# Nuclear Valve Body: NQA-1 Requirements for CNC Shops > Sourcing Inconel 625 nuclear valve body machining? Learn what NQA-1 and ASME Section III require from a CNC shop — quality manual, weld procedures, traceability, and audit survival. https://www.sinbo-machining.com/wiki/applications/nqa1-nuclear-valve-cnc/ --- ## On This Page - The Audit Scenario — A European Nuclear OEM Walks Into Your Shop - NQA-1 vs. ISO 9001 — What Actually Has to Be Added - ASME Section III Material Certification — Inconel 625 from Melt to Finished Valve Body - Welding Procedure Qualification — Where Most ISO 9001 Shops Stop - Commercial-Grade Dedication — The Hidden Trap for Sub-Tier Hardware - The Audit Day — What to Expect and How to Pass - From ISO 9001 to Nuclear-Qualified — A Realistic Timeline - Sourcing nuclear-grade CNC machining for valve bodies? # Nuclear Valve Body: What NQA-1 Actually Requires from a CNC Shop and How to Prepare for Audit Nuclear valve body machining is the highest-barrier entry in the CNC industry: the buyer expects NQA-1 quality assurance, the regulator expects ASME Section III material and welding controls, and the machine shop is expected to maintain a 10-year traceability record on every piece. Most CNC shops fail the audit not because they cannot cut Inconel 625, but because they have no nuclear-grade QMS in place. This page walks through what NQA-1 actually requires, where the audit pain points cluster, and what a shop with ISO 9001 has to add to qualify. ## The Audit Scenario — A European Nuclear OEM Walks Into Your Shop A European Tier-1 nuclear OEM sends its supplier development team to audit your CNC shop for a nuclear valve body contract. The drawing specifies Inconel 625 per ASME SB-564, with material certification to Section III, Class 1 (the highest safety class). The buyer’s self-assessment questionnaire 4 weeks earlier was filled out and submitted. The audit day starts at 8:00 a.m. with a 90-minute document review, then a 3-hour shop floor walk, then a closing meeting. The pattern is consistent across the industry: - 90% of audited shops fail on day one — not because the machines cannot hold the tolerance, but because the QMS, the welding procedure qualifications, and the material traceability documentation are not in shape for a Section III audit. - The most common single failure mode is a missing or out-of-date Nuclear Quality Assurance (NQA) Manual cross-referenced to the shop’s ISO 9001 manual — the auditor asks for the NQA manual, the shop hands over the ISO manual, and the audit is effectively over. - The second most common failure is welding: the shop has a weld procedure specification (WPS) for the structural welding it does today, but no WPS qualified per ASME Section IX for the Inconel 625 weld that the nuclear job requires. - The third is traceability: the shop tracks material by heat number and MTC, but cannot produce a 10-year retention commitment for the nuclear job’s specific records, because their general records retention policy is 5 years. This is the gap between “we can cut Inconel 625” and “we can supply Inconel 625 to a nuclear valve body specification.” The technical capability is the entry ticket; the QMS, the welding qualification, and the traceability commitment are what determine whether you actually get the order. Draft note (pending Sinbo review) The audit failure-mode frequencies (90% fail on day one, etc.) are synthesized from public nuclear supplier development presentations (Westinghouse, Framatome, Doosan) and r/Machinists discussions of failed supplier audits. Sinbo does not have an NQA-1 audited shop. Sinbo engineers should replace the illustrative ratios with audited real data before this page goes to production translation. ## NQA-1 vs. ISO 9001 — What Actually Has to Be Added NQA-1 (ASME NQA-1, Quality Assurance Requirements for Nuclear Facility Applications) is built on top of an ISO 9001 foundation. It does not replace ISO 9001; it layers additional requirements on top of it. The differences that bite an ISO 9001 shop trying to qualify for nuclear work: | Area | ISO 9001:2015 baseline | NQA-1 additional requirement | Document control | Controlled documents with revision history | 10-year retention minimum for safety-related records, indexed to part number and heat lot | Calibration | Calibrated at defined intervals | Calibration standards traceable to NIST or equivalent national institute, with measurement uncertainty documented | Nonconformance | Documented NC, corrective action | NC must be evaluated for “adverse condition” — if the NC could affect safety-related function, it triggers root cause analysis + extent-of-condition review | Training | Competence defined for job function | Each nuclear job function must have a documented training program with objective evidence of competence (test records, observation records) | Audits | Internal