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A valve is a pressure boundary, and a single porous casting or a mismatched seat can become a leak, a shutdown or a safety incident. That is why serious buyers either attend a Factory Acceptance Test (FAT) or commission a Third-Party Inspection (TPI) before the container leaves the plant. This checklist walks through what a disciplined pre-shipment inspection actually covers – from raw material to packaging – and the defect patterns that most often cause rejection.
Inspection is layered, cheapest defect caught earliest: raw material → in-process machining → finished-product performance → final acceptance & packaging. Catching a wrong alloy at the spectrometer stage costs nothing; catching it after hydrostatic test and painting costs a rebuild. Build the inspection plan into the purchase order, not the complaint afterwards.
Measure against the governing standard – ASME B16.10 / ISO 5752 for face-to-face, ASME B16.5 / GB/T 9112 for flange drilling (bolt circle, hole diameter, count), and verify minimum wall thickness and minimum bore. For import projects, confirm the structure length matches the pipeline drawing – a few millimetres of mismatch means the valve will not seat between the flanges. Sample critical dimensions on every valve for small batches; for large orders use a documented sampling plan.
Request the Mill Test Report (MTR) to EN 10204 3.1 for every pressure-containing part and verify the heat / furnace number is traceable to the casting. For alloy and stainless valves, require PMI (Positive Material Identification) – a portable spectrometer check of the actual body chemistry, because substituted bolts or castings are a leading rejection cause. In sour (H₂S) service, the material must additionally meet NACE MR0175 / ISO 15156.
Per API 598 / ISO 5208 / EN 12266, two tests are mandatory and run in order – shell first, then seat:
Soft (resilient) seats must be bubble-tight; metal seats are permitted limited leakage per the standard. Gate and ball valves have two seat pairs and need a bi-directional seat test. Always witness or record the test – a passing test report with no valve ID attached is worthless.
Check the blast grade (typically Sa 2.5), dry-film thickness with a gauge (per the spec, e.g. 150–250 µm for epoxide), and adhesion by cross-cut (peel area ≤ 5% after tape pull). For coastal or corrosive sites, confirm the topcoat system and salt-spray rating. Peeling paint at the destination is the most visible – and most avoidable – quality complaint.
Operate the valve through its full stroke: it must move smoothly with no bind, and the measured operating torque must match the design / actuator rating. For actuated valves, close using the actuator itself and confirm limit-switch feedback. Note the Cv or flow-direction consistency where the spec requires it.
Flange faces and threaded ends must be capped; the internal bore clean and dry (residual test water can rust a valve in transit). Correct transport position: gate / globe / butterfly / diaphragm – fully closed (diaphragm not over-tight); ball / plug – fully open; check-valve disc – closed and fixed (remove the fix before testing). Wooden crates or cartons must protect against handling shock.
Two mandatory tests per API 598 / ISO 5208 / EN 12266: a hydrostatic shell test at about 1.5x the rated pressure (no visible leakage, hold 2-10 min) and a seat-leak test at about 1.1x rated pressure. Soft (resilient) seats must be bubble-tight; metal seats are allowed limited leakage per the standard. A low-pressure air test is added for soft-seated and gas-service valves to catch micro-leaks.
At minimum: Mill Test Report (MTR) to EN 10204 3.1 for pressure-containing parts, the factory test report (shell + seat pressures, durations, results), the Inspection Report (IR), material certificates, NDE reports where specified, and the Certificate of Conformity. For API-tagged valves also request the monogram license number and verify it on the API directory.
Gate, globe, throttle, butterfly and diaphragm valves ship fully closed (diaphragm not over-tight). Ball and plug valves ship fully open. Check-valve discs are closed and fixed (the fix must be removed before pressure testing). Flange faces and threaded ends must be protected with caps so the sealing surfaces arrive undamaged.
The top causes are: material mismatch (e.g. substituted bolts or castings not matching the MTR), shell-test leakage (outer leak at body/bonnet joint or casting defect), seat leakage (inner leak, often from dirt or a scratched seat), out-of-tolerance dimensions or wall thickness, coating peel-off, and unclear or missing nameplate/marking. Most are caught by a disciplined pre-shipment checklist plus PMI on alloys.