A refractory Certificate of Analysis (COA) is useful only when it can be tied to the material being supplied and to the acceptance rules in the purchase order. A polished document is not evidence by itself. The reviewer needs to connect the product grade, batch or lot, sample, test method, specimen condition, units, result and contractual limit.
This guide does not publish universal tolerances. Refractory acceptance limits vary by material family, grade, application, project specification and test procedure. The practical question is therefore not “does this number look normal?” but “was the agreed property tested on the right sample, by the agreed method, under the agreed conditions, and does the result meet the stated criterion?”
Step 1: Confirm the Document and Batch Identity
The seven fields that make a result reviewable
PRODUCT / GRADE: exact ordered designation LOT / BATCH: identifier matching bags, pallets or labels SAMPLE: source, location, quantity and sampling date PROPERTY: chemical or physical characteristic required METHOD: standard number, edition and any agreed deviation CONDITION: specimen preparation, curing/drying/firing and units RESULT / LIMIT: measured value beside the contractual acceptance rule
A COA may contain additional fields such as production date, test date, laboratory, report number and approval signature. Those fields support document control, but they do not cure a missing batch link or an undefined test condition.
Step 2: Match Each Property to the Purchase Requirement
Chemical composition can help confirm material identity and grade, but no single oxide percentage proves service performance. The relevant oxides and reporting limits must come from the ordered grade, applicable material standard and project specification.
| Property group | Document check | Common comparison error |
|---|---|---|
| Chemical composition | Method, basis of reporting, units and required oxides | Comparing a typical datasheet value with a contractual limit |
| Bulk density / porosity | Material form, test method and specimen condition | Comparing burned brick data with a castable test piece |
| CCS / MOR | Specimen geometry, preparation, conditioning temperature and units | Comparing results taken after different heat treatments |
| Permanent linear change | Reference length, firing temperature, hold time and sign convention | Reading expansion and shrinkage without the test schedule |
Do not invent a tolerance during document review. If the purchase specification gives no limit for a reported property, record it as information only and ask the purchaser or designer whether an acceptance criterion is required.
Step 3: Check the Test Method and Specimen Condition
ASTM and ISO documents answer different questions. A classification standard is not automatically the test method for every property, and a method written for burned brick should not be assigned to an unshaped castable without a valid basis.
| Reference | What its published scope covers | How to use it in review |
|---|---|---|
| ASTM C401-12(2022) | Classification of alumina and alumina-silicate castable refractories | Confirm that a claimed castable class follows the referenced classification; do not treat it as the method for every reported property |
| ASTM C133-97(2021), historical | Cold crushing strength and modulus of rupture of refractories | If a contract cites it, confirm that the named edition remains the agreed basis; check specimen and loading conditions before comparing results |
| ASTM C20-00(2022) | Apparent porosity, water absorption, apparent specific gravity and bulk density of burned refractory brick and shapes by boiling water | Confirm that the material form and method match; do not apply a burned-shape result to monolithic material by assumption |
| ISO 1927-5 | Preparation and treatment of test pieces for unshaped refractory products | Use with the agreed test programme to check mixing, shaping, curing, drying and firing records |
| ISO 1927-6:2012 | Measurement of physical properties of unshaped refractory products | Confirm the reported property and the test-piece preparation reference are paired correctly |
Always verify the edition required by the tender or purchase order. A later edition is not automatically interchangeable when the contract names a specific edition.
Minimum condition data for physical properties
- Material form: burned brick, prefabricated shape, dry mix, cast or gunned monolithic.
- Sampling source and relationship to the supplied lot.
- Specimen dimensions and preparation method.
- Water addition or mixing condition where relevant.
- Curing, drying and firing temperature, duration and sequence.
- Number of specimens and whether the result is individual, average, minimum or maximum.
- Units and rounding convention.
Quality Red Flags in COA Documents
Step 4: Hold, Clarify, and Retest Without Losing Traceability
1. Quarantine the affected lot
When a required result is missing, outside the agreed limit or not traceable to the shipment, identify and hold the affected material according to the receiving-inspection procedure. Do not mix it with released stock while the document issue is unresolved.
2. Issue a specific clarification request
State the document number, lot, property, reported value, required limit and missing method or condition. Avoid vague requests such as “send a better COA.” A reviewable response should resolve the exact gap.
3. Preserve the document chain
Keep the original file, revision, sender, receipt date and any superseding report. A replacement COA should identify what changed and remain tied to the same lot or to a clearly documented resample.
4. Use agreed sampling and retest rules
Independent testing may be appropriate for critical service, disputed results or contractually defined surveillance. The inspection and test plan should specify who samples, where the sample is taken, sealing and chain of custody, laboratory qualification, method and edition, acceptance rule, retest procedure and allocation of cost.
5. Record the disposition
The final status should be explicit: released, conditionally accepted by authorized personnel, reworked, replaced or rejected. A technical explanation does not itself authorize use of nonconforming material.
Document-control evidence to retain
Depending on the project and contract, the file may include:
- Purchase order, approved datasheet and applicable specification revision.
- Supplier COA or batch test report and any revisions.
- Material labels, packing list and receiving photographs.
- Sampling record, seal numbers and chain-of-custody record where used.
- Independent laboratory report and purchaser disposition.
Need COA Interpretation Support?
Send the purchase specification together with the sample COA. We can first identify missing fields and comparison gaps; material acceptance and third-party testing remain project-specific.
Step 5: Put the Document Rules in the RFQ and PO
A supplier cannot reliably prepare the required document pack if the tender only says “COA required.” Define the minimum fields, submission timing and disposition process before award.
COA / BATCH TEST REPORT CHECKLIST [ ] Exact product and grade designation [ ] Purchase order item and quantity covered [ ] Lot / batch number matching material markings [ ] Sampling basis and sample identification [ ] Required properties and actual measured results [ ] Contractual acceptance limit beside each result [ ] Test method, edition, units and specimen condition [ ] Curing / drying / firing schedule where relevant [ ] Test date, report number and laboratory identity [ ] Authorized approval or controlled electronic issue [ ] Rule for missing data, nonconformance and retest [ ] Required submission point: bid, approval, pre-shipment or delivery
Do not copy this checklist as a technical specification without engineering review. The purchaser must add the correct property list, limits, methods, sampling frequency and test-piece conditions for the actual refractory grade and service.
Official Standards References
- ASTM C401-12(2022) — classification of alumina and alumina-silicate castable refractories.
- ASTM C133-97(2021) — ASTM currently lists this cold crushing strength and modulus of rupture reference as historical; confirm the contractual basis before use.
- ASTM C20-00(2022) — apparent porosity, water absorption, apparent specific gravity and bulk density of burned refractory brick and shapes by boiling water.
- ISO 1927-5:2012 — preparation and treatment of test pieces for unshaped refractory products.
- ISO 1927-6:2012 — measurement of physical properties of unshaped refractory products.
These links identify the published scope of each reference. The full standard, contract and project specification control the detailed procedure and acceptance decision.
The decision rule
Release a refractory lot only when the material identity, required document, sample, method, specimen condition, units, result and acceptance criterion form one traceable chain. If one link is missing, record the gap and resolve it before treating the COA as proof of compliance.
Technical scope: document review and procurement workflow. This guide does not establish product-specific acceptance limits, certify any batch, or replace the applicable standard, project specification, inspection plan or laboratory report.