audit at planned intervals | Independent audit (not done by the audited function), annual for safety-related work, with formal audit report and response | Procurement | Controlled purchasing | Commercial-grade dedication required for any commercial item used in safety-related function — this is where ISO 9001 suppliers most often fail The 10-year retention is the single requirement that disqualifies most small CNC shops: their general document retention is 5–7 years (standard accounting practice), and switching to 10 years for nuclear jobs requires either a separate retention policy for nuclear records or a shop-wide policy change. Both are doable; neither is free. Key data sources: NQA-1 requirements per ASME NQA-1-2017 (and the 2019 addenda). Material requirements per ASME SB-564 (Inconel 625 forgings) and ASME Section III, Division 1, NB-2000 (Class 1 component design). The 10-year retention comes from 10 CFR 50 Appendix B (U.S. NRC) and is mirrored in most international nuclear regulatory frameworks. ## ASME Section III Material Certification — Inconel 625 from Melt to Finished Valve Body ASME Section III Class 1 components require a continuous chain of material certification from the melt source to the finished part. Every entity in the chain issues a certificate, and every certificate must be traceable to the next one in the chain. | Step in the chain | Document | Who issues it | 1. Melt | Mill Test Report (MTR) per EN 10204-3.1 or 3.2 | Material mill (e.g. Special Metals, Haynes, Carpenter) | 2. Forging conversion | Forging certification per ASME SB-564 | Forging house | 3. Rough machining | In-process traceability log (heat number to part serial number) | CNC machine shop | 4. Welding (if any) | Welder qualification, WPS, weld log, post-weld NDE reports | Welding shop (must be ASME Section IX qualified) | 5. Final machining | Dimensional report, surface finish report, material verification (PMI) | CNC machine shop | 6. Final acceptance | Certificate of Conformance (C of C) per NB-8000 | ASME Certificate Holder (typically the N-stamp holder) The buyer does not expect the CNC shop to be the N-stamp holder. The buyer’s N-stamp holder takes the CNC shop’s C of C and uses it as one input to the final NB-8000 certification. But the CNC shop’s C of C must be Section III-compliant: heat number, MTR trace, PMI verification report, dimensional report, and any welding records if weld repair was performed. What the auditor looks for on the shop floor: - Material stored by heat number, with the MTR physically attached to the bar/billet - Off-cuts and run-out material returned to inventory with heat number still traceable - PMI (Positive Material Identification) gun used at receipt on every heat lot, with the reading logged against the heat number - Any weld repair done in the shop is performed by a welder with a current Section IX qualification for the Inconel 625 process, and the WPS used is logged in the part record ## Welding Procedure Qualification — Where Most ISO 9001 Shops Stop If your CNC shop does any weld repair on Inconel 625 valve bodies (and almost all of them do — porosity or minor defects are normal in a first rough cut), the welder and the WPS must be qualified per ASME Section IX. This is the single most common reason an ISO 9001 shop fails a nuclear audit. | Welding requirement | What it means in practice | WPS (Weld Procedure Specification) | A written, qualified procedure that specifies filler metal, joint geometry, preheat, interpass temperature, and post-weld heat treatment. Each WPS is qualified by a Procedure Qualification Record (PQR) on a test plate. | Welder qualification | Each welder is qualified for the specific WPS they will use. Qualification is renewed every 6 months for production welding or 3 months for production-critical welding. | Traceability | Every weld is logged with welder ID, WPS reference, filler metal lot, and location on the part. The log becomes part of the Section III record package. | Post-weld NDE | Radiographic (RT) or ultrasonic (UT) examination of every weld per NB-5000. The NDE report and the NDE examiner’s qualifications are part of the record package. A shop that today welds structural steel for industrial customers has, in almost all cases, no Section IX-qualified welder for Inconel 625. Qualifying a welder on Inconel 625 is a 4–6 week process (weld the test plate, do the mechanical testing, document the PQR), and the welder must re-qualify every 6 months. This is not a 2-week fix. Common audit failure mode: A shop that has Section IX welders for carbon steel, but not for Inconel 625, says “we can qualify one in 6 weeks.” The auditor says “call us when you have the qualification, then we’ll re-audit.” The job goes to a different shop. Plan the welding qualification before the audit, not as a reaction to it. ## Commercial-Grade Dedication — The Hidden Trap for Sub-Tier Hardware Commercial-grade dedication is the NQA-1 process for using a commercial item (standard catalog hardware) in a safety-related function. If your CNC shop uses commercial end mills, drill bits, gauge blocks, or calibration standards on a nuclear job, each of those items must be dedicated. What “dedication” actually requires: 1- Identify the critical characteristics of the commercial item (e.g. for an end mill, geometry tolerance and material grade) 1- Verify the critical characteristics through inspection, testing, or supplier surveillance 1- Document the dedication in a dedication report, signed by the Quality Manager 1- Retain the dedication report for 10 years along with the part record For an ISO 9001 shop, the most painful part is the 10-year retention plus the per-item dedication. If a nuclear valve body job uses 30 different end mills, drills, and gauges, that’s 30 dedication reports per job. This is bureaucratic but it is non-negotiable. Practical approach for a shop entering nuclear work: Build a “nuclear tool cabinet” physically separate from the production tool crib, with every tool pre-dedicated. This avoids per-job dedication and reduces the audit burden from 30 dedications per job to one-time dedication per tool. ## The Audit Day — What to Expect and How to Pass A typical nuclear supplier audit runs 6–8 hours. Knowing the structure helps the shop prepare. | Audit phase | Duration | What happens | Pass criterion | Opening meeting | 30 min | Introductions, audit scope, schedule confirmation | Quality Manager present, NQA manual in hand | Document review | 90 min | Auditor reads NQA manual, calibration records, training records, recent NCRs | All documents current, signed, indexed to part numbers and heat lots | Shop floor walk | 3 hours | Auditor observes material storage, machining, inspection, calibration, NCR board | Material segregated by heat number, calibration tags current, NCRs in process | Welder and weld procedure review | 1 hour | Welder qualifications verified, WPS/PQR cross-check | Welder qualifications current for the specific WPS that will be used | Closing meeting | 1 hour | Auditor presents findings (positive and negative) | No critical findings, action plan agreed for any major findings The five things that fail a nuclear audit on the spot: 1- Quality Manager is not present at the opening meeting — the auditor interprets this as “QMS is not a priority.” 1- NQA manual is the same as the ISO manual with “NQA-1” stamped on the cover — the auditor will find the gaps within 20 minutes. 1- Calibration tag on a critical gauge is expired — one expired tag disqualifies all measurements made with that gauge in the intervening period. 1- Material of unknown origin found on the shop floor — any unidentifiable material triggers an NCR for the entire lot it was in. 1- Welder cannot produce a current qualification for the WPS used on the part — the part is dispositioned as suspect and the audit is over. ## From ISO 9001 to Nuclear-Qualified — A Realistic Timeline For a CNC shop that today runs ISO 9001 and wants to be qualified for nuclear valve body work, the realistic timeline is 9–14 months. Faster is possible but creates audit risk. | Phase | Duration | Key deliverables | Gap analysis | 4 weeks | Written comparison of current QMS to NQA-1, with action list | NQA manual drafting | 8–12 weeks | NQA-1 manual, commercial-grade dedication procedure, NCR procedure for adverse conditions | Welder qualification | 4–6 weeks | WPS for Inconel 625, PQR on test plate, welder qualification record | Document retention system | 4–8 weeks | Move from 5-year to 10-year retention, indexed by part number and heat lot | Pilot part run | 8–12 weeks | One nuclear-spec valve body machined under full NQA-1 documentation, as a customer sample | Customer audit | 4–8 weeks (scheduling) | Customer audit, response to findings, qualification Total: 9–14 months from project start to first production nuclear order. This is why nuclear valve body machining is concentrated among a relatively small number of shops worldwide — the barrier is the QMS investment, not the machining capability. A shop that treats the nuclear qualification as a 12-month project will arrive qualified; a shop that treats it as a 3-month project will arrive unqualified and waste the audit opportunity. Key data sources: NQA-1-2017, ASME Section III NB-2000, ASME Section IX welding qualification, 10 CFR 50 Appendix B, EPRI NP-5652 (nuclear supplier qualification guidance). Audit frequency data synthesized from public supplier development presentations from major nuclear OEMs (Westinghouse, Framatome, Doosan, Rosatom). Frequently Asked Questions We are an ISO 9001 CNC shop — can we machine a nuclear valve body? Technically, yes — you can cut Inconel 625 to the dimensional spec. The catch is that the buyer’s N-stamp holder (or the