Fusion welding is often used in high-risk applications (e.g. pressure vessels, pipelines, bridges, offshore platforms). Poor-quality welds can lead to catastrophic failures.

Auditing welding companies and suppliers is essential to ensuring safety, reliability, and compliance in industries where welded components are critical to structural integrity. Auditing verifies that proper welding practices are followed and that welds meet mechanical and metallurgical requirements. It ensures that companies comply with international codes and client specifications, which is often a contractual or regulatory requirement.

Most welding fabrication companies require their welding engineers to understand international standards that define quality requirements for fusion welding of metallic materials – example ISO 3834. While ISO 9001 outlines the general principles of a quality management system (QMS) for any industry, ISO 3834 adds the essential technical depth needed where welding is a critical process. It includes quality controls for:

• Personnel qualifications
• Welding consumables
• Welding equipment
• Weld procedures (WPS/PQR)
• Inspection and traceability

By integrating ISO 3834 into an ISO 9001-based QMS, companies can build a comprehensive, welding-specific quality assurance framework. This ensures welding activities meet global standards for quality, safety, and traceability. The key linkages Between ISO 9001 and ISO 3834 can be summarised in Table 1.

Table 1: ISO 3834 and ISO 9001-based QMS linkage

ISO 9001	ISO 3834
Quality Management Principles	Specific requirements for welding quality assurance
Clause 8 – Operational Control	WPS/WPQR, welder qualification, material traceability
Risk-Based Thinking	Weld defect prevention, non-conformance control
Documentation & Records	Welding coordination, inspection records, test certificates

Why ISO 3834 is Key for Welding Audits

ISO 3834 is the most relevant and widely adopted standard for auditing welding supply chains. It offers a structured and thorough framework for assessing:

• Welding coordination and personnel competence
• Subcontractor control
• Material and filler management
• Welding procedures and qualifications
• Inspection and testing
• Documented traceability and quality records

ISO 3834 is the go-to standard when auditing fabricators, welders, welding consumable suppliers, and QA/QC systems involved in welding operations. Some areas typically covered are:

1. Confirming competence of welding personnel

Weld quality heavily depends on the competence of welders, inspectors, and welding coordinators. Audits verify:

• Valid welder qualifications (ISO 9606, ASME IX)
• WPS/PQR approvals (ISO 15614)
• Qualifications of inspectors (e.g. ISO 9712)

2. Ensures traceability of materials and consumables

Welding involves many critical materials – the base metals, filler wires, shielding gases. Auditing ensures:

• Material certificates are valid and traceable
• Consumables are stored correctly and tracked by batch
• This is vital for root-cause analysis and failure investigations.

3. Verifies control of welding procedures and inspection

Audits assess if:

• Approved welding procedures (WPS) are followed
• Pre- and post-weld inspections are conducted
• NDT methods and acceptance criteria meet the standards
• Repair processes are correctly implemented and recorded

Benefits of auditing welding companies and suppliers

1. Demonstrates due diligence and builds client trust

Certified audits (e.g., ISO 3834-2) provide third-party verification that a company’s welding operations meet high standards. This enhances:

• Bidding competitiveness
• Client confidence
• Legal defensibility in the case of disputes or failures

2. Enhances supply chain reliability

Auditing suppliers of welding services or materials ensures:

• Subcontractors follow the same quality standards
• Consistent quality across all project contributors
• Early identification of potential risks in the supply chain

3. Supports continuous improvement

Audit findings (non-conformances, observations) highlight areas for improvement. This drives:

• Better process control
• Cost savings by reducing rework and scrap
• Ongoing technical and quality development

A practical audit checklist based on ISO 3834 – Quality Requirements for Fusion Welding of Metallic Materials, that can be used to assess welding companies and suppliers may look as follows:

1. General Quality Management

Audit Area	Description	Yes/No	Comments
QMS Integration	Is ISO 3834 integrated with ISO 9001 or other QMS?
Welding Quality Manual	Is there a documented welding quality manual or procedures?
Management Responsibility	Are roles and responsibilities clearly defined?

2. Welding Coordination Personnel

Audit Area	Description	Yes/No	Comments
Competence	Is there a responsible Welding Coordinator (e.g. IWE, IWT)?
Qualification	Do they hold valid certifications (ISO 14731, IWE/EWE)?
Availability	Is the welding coordinator involved in project planning and execution?

