ASME STP-NU-078-2016 — Comparison Report on Welding Qualification and Welding Quality Assurance

28 10 月, 2026
ASME Standards

🔧 ASME STP-NU-078-2016 is a code comparison report prepared by Dr. Andrew Wasylyk of the World Nuclear Association and jointly sponsored by the U.S. Nuclear Regulatory Commission (NRC, award NRC-HQ-12-G-04-0059) and ASME ST-LLC. Using the ASME Boiler and Pressure Vessel Code (BPVC) Section IX (welding, brazing, and fusion qualifications) and Section III (nuclear facility component construction) as the baseline, the report systematically compares the requirements of the world’s major nuclear construction welding codes in three areas — qualification of welders and welding operators, the technical content of welding procedure specifications (WPS) and their qualification (PQR), and systems for technical management and supervision of welding (welding quality assurance) — providing an authoritative reference for cross-code certification and welding management in the global nuclear supply chain.

💡 The core value of this report is “translating” the rule differences across welding code systems: for the same weld, the coverage and limitation logic qualified under ASME Section IX, ISO, RCC-M, JSME, PNAE G-7, CSA, or KEPIC differ. Understanding these differences is the key to code transfer and to avoiding redundant requalification work.

1. Comparison Scope and Method 📌

Code systems compared in the report include:

ASME BPVC: Section IX + Section III (baseline);
ISO standards: ISO 9606-1 (welder qualification), ISO 14732 (welding operators), ISO 3834 (welding quality requirements);
French AFCEN RCC-M: French nuclear construction code;
Japanese JSME (e.g., JSME S NB1);
Russian PNAE G-7 (G-7-008-89, G-7-009/010-89, etc.);
Canadian CSA;
Korean KEPIC (KEPIC MN).

A uniform comparison scale is applied, with each requirement rated on a consistency hierarchy (e.g., A = essentially the same, B = partially similar, C = not similar), and all detailed comparison tables are reproduced in Mandatory Appendices I through IV.

⚠️ The report also addresses the influence of the EU Pressure Equipment Directive (PED 97/23/EC) on welding qualification: within the EU framework, welding for pressure equipment must be approved by a third party (a body recognized by a Notified Body), which differs fundamentally from the ASME model where the manufacturer qualifies procedures (under AI witness). Cross-regional supply must satisfy both sets of requirements.

2. Comparison of Welder and Welding Operator Qualification 🔬

The core differences among codes in welder qualification concern: the joint/position coverage of the certificate, validity and requalification mechanisms, and the separate treatment of welding operators for mechanized welding. Examples:

ASME Section IX manages qualification through “welder qualification tests + skill maintenance,” with relatively flexible validity and requalification rules;
ISO 9606-1 and ISO 14732 qualify manual welders and welding operators separately, with explicit validity and interruption rules (e.g., requalification after a 6-month break);
The PNAE G-7 series imposes unique requirements on material grouping (grade/group of grades) and classification of filler metals, whose groupings do not correspond one-to-one with ASME P-Numbers/F-Numbers.

Dimension	ASME Section IX	ISO 9606-1 / ISO 14732	PNAE G-7-010-89	RCC-M
Manual welder / welding operator	Both can be qualified	Qualified separately (9606-1 and 14732)	Specified separately	Specified separately
Base metal grouping	P-Number/Group	Material groups	Grade (group of grades) allowing multiple grades with the same filler	P-Number-like groups
Filler metal grouping	F-Number	Filler groups	By filler grade	By filler family
Qualified thickness range	QW-451 logic (incl. 5/8 in limit)	Coverage by plate/pipe thickness	By base metal thickness range (App. 1-4.1.4)	By thickness range
Certificate validity	Continuous use / requalification	Explicit validity and interruption rules	Certificate system	Certificate system

💡 Key difference to remember: ASME Section IX permits a groove weld test to qualify full- and partial-penetration groove welds and fillet welds, whereas some codes (e.g., PNAE G-7-010-89) require full/partial penetration groove welds and fillet welds to be qualified separately. Always verify the coverage logic when transferring codes.

3. Comparison of WPS Technical Content and Qualification 📊

The comparison of welding procedure specifications covers: the technical elements a WPS must contain (base metal, filler, preheat/interpass temperature, welding parameters, heat treatment, etc.), the form and inspection items of qualification test specimens, and the qualified coverage ranges (thickness, diameter, position, weld size). Mandatory Appendix II reproduces numerous detailed differences line by line, for example:

QW-403.5/403.11: requalification triggered by a change of Group within a P-Number, or a change from one P-Number to another or to an unassigned base metal, versus the PNAE G-7-010-89 “grade (group of grades)” logic;
QW-403.9: limits on the qualified thickness if any pass is thicker than 1/2 in (13 mm) — not applicable to GTAW;
QW-404.4: requalification on a change from one F-Number in QW-432 to any other, versus PNAE filler grade grouping rules;
QW-403.6: the minimum thickness qualified is T or 5/8 in (16 mm), whichever is less; where T is less than 1/4 in (6 mm), the minimum is 1/2T.

