Welding processes
Qualification of welding processes
Welding processes are essential permanent joining techniques in almost every sector of the manufacturing industry, from automotive to construction, energy to aerