundary: the coating class is a stated requirement. Put it on the enquiry, or accept whichever figure is applied.
A newer edition is assumed to apply automatically
Publication of a revised text does not by itself move an existing contract onto it. The edition governs because the contract invokes it. Assuming the most recent text applies is a decision taken silently, and it is the buyer who carries it.
Boundary: check what your contract cites, and confirm the edition's current publication status with the publisher rather than assuming.
The substrate is treated as the specification
Coated coil gets quoted from a substrate-first product list, which makes the underlying steel feel like the substance of the order. It is not. Once coated, the coating class, the coating mass and the surface condition carry the performance the buyer is paying for.
Boundary: specify the coated product as a coated product. The substrate is one field among several, not the specification.
Appearance is assumed to follow from conformance
Conformance establishes that the coating meets the standard's requirements. It does not establish that the visible surface matches an architect's or a client's expectation. Those are different requirements, and only one of them appears on a mill certificate.
Boundary: if appearance is judged at handover, write it into the order. It will not arrive by implication.
The pattern is the same across all four: a coated coil is being treated as its substrate with something added, so the fields that actually define it are left implicit. The remedy is to write the enquiry as a coated enquiry — form, coating class, surface condition and acceptance basis stated, and the edition named and its status confirmed — and let whoever quotes confirm rather than interpret.
Order Conditions
What a JIS G 3302 coil order has to carry
A coated product is defined by fields that do not exist on an uncoated order. These are the ones the mill works to — anything absent is decided by whoever quotes, and anything absent is also absent from the basis your inspection will use.
| Order field | What it decides |
|---|---|
| The form being supplied | Coil, strip or flat cut lengths. Both forms sit inside the standard, so the number does not select one — and the geometry, edge condition and transit protection differ between them. |
| The edition the contract invokes | Which text the coating class, the surface condition and the acceptance basis are measured against. Without it the same words can describe two different products. |
| Coating class and specified coating mass | Which coating the product carries and how much of it per unit area. This is the field that defines the coated product; without it the enquiry names a process rather than a product. |
| Substrate material and grade | The steel beneath the coating, which governs formability and is required alongside the coating rather than instead of it. |
| Thickness and width, with tolerances | The delivered size band inspection accepts against. The coating sits on top of the ordered thickness rather than inside it, so the two must be stated separately. |
| Surface condition and treatment | What the visible surface is expected to be — including any treatment such as a surface passivation or oiling — and what the client inspects at handover. |
| Coil geometry, mass and quantity | Whether the coil suits your decoiler or levelling line: inner diameter, outer diameter, coil mass range and the number of units or total tonnage. |
| Acceptance tests, documents and destination | What is demonstrated at acceptance, against which basis, and the protection and document set the receiving end expects — including the destination for shipment planning. |
Related routes on this path
Releasing galvanized coil at goods-in
- Confirm the certificate cites the standard with the same edition your contract invoked, not the number alone.
- Check the coating class or coating mass recorded against the figure your order stated — not against a generic product description.
- Verify the surface condition recorded matches what the finished work will be judged on, particularly where appearance matters.
- Compare thickness against the specified figure, remembering the coating sits on top of the ordered steel thickness rather than inside it.
- Record the coil's handling, banding and wrapping on arrival, since coating and edge damage in transit shows up later as corrosion and is hard to attribute once the coil has been unbanded.
Why the acceptance basis is worth writing down
A galvanized coil can conform on every measurement and still be rejected in service, because the requirement it was bought against was never stated. Fixing the coating class, the surface condition and the acceptance basis at enquiry stage costs one exchange. Fixing them after finished panels have been fixed to a building costs a commercial conversation in which nobody can point to what was agreed.
What each document actually verifies, and who holds it
A certificate is only as useful as the requirement it is read against. These are the records a coated coil consignment normally travels with, what each one demonstrates, and the action that closes it at enquiry stage.