3. Welder and Operator Qualifications

Audit Area	Description	Yes/No	Comments
Welder Certs	Are welders qualified (valid certification) as per ISO 9606 / ASME IX / API 1104?
Validity	Are qualifications up to date and traceable?
Continuity Logs	Is continuity of welder performance monitored and documented?

4. Welding Procedures (WPS / PQR)

Audit Area	Description	Yes/No	Comments
Procedure Availability	Are WPSs available for all welding operations?
Welding procedures	Are WPS/PQR compliant (ISO 15614, ASME IX)
Approval	Are procedures approved as per ISO 15614 / ASME IX?
Procedure Control	Is there a register of all qualified procedures?

5. Equipment and Facilities

Audit Area	Description	Yes/No	Comments
Calibration	Are welding machines and measuring instruments calibrated?
Maintenance	Is equipment regularly maintained and records available?
Environmental Control	Are conditions suitable for welding (humidity, temperature, cleanliness)?

6. Materials and Consumables control

Audit Area	Description	Yes/No	Comments
Certification	Are material and filler metal certificates available (EN 10204)?
Consumables	Are Batch tracking, storage conditions, supplier certs available?
Traceability	Is traceability maintained from receipt to use? (e.g. traceability by heat number)
Storage	Are consumables stored per manufacturer and code requirements?

7. Inspection and Testing

Audit Area	Description	Yes/No	Comments
NDT Personnel	Are inspectors certified to ISO 9712 / SNT-TC-1A?
NDT Procedures	Are inspection methods documented and qualified?
Inspection Records	Are visual/NDT records complete and traceable to welds?
Mechanical Testing	Is testing done by approved labs with proper methods?

8. Documentation and Records

Audit Area	Description	Yes/No	Comments
Welding Records	Are weld maps, logs, and inspection records properly maintained?
NCRs & Repairs	Are non-conformances documented and corrective actions taken?
Final Dossier	Is a full welding data package compiled for delivery/client?

9. Subcontractor Control

Audit Area	Description	Yes/No	Comments
Qualification	Are subcontractors qualified and approved?
Oversight	Is their welding work monitored/audited?
Documentation	Do subcontractors provide all required documentation?

10. Delivery and Product Release

Audit Area	Description	Yes/No	Comments
Final Inspection	Is the product inspected before dispatch?
Traceability	Can all welds and materials be traced?
Certificates	Are EN 10204 3.1/3.2 certificates provided where required?

Other relevant standards or sector-specific standards for auditing welding supply chains are:

1. EN 1090 – Structural Steel and Aluminium execution (EU/UK)

• EN 1090-2: Carbon and stainless steel
• Requires ISO 3834 compliance for welding and traceability
• Required for CE-marked construction products

Covers: Factory Production Control (FPC), Welding coordination responsibilities (e.g., IWE/IWT) and Material traceability.

2. ASME Section IX + NQA-1 (USA) – Nuclear Welding

• ASME IX governs welder and WPS qualification
• NQA-1 applies to nuclear quality assurance programs

3. ISO 3183 & API 5L – Line Pipe Standards

• Focus on steel pipes for petroleum and gas pipelines
• Covers manufacturing control, NDT, mechanical testing, traceability
• Site welding audits still refer to ISO 3834 and ASME/AWS

4. ASME B31 Code Series – In-Service Piping

• B31.3         Process piping (e.g. refineries, chemical)
• B31.4        Liquid transportation pipelines
• B31.8         Gas transmission and distribution
• ASME B31 projects rely on ASME IX for WPS and welder qualification.

5. AWS QC and AWS D1.1 (North America) – Structural Welding

• For welder and procedure qualification
• Commonly used in structural and industrial fabrication audits

6. Additional Supporting Standards

• ISO 14731 – Defines welding coordination responsibilities
• ISO 9606 / ISO 15614 – Welder and procedure qualifications

Summary: Some Standards for Welding Supply Chain Audits

Summary: Some standards for welding supply chain audits

Application	Relevant Standards
Structural steel fabrication	ISO 3834, EN 1090, ISO 9606, ISO 14731
Pipeline welding (site)	ISO 3834, ISO 15614, ASME B31.x, ASME IX, API 1104
Pipe manufacture	ISO 3183, API 5L
Welder qualification	ISO 9606, ASME IX, API 1104