Free valve inspection checklist (PDF)
Printable A4 checklist (no email gate): pre-PO verification, DUPRO checks, the 12-area PSI field list and quick checkpoints for gate, ball, butterfly and check valves.
checklistPSIDUPROfree PDF
Read the guide →Home › Guides
Valve inspection knowledge & standards
Practical, post-style guides to the standards in our sample report, to everyday inspection checks, and to how US and European requirements differ.
These are practical, post-style guides to the standards that appear in our sample valve pre-shipment inspection report, the checks we use on a typical PSI, and the points where US (API, ASME, MSS, SSPC) and European (EN, ISO) requirements diverge. They are written from the inspector’s side of the factory floor. They are not a substitute for the licensed standard named in your purchase order, and they are not product certificates.
New — free buyer’s valve inspection checklist (PDF): pre-PO checks, DUPRO, the 12-area PSI field list and quick points for gate, ball, butterfly and check valves. Download the PDF (no email required) or read it online.
API 598 vs EN 12266-1 vs ISO 5208
Which pressure-test standard is in your PO, how API 598, EN 12266-1 and ISO 5208 differ, and how API 6D changes the job for pipeline valves.
API 598EN 12266-1ISO 5208API 6D
Read the guide →ISO 2859-1 vs ANSI/ASQ Z1.4
How General Level II and special levels S-3/S-4 set the sample size, how Ac/Re numbers work, and why a DFT deviation is not counted in the visual AQL tally.
ISO 2859-1ANSI/ASQ Z1.4AQLPSI
Read the guide →EN 10204 3.1 vs 3.2 and PMI
What 2.1, 2.2, 3.1 and 3.2 certificates actually mean, how heat numbers must trace to the body, and why XRF cannot measure carbon in WCB or L-grades.
EN 102043.13.2PMIXRF
Read the guide →MSS SP-25 vs EN 19 valve marking
Body marks versus nameplate items, heat/melt numbers, unidirectional flow arrows, and what CE/PED adds for valves sold into Europe.
MSS SP-25EN 19CEPEDnameplate
Read the guide →ASME B16.5 vs EN 1092-1 flanges
Why Class 150 is not PN16 or PN25, which flange and face-to-face dimensions a PSI actually measures, and how API 600 / ASME B16.34 relate to EN 1984.
ASME B16.5EN 1092-1ASME B16.10EN 558API 600
Read the guide →ISO 19840 vs SSPC-PA 2 and ISPM 15
ISO 19840’s 80/20 rule versus SSPC-PA 2 spots, a worked DFT example from the sample report, and what ISPM 15 marks and flange protection should look like.
ISO 19840SSPC-PA 2ISO 2808ISPM 15DFT
Read the guide →PSI vs DUPRO vs test witness vs loading
What each inspection stage actually covers, why a late PSI can miss casting and dimensional faults under paint and crates, and how to write hold points into your PO.
PSIDUPROtest witnessingloadingfactory audit
Read the guide →How to read a valve pressure test report
The fields every valve test record needs — serial and heat numbers, gauge ID, fluid, hold times, readings — and six red flags that make a factory test sheet worthless.
test reportAPI 598gauge calibrationred flags
Read the guide →Shell, seat and backseat valve tests explained
What each production pressure test proves, why the order matters, why bare dry metal matters, and a check valve that passed an 18 bar water seat test but leaked on 6 bar air.
shell testseat testbackseatair seat test
Read the guide →Valve inspection cost in China
Published ValveWitness rates — USD 220–260 per man-day in Ningbo, witness add-on, half-day witness, travel — and what makes a valve inspection take more than one man-day.
pricingman-daytravelbudget
Read the guide →How to verify a Chinese valve supplier
Check the business licence and scope on gsxt.gov.cn, tell a trading company from a real workshop, see the test bench on video, and set trial-order hold points.
supplier verificationgsxt.gov.cnfactory auditMTC
Read the guide →Zhejiang valve clusters: a buyer’s map
Ningbo, Wenzhou (Oubei, Longwan), Taizhou (Yuhuan, Wenling) and Lishui: what each area typically makes, rail and road times from Ningbo, and multi-factory trip planning.
WenzhouTaizhouNingbotravel planning
Read the guide →ISO 5208 and EN 12266-1 leakage rates
What the lettered leakage rates A to G mean, why “no visible leakage” differs between water and air tests, soft vs metal seats, and how to write the rate into your PO.
ISO 5208EN 12266-1API 598leakage rate
Read the guide →Standards in our sample report — quick map
Each section of the sample PSI report points to the standard we checked against, and to the guide that explains it.
| Report section | Standard(s) in the example | Guide |
|---|---|---|
| 2. Order information & documents | EN 10204 material certificates; design/test standards named on the PO (API 600, API 598, ASME B16.5 / B16.10 in the example) | EN 10204 3.1 vs 3.2 and PMI; flanges & face-to-face; pressure-test standards |
| 3. AQL sampling (and Section 1 conclusions) | ISO 2859-1 / ANSI/ASQ Z1.4, General Level II, Critical / Major / Minor, PASS / FAIL / PENDING | ISO 2859-1 vs ANSI/ASQ Z1.4 |
| 5. Packing & shipping marks | ISPM 15 wood packaging, flange caps, bore preservation, shipping marks | Coating DFT and ISPM 15 |
| 6–7. Visual / workmanship and dimensions | ASME B16.5 flange dimensions and raised-face serration; ASME B16.10 face-to-face (or EN equivalents if named) | ASME B16.5 vs EN 1092-1 and B16.10 vs EN 558 |
| 8. Marking & nameplate | MSS SP-25 (EN 19 on a European order), including heat / melt identification | MSS SP-25 vs EN 19 |
| 9. Pressure-test witness | API 598 in the example; or API 6D, EN 12266-1 or ISO 5208 if the PO names them | API 598 vs EN 12266-1 vs ISO 5208 |
| 11. Coating thickness (DFT) | ISO 2808 measurement; ISO 19840 or SSPC-PA 2 acceptance; RAL shade | ISO 19840 vs SSPC-PA 2 |
| 12. PMI (optional) | Portable XRF grade check; carbon not measured; supports, and does not replace, the MTC | EN 10204 and PMI |
Download the sample report (PDF) — all data are fictitious and marked EXAMPLE. Inspection types themselves are compared in PSI vs DUPRO vs test witnessing vs loading vs audit.