| Evidence / document | What it actually verifies | Who normally holds it | Enquiry action |
|---|---|---|---|
| Mill test certificate for the heat or lot | The material in the lot it was tested from, in the terms the edition your order names requires. | The delivering mill | Name the document and edition the certificate is to be read against. |
| Coating mass / coating class result | That the coating on the delivered coil meets the class or figure your order stated — the measurement that defines the coated product. | The mill or the coating line | State the required coating class on the order, not after delivery. |
| Coating adhesion and surface inspection record | That the coating is soundly bonded and the surface meets the condition written into the order. | The mill, or your receiving inspection | Agree which checks your goods-in performs and against which requirements. |
| Conformity / inspection document for the consignment | That the delivered lot is declared against the requirement set by the document named on the order. | The mill or the delivering party | State the content requirement with the order rather than after dispatch. |
| Dimensional verification record | The thickness and width check at goods-in, remembering the coating is additional to the ordered thickness. | Your project's receiving inspection | Fix who checks it and against which document before delivery. |
| Packing, protection and shipping documents | That the coil was protected for the route it travelled and that the consignment documents match the order for the destination. | The mill and the shipping party | State transit protection and the document set with the order. |
GCC Supply
Galvanized coil into Gulf environments
Coated product is bought for what the coating does, so the destination is part of the specification rather than a delivery detail. Coastal humidity, salt exposure and site storage all bear on whether the coating specified will still be performing when the client inspects.
United Arab Emirates
Local and re-export enquiries where the coating class and the contract edition are settled together before the coil is committed.
Steel coil supply for United Arab Emirates
Saudi Arabia
Programme volumes for cladding and building envelope work, where the coating is chosen against the exposure the finished panels will see.
Steel coil supply for Saudi Arabia
Qatar
Project supply with a technical submittal, so the coating class and the edition have to be on the record before material is released.
Steel coil supply for Qatar
Oman
Port-oriented routes where coastal exposure makes the coating the decisive field and transit protection part of the specification.
Steel coil supply for Oman
Bahrain
Industrial supply where the document set carries weight, because the coating is demonstrated by certificate as much as by inspection on arrival.
Steel coil supply for Bahrain
Kuwait
Manufacturing supply where the galvanized coil feeds a profiling or pressing line, so coating and forming duty are fixed before the run.
Steel coil supply for KuwaitThese pages set out the enquiry handling for each destination. They do not claim local warehousing, stockholding, a branch presence or a delivery timescale — those are confirmed against your own order. Where a galvanized coil is destined for a corrosive site environment, state the exposure the finished component will see: the coating class is chosen against that exposure, and a class picked from a generic product list without reference to it is a decision made by nobody.
Reference Notes
Reading this standard, and the limits of what this page will state
A coating standard does several jobs at once: it designates the product, fixes the coating classes it covers, and sets the basis on which the coating is demonstrated. That is why the edition — and the publisher's current status for it — is not a formality.
A coating standard defines a product family, not a single product
The standard sets out the coated products it covers, how the coating is designated, the conditions they may be supplied in and the basis on which the coating is demonstrated. It is a framework within which many distinct products exist. Choosing one of those products — a specific coating class, a specific surface and a specific condition — is the buyer's act, and the framework does not do it for them.
Edition and product selection are different decisions
The edition decides which text you are working to. The selection decides which product within that text you are ordering. Both have to be settled, and settling one does not settle the other — a buyer who fixes the edition but leaves the coating class open has done half the work, and the less visible half.
Publication status is a publisher's fact, not a trade signal
Coating standards are maintained, and the work is often discussed well before it concludes. Discussion, a draft circulating for comment and a published edition are three different states. For an order, only the third matters — and establishing which is a reading from the publisher's catalogue rather than an inference from what the trade is saying.
The certificate demonstrates the coating, and only the coating
A certificate shows that the coated product met the stated requirements on the stated basis. It says nothing about whether those requirements suit the environment the finished component is going into, and nothing about appearance beyond what was written into the order. Reading it as broader assurance than that is the most common misreading on coated supply.
This page states no coating mass figure, no coating class value, no composition, no thickness range and no test value, and it makes no claim today about which edition is published or whether a revision has been issued. Coating standards are maintained, and both the content and the publication status change — so the publisher's own catalogue is the only source that stays accurate. Read the edition your contract invokes, and confirm its status there before applying it to an order.
Which field answers which question
Form and the contract edition
Whether you are buying coil or sheet, and which text the coating is measured against.
Coating class and coating mass
Which coated product this is — the field that defines what is on the steel and how much.
Substrate and dimensions
What the steel underneath is, and the delivered size band inspection works to.
Surface condition and treatment
What the visible surface should be, and any treatment the coil is supplied with.
Acceptance tests, documents and destination
What is demonstrated at acceptance, and what protection the route in requires.
Where It Is Applied
Six situations where the enquiry, not the standard, decides the outcome
These are the settings in which a galvanized coil enquiry most often goes out with the standard fixed and the product still open. The coating requirement becomes concrete in each of them, and in each of them the same two fields — coating class and surface condition — are the ones that go missing.
