A third-party inspection (TPI) certificate is a document issued by an independent inspection body. It states that specific goods were inspected or tests were witnessed against a stated specification, and records the result.
TPI certificates are common for valves, pipes, fittings, castings, forgings and pressure equipment. Many oil, gas, water and infrastructure projects will not accept goods without one.
What a good certificate contains
- The name of the inspection body, the inspector and the issuing office.
- The buyer's purchase order number and the supplier's invoice or packing list number.
- A clear description of the goods, with quantities, sizes, heat numbers or serial numbers.
- The standards and specifications inspected against, with their revision.
- The scope: which checks were done, which tests were witnessed, and which documents were reviewed.
- The result, the date and place of inspection, and a signature or stamp.
Read the scope, not just the stamp
The most common problem is a certificate with a narrow scope. An inspector who only checked quantity and marking can still issue a certificate that looks official. It says nothing about dimensions, material or pressure tests.
So write the scope into your purchase order. List the tests to be witnessed, such as hydrostatic shell and seat tests for valves, and the documents to be reviewed, such as EN 10204 material certificates. Ask for the inspection and test plan to be agreed before production.
Also check that the certificate's heat and serial numbers match the goods and the material certificates. A certificate that covers a different batch is useless.
Ask for the inspector's stamp or a tag on the goods themselves, where your specification allows it. Some inspection bodies stamp valves or forgings after witnessing tests. That links the certificate to the physical item your customer receives.
TPI and other certificates
A TPI certificate is not a product certification such as CE marking or UL listing. It confirms an inspection of one consignment. It does not certify a design or a factory.
It also does not move legal responsibility for quality. The supplier still owes you goods that meet the contract, even after a certificate is issued. Keep that point clear in your contract, so a signed certificate cannot be used to reject a later claim.
Some project specifications use their own terms, such as "inspection release note" or "release certificate". The principle is the same. Before production, get your customer's exact document requirement in writing and pass it to the supplier and the inspection body.
Your customer may name the inspection agencies it accepts. Our guide to third-party inspectors in Gujarat explains how to choose when it does not.
Next step
We check documents and inspect goods for you, and we can coordinate a TPI agency to your scope. To set up inspection for your order, book a free sourcing review.