API 594 Inspection & Test Plan (ITP)
A typical stage-wise ITP / quality plan for valves supplied to API 594 — inspection activities, tests, acceptance references and verifying documents, with recommended hold, witness and review points for QC and third-party inspection.
What is the ITP for API 594 valves?
An Inspection & Test Plan (ITP) sequences every check between raw material and dispatch, and assigns each an inspection level — Review (document check), Witness (inspector may attend), or Hold (work stops until released). The plan below is a typical ITP for valves built to API 594 (Check Valves: Flanged, Lug, Wafer, and Butt-Welding); the tests and documents are drawn directly from the standard's requirements. Use it to structure your QAP or coordinate third-party inspection.
1. Documentation & design review
Review- Approval of drawings, datasheets and QAP against API 594
- Face-to-face and end-to-end dimensions per API 594 tables (Type A wafer; Type B lug; Type C flanged)
- Minimum plate/disc thickness and spring material specification
2. Raw material verification
Review- Material Test Reports (MTRs) review per EN 10204 3.1/3.2
- Positive Material Identification (PMI) of pressure-containing parts
3. Dimensional inspection
Witness- Dimensional check per API 594 / ASME B16.34 / applicable face-to-face
- Wall thickness verification
4. NDE (as applicable)
Witness- Visual, and RT/UT/MPI/DPT of castings/welds per specification
5. Pressure & performance testing
Hold- Shell test: 1.5× rated pressure
- Seat leakage test: 1.1× rated pressure per API 598
- Low-pressure seat test: 6 bar air
Primary hold point — witnessed shell, seat and backseat tests.
6. Marking, painting & preservation
Review- Nameplate & body marking verification
- Painting/coating DFT check, end protection and preservation
7. Final documentation
Hold- API 594 compliance certificate
- Material Test Reports (MTR)
- Pressure test certificate
Final documentation review before release/dispatch.
This is a typical ITP framework populated from API 594 requirements, for reference. The actual hold/witness/review split is agreed per project between purchaser, manufacturer and the third-party inspection agency in the approved QAP. Confirm project-specific requirements before use.
Need API 594 valves with a full ITP?
We supply API 594-compliant valves with a project-specific ITP, in-house QC and third-party inspection (SGS, BV, TUV, DNV) coordination — hold and witness points accommodated. Get a 24-hour quote.