A building envelope specification names the standard
The specification says the cladding is to be galvanized and cites the standard, stopping short of the coating class. The durability requirement is expressed as a material rather than a quantity, and the coating amount is left to whoever quotes.
Coil is bought for a profiling line feeding a project
The coil is ordered before the erection programme is fixed, so the coating and the forming duty both have to be settled on the strength of the project documents rather than on site conditions that will only appear later.
A project specification references an older edition
The specification was written against the text in force at design stage. The question is whether that edition still governs, and whether it is still the current published text — two different questions with two different answers.
Galvanized and uncoated items sit on one purchase order
One order covers both coated and bare components. The coated line items need their own declaration — form, coating class and surface — because the uncoated fields do not describe them.
A client rejects finished panels on appearance
The coating conformed to the standard and the panels still did not match, because the surface condition was never written into the order and conformance does not, by itself, carry an appearance expectation.
Coil is held between phases of a project
Material bought for one phase is carried into the next. Someone has to confirm that the coating class and the recorded edition still suit the second use, and that the storage between phases did not compromise the coating.
Where the coating is being chosen for what the finished building element has to withstand, the requirement comes from the exposure rather than from a product list. If the material will be supplied as flat product cut to length rather than as coil to feed a line, the dimensional and handling questions change even though the coating requirement does not — the steel sheet range covers that form.
The decisions that sit either side of this standard
DX51D galvanized steel coil
The general-purpose coated grade most commonly quoted with a coated coil enquiry, where the coating requirement is stated alongside the grade rather than instead of it.
Open the grade pageSteel coil thickness chart
Confirm the nominal thickness basis your enquiry is written on before the coating is specified on top of it, since the coating sits outside the ordered thickness.
Open the thickness referenceFAQ
What a JIS buyer asks before placing a coated coil order
Written around the questions that decide whether the JIS citation is actually applicable to the coil in front of you.
Does JIS G 3302 cover coil, or only sheet?
The standard is written for hot-dip zinc-coated steel sheet and strip, and the two forms are addressed within the one document rather than under separate numbers. That matters practically because coil and cut sheet carry different handling, edge and packaging conditions even though the coating requirement is the same. State the form you are buying as an order condition — the standard number alone does not select it for you.
Which edition of the standard should my order cite?
The one your contract invokes, not whichever text happens to be newest. A standard number is stable while the text behind it is revised, so a citation without a date is consistent with more than one document and the parties can each believe they have agreed the same requirement. Read what your purchase order or project specification actually cites, and confirm that edition's current publication status with the publisher before you order against it.
Does the JIS number tell me how much zinc is on the coil?
No. The amount of coating is a measured requirement that has to be expressed in the order as a coating class or a specified coating mass per unit area in the terms the standard uses. Two coils can be supplied from the same substrate, coated in the same bath, and carry different coating masses while each is described as the product you asked for. The coating class is the field that closes that gap.
What acceptance tests should the enquiry require?
The ones your project's inspection will actually use. Coated products are demonstrated by a combination of coating-mass, adhesion and appearance-related checks, and which of those the client's receiving inspection performs is a project decision rather than something the standard number implies. Fix the test basis and the certificate type at enquiry stage, so the documents that arrive at dispatch are evidence against the same basis your inspection applies.
Can I treat a JIS coating class as equivalent to a European or ASTM one?
Not by the designation. Each standard family defines its own classes, its own coating designations and its own test regime, so two labels that look comparable are not a shared designation — the documents behind them are different documents. If your project has adopted a particular standard, the coating should be reviewed against that standard's own text and edition rather than cross-matched on a label. Substitution on resemblance is a decision neither document supports, and it cannot be settled from a web page.
The coil is definitely galvanized — why ask about the coating at all?
Because galvanized describes a process, not a quantity or a class. What gets checked at acceptance is a measured figure against a stated requirement, and what the finished component has to survive is an exposure. If neither the coating class nor the exposure is written down, the requirement that will actually be judged has never been stated, and the certificate that arrives demonstrates whatever basis the mill applied rather than the one your project assumed.
Request a Quote
Send the form you are buying, the edition your contract invokes and its confirmed publication status, the coating class or specified coating mass, the substrate and grade, the thickness and width with tolerances, the surface condition and any treatment required, the coil geometry, mass and quantity, the acceptance tests and documents the project calls for, and your destination. Price is on request.
Galvanized coil enquiries on this route are handled through the steel coil desk — the main steel coil enquiry desk. The form here reaches the same team.
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