🚨 The most error-prone scenario is that a “nominally identical” WPS has different coverage under different codes. For example, the qualified groove weld thickness logic of ASME Section IX is not equivalent to the PNAE base metal thickness range logic; reusing an old qualification without a transfer assessment can create nonconformances and even delay release of nuclear-grade welds.

4. Comparison of Welding Quality Assurance Systems 🛠️

The third comparison area focuses on “systems for technical management and supervision of welding as a manufacturing/construction tool,” covering the qualification of welding responsible engineers/supervisors, preparation and issue of welding documents, filler metal control and traceability, NDE, and nonconformance handling. ISO 3834 (quality requirements for fusion welding of metallic materials) is the most representative system-level standard in this area, and the report compares it with ASME Section IX, RCC-M, PNAE G-7, and KEPIC. Principal conclusions include:

The ASME system achieves oversight through “quality assurance (QA) programs + AI witness + certificate holders”;
ISO 3834 uses levels (e.g., comprehensive, standard, elementary quality requirements) matched to product complexity;
National nuclear codes generally require independent third-party witness and documented traceability, but the division of responsibilities (welding engineer, inspector, NDE personnel qualification) differs.

Aspect	ASME Section IX	ISO 3834	RCC-M	KEPIC MN
System positioning	Procedural requirements + AI witness	Graded quality requirements	Nuclear-specific weld management	Korean system aligned with ASME
Welding responsible person	Per QA program	Defines welding coordinator duties	Welding engineer/supervisor qualification	References ASME
Filler metal control	Traceability requirements	Explicit receipt, storage, issue control	Dedicated control	References ASME
Third-party witness	AI witness of key activities	As required/of customer	Notified body / independent witness	References ASME

5. Future Harmonization Trends and Engineering Recommendations 📈

Section 8 of the report reviews upcoming code changes affecting global harmonization across the three areas: welder and welding operator qualification, the technical content of WPS and their qualification, and welding management systems are all trending toward international convergence. Recommended practices:

📋 Code transfer assessment: before cross-border delivery, execute the appendix comparison tables for existing WPS/PQR and welder certificates line by line to identify items requiring supplementary qualification;
🔍 Coverage logic check: focus on the four coverage categories — thickness, position, base metal grouping, and filler metal grouping — and add supplementary test coupons where necessary;
📊 Third-party interface: when supplying under the PED framework, agree early with the Notified Body on the welding qualification approval path;
🔧 System integration: combine ISO 3834 quality levels with the ASME QA program to establish a single weld management system file set acceptable to multiple code audits.

✅ In summary, the world’s nuclear welding codes are highly consistent in the goal of “ensuring weld quality”; differences lie mainly in qualification coverage logic and administrative procedures. Using the appendixes of this report as checklists for systematic comparison can significantly reduce cross-code certification cost while avoiding quality risks.

6. Frequently Asked Questions ❓

❓ Q: Can a WPS qualified under ASME Section IX be used directly on an RCC-M project?
A: Not directly. Although the technical content is similar, RCC-M’s definitions of base metal grouping, filler families, thickness coverage, and welder qualification differ from Section IX; requalification per RCC-M or a formal code-transfer assessment is normally required.

❓ Q: What is the relationship between ISO 3834 and ASME Section IX?
A: ISO 3834 is a system-level (graded) requirement for welding quality management, while ASME Section IX is the technical rule for qualifying welding procedures and welders. They are complementary: ISO 3834 governs the management system, Section IX the technical qualification.

❓ Q: Why does PNAE G-7 group materials differently from ASME?
A: PNAE G-7 groups by “grades of steel weldable with the same welding material,” whereas ASME groups by similar chemistry/mechanical properties into P-Numbers/F-Numbers. The same base metal can therefore fall into different groups and trigger different requalification conditions in the two systems.

❓ Q: What special requirements does the EU PED impose on welding qualification?
A: Under PED, welding procedures and welder qualifications for pressure equipment must generally be approved by a third party (recognized by a Notified Body) rather than qualified solely by the manufacturer; equipment must also satisfy the Essential Safety Requirements (ESRs) of Annex I, including supplementary weld requirements.