Heat-number traceability from the MTC to the body
On a typical steel valve, the foundry or forge marks a heat (melt) number on the body. That number should appear on the material test certificate, together with the specified grade (for example ASTM A216 WCB) and the chemical and mechanical results for that heat. The inspector checks three things that often come apart in practice:
- The heat number cast, stamped or etched on the body is legible (see also MSS SP-25 vs EN 19).
- A 3.1 (or 3.2, if specified) certificate for that exact heat is on site, or is submitted before release.
- The grade, heat treatment and any supplementary requirements on the certificate match the purchase order.
In the sample report the body mark H2611-07 was present, but the certificate for that heat was not. The marking section can still be “OK (MTC pending)” while the documents section is PENDING. That is deliberate: the inspector reports what was seen, and does not convert a missing certificate into a silent pass.
When a 3.2 certificate is actually required
Type 3.2 is a 3.1-style inspection certificate that has also been validated by an inspector designated in official regulations or named by the purchaser — typically a purchaser’s inspector or an independent inspection body attending the material tests or reviewing them under agreed procedures.
It is required when the contract, the end-user specification, or the applicable regulation says so. It is not the default for every industrial valve, and it is not created by stamping “3.2” on a 3.1 form after the fact. Some pressure-equipment or energy projects require 3.2 for pressure-containing parts; many commercial valve orders are written for 3.1 only. If you need 3.2, say so in the PO before the foundry pours the heat, because the independent witness has to be arranged around the tests.
ValveWitness can, when instructed, review the certificates presented at the factory and, where the scope includes it, check that heat marks match those certificates. A 3.2 validation of mill tests is a separate appointment at the mill or foundry, agreed in advance. We do not issue material certificates of our own.
