Home › Guides › Free valve inspection checklist (PDF)

Free buyer’s valve inspection checklist: before the PO, during production and before shipment

A three-stage checklist written from the inspector’s side of the test bench — what to fix in the PO, what to see while valves are still bare metal, and the 12 areas we cover at pre-shipment inspection. Free PDF, no email required.

General Inspection2026-11-149 min read

checklistPSIDUPROfree PDF

Short answer: A useful valve inspection checklist has three stages: fix the standard, edition, leakage rate, AQL plan and hold points before the PO; check materials, bare castings and pre-paint tests during production; then run a 12-area pre-shipment inspection. Download the free A4 PDF below — no email required.

By Kevin Lyu (吕中国), ValveWitness Inspection, Ningbo · Published 2026-11-14

Download the checklist (PDF, A4)See a sample report

How to use it: print stage 1 and attach it to your PO, send stage 2 to the factory with the expected DUPRO date, and keep stage 3 for the inspection day. Every step should leave a record — a photo, a reading or a signature.

Stage 1 — Before booking: what to fix in the purchase order

Most arguments at the test bench start with a PO that says “API 598” and nothing else. Agree these points in writing before production starts.

CheckWhat to fix before the PO
Standard and editionName the design and test standards with year, e.g. API 600 + API 598:2023, or EN 12266-1:2012. “API 598” with no year invites argument later.
Leakage rateFor ISO 5208 / EN 12266-1 write the lettered rate (e.g. “Leakage rate A”). For API 598 state seat type and any optional tests.
Hold times and test fluidsConfirm the factory’s procedure uses the minimum durations of your edition, and which tests are water and which are air or inert gas.
AQL planISO 2859-1 or ANSI/ASQ Z1.4, inspection level (usually General II) and AQL per defect class: critical, major, minor.
Drawing and tolerancesAn approved drawing with critical dimensions and tolerances marked: face-to-face, flange OD, bolt circle, raised-face diameter, bore.
Test and inspection scopeWhich tests the factory runs on 100% of valves, how many you witness, and which steps are hold points (no shipment until released).
Documents requiredEN 10204 3.1 (or 3.2) certificates, 100% test records, gauge calibration certificates, packing list — and when they must be ready.

Stage 2 — During production (DUPRO)

Book DUPRO when roughly 30–50% of bodies are machined and still unpainted. This is the last point where casting faults, heat-number gaps and dimensional drift are cheap to fix. See PSI vs DUPRO.

CheckWhat to see during production
Raw material and MTCEN 10204 3.1 certificates match heat numbers cast or stamped on bodies and bonnets; chemistry and mechanicals match the ordered grade.
Casting / forging visualBare castings and forgings: sand holes, cracks, cold shuts, porosity, repaired areas — before paint hides them.
Critical machined dimensionsSample critical dimensions on machined parts against the drawing: seat bores, stem diameters, flange faces and facing finish.
Pre-paint pressure testingShell and seat tests run on bare, dry valves, so weeping through the body or a pinhole is visible. Witness here if testing is a hold point.
Trend checkRecurring defects across the first batch are cheaper to fix now than at PSI. Record serials of anything set aside.

Stage 3 — Pre-shipment inspection: the 12-area field checklist

This is the order we work in on site. Sampling follows ISO 2859-1 or ANSI/ASQ Z1.4; marking follows MSS SP-25 or EN 19; tests follow the shell, seat and backseat sequence your PO names.

AreaWhat the inspector checks
1. Readiness gate100% of the order finished and at least 80% packed. If not, the visit may be postponed or reported as PENDING.
2. Documents and gaugesMTCs, 100% factory test records, gauge ID and calibration validity; thickness gauge checked with foils before use.
3. Quantity and random selectionCount cases and pieces against PO and packing list. The inspector — not the factory — picks the sample cartons for AQL.
4. MarkingsBody marks and nameplate to MSS SP-25 or EN 19 as the PO requires: maker, material, rating, size, heat number, flow arrow.
5. DimensionsFace-to-face, flange OD, bolt circle, hole diameter, raised-face diameter and facing finish against drawing and standard.
6. Visual workmanshipCastings, sealing faces, paint runs, missing parts, bolt threads, bore cleanliness. Each defect classed critical, major or minor.
7. Pressure test witnessShell → backseat (if fitted) → high-pressure seat → low-pressure air seat, as the PO requires. Gauge, serial and timed hold recorded.
8. OperationFull open / close; smooth, no binding. Handwheel turns or operating torque against the drawing or data sheet; no gland leak after.
9. Coating DFT and colourReadings per sample at agreed points (body, bonnet, flange back); average and minimum recorded; shade checked against the RAL card.
10. PMI (only if ordered)Portable XRF on stem, body and seat overlay, verified against a check standard. Supports, never replaces, the MTC.
11. Packing and ISPM 15Flange end covers fitted, valve position per spec, preservation, ISPM 15 mark on wood, shipping marks match the PO.
12. Witness log and closing recordFacts explained to the factory; defect list acknowledged in writing. Report in English, normally within 24 hours.