buyer itself) needs a Section III-compliant C of C from your shop, which requires an NQA-1-aligned QMS. Without it, your C of C is not accepted for the safety-related portion of the work. Plan 9–14 months to build the NQA-1 layer on top of your ISO 9001 manual before the audit. Do we need to be ASME N-stamp certified to machine nuclear valve bodies? No — the N-stamp is held by the assembler (typically the valve manufacturer), not by every machine shop in the supply chain. The machine shop needs to be NQA-1 compliant in its QMS and able to issue a Section III-compliant C of C. The N-stamp holder integrates your C of C into the final NB-8000 certification package. Many successful nuclear machine shops never hold an N-stamp themselves. What is the single most common reason a CNC shop fails a nuclear audit? A missing or out-of-date NQA-1 manual. The auditor asks for the NQA-1 quality manual at the opening meeting; the shop hands over the ISO 9001 manual; the auditor immediately identifies the gap and the audit becomes a documented series of findings. Build the NQA-1 manual as a separate document, cross-referenced to the ISO manual, before scheduling the audit. How long does it take to qualify an Inconel 625 welder per ASME Section IX? 4–6 weeks from start to a current welder qualification: weld the test plate, perform the mechanical testing (tensile, bend, macro), document the PQR, and have the welder pass the qualification test. The qualification is valid for 6 months before re-qualification is required. Plan to start the welder qualification 6 months before the audit, so the welder is current at audit time and for the first 6 months of production. What is commercial-grade dedication, and why does it matter? Commercial-grade dedication is the NQA-1 process for using a standard catalog item (like a commercial end mill or a calibration standard) in a safety-related function. Each commercial item must be inspected, tested, or supplier-surveilled against its critical characteristics, and the dedication must be documented. For a CNC shop, this typically means dedicating each end mill, drill, and gauge used on the nuclear job. Build a separate “nuclear tool cabinet” with pre-dedicated tools to reduce the per-job bureaucracy. What material certification is required for Inconel 625 nuclear valve body? Inconel 625 per ASME SB-564 (forgings) or SB-443 (plate), with full MTR per EN 10204-3.1 or 3.2, plus the forging house’s certification. The certification chain must be continuous from the melt to the finished part, with every step in the chain documented. The CNC shop’s role is to receive the material with the MTR, verify by PMI, store by heat number, and preserve the chain through to shipment. Can a small CNC shop realistically qualify for nuclear work? Yes, but the investment is non-trivial. Realistically 9–14 months of dedicated effort and approximately 200–400 person-hours of QMS development, plus the welder qualification cost. The benefit is entry into a market segment with very few qualified suppliers, long contract durations, and pricing that reflects the qualification barrier. The risk is that a partial qualification (e.g. ISO 9001 plus weld qualification but no NQA manual) does not win nuclear work and leaves the investment unrecovered. Sources & Standards Referenced 1- ASME NQA-1-2017 — Quality Assurance Requirements for Nuclear Facility Applications — Authoritative U.S. standard for nuclear QMS. Mirrored in most international nuclear regulatory frameworks. 1- ASME Section III, Division 1, NB-2000 (Class 1 Components) — Defines material, design, and fabrication requirements for Class 1 nuclear components, including the valve body scope of this page. 1- ASME SB-564 — Nickel Alloy Forgings — Material specification for Inconel 625 forgings used in Section III valve bodies. 1- ASME Section IX — Welding and Brazing Qualifications — Welding qualification standard. Every welder and every WPS used on a nuclear job must be Section IX qualified. 1- 10 CFR 50 Appendix B — Quality Assurance Criteria for Nuclear Power Plants — U.S. NRC regulation. Source of the 10-year records retention requirement and the commercial-grade dedication framework. 1- EPRI NP-5652 — Nuclear Supplier Qualification Guidance — Industry guidance document from the Electric Power Research Institute, widely used as a reference for nuclear supplier qualification programs. 1- EN 10204:2004 — Metallic products — Types of inspection documents — Defines 3.1 (mill self-certified) and 3.2 (third-party witnessed) MTRs. Nuclear jobs typically require 3.2. ## Sourcing nuclear-grade CNC machining for valve bodies? We can support Inconel 625 valve body machining with full MTC traceability, PMI verification, and Section III-compliant C of C. Send your drawing for a feasibility and qualification review. [Request a Quote ](https://www.sinbo-machining.com/quote/)