Quick checkpoints by valve type

On top of the 12 areas, each valve type has a few points that are easy to miss.

Gate valves

CheckpointWhat to look for
Wedge and seatSeat rings and wedge faces free of scratches; wedge travel full and centred.
Backseat testApplies only where a backseat is fitted; valve fully open.
Stem and turnsStem straight, threads clean; handwheel turns to full open recorded.
Face-to-faceASME B16.10 or EN 558 series named in the PO.

Ball valves

CheckpointWhat to look for
Floating or trunnionConfirm the design matches the data sheet; seat material as ordered.
Cavity and specialsCavity relief, anti-static device or DBB tests only where specified — and witnessed if they are.
Ball and seatsBall surface finish, seat insert condition, stops aligned with port.
Operating torqueSmooth quarter turn; torque or actuator sizing to the data sheet.

Butterfly valves

CheckpointWhat to look for
Disc clearanceDisc swings clear of the pipe bore and adjacent flange ID for the stated schedule.
Liner and seatRubber or PTFE liner bonded, no cuts or blisters; seat test from the direction(s) in the PO.
Lug and waferLug threads and bolt holes to the flange standard; centring holes on wafer bodies.
Gearbox / actuatorMounting orientation, position indicator, travel stops set at open and closed.

Check valves

CheckpointWhat to look for
Flow arrowArrow cast or plated in the correct direction; matches the nameplate.
Disc movementDisc, hinge pin or spring moves freely; silent / nozzle types close without sticking.
Seat test directionSeat test applied from the downstream side — and a low-pressure air seat test if ordered.
OrientationSuitability for horizontal or vertical installation as stated on the data sheet.

Evidence rules we follow — and you can ask any inspector for

  • Every photo carries a date, time and location watermark; an overview shot first, then a close-up.
  • Defect photos include a ruler and the serial or case number.
  • Gauge readings — pressure gauge, thickness gauge, caliper — are readable in the photo.
  • Each pressure hold is filmed with the gauge and the valve in the same frame, where the factory permits.
  • Anything not seen is written as “Not witnessed”, never assumed.
  • Original photos are kept and delivered as a pack; nothing is deleted.

The three things that decide most inspections

  • A PO that names the standard, the edition, the leakage rate and the AQL plan.
  • Hold points that put the inspector at the bench before paint, not after crating.
  • A readiness gate: 100% finished and at least 80% packed before the PSI visit.

Download the checklist PDF · Sample report · Request an inspection

Questions buyers ask

Is the checklist really free?

Yes. The PDF is a direct download with no email form. You may print it and share it with your own team and suppliers.

Does the checklist replace the standards?

No. It tells you what to check and when. Test pressures, hold durations, leakage values and AQL acceptance numbers must be read from the licensed standard edition named in your PO.

Can I send the checklist to my supplier?

Yes — sending it with the PO is a good way to agree hold points, documents and the readiness gate before production starts.

Sources

  • API 598, Valve Inspection and Testing — API publications store
  • ISO 5208:2015, Industrial valves — Pressure testing of metallic valves — iso.org
  • EN 12266-1:2012, Industrial valves — Testing of metallic valves — Part 1 — BSI (BS EN 12266-1:2012)
  • ISO 2859-1, Sampling procedures for inspection by attributes — iso.org
  • EN 10204, Metallic products — Types of inspection documents — BSI
  • MSS SP-25, Standard Marking System for Valves, Fittings, Flanges and Unions — MSS
  • ISPM 15, Regulation of wood packaging material in international trade — IPPC

Related services: pre-shipment inspection, DUPRO and pressure test witnessing.

We report facts from the samples inspected. Standards named in these guides are public standards we work to, not certifications or accreditations we hold. We do not issue product certificates or accreditation marks. Test pressures, durations, leakage rates and acceptance numbers must be read from the licensed edition named in your purchase order; we do not reproduce copyrighted tables from the standards.

Related

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.

Related

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.

Related

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.

Need an inspector at a Zhejiang factory?

Send your PO or specification, the factory city and the date. We confirm scope and price within one working day.

Request an inspectionWhatsApp +86 131 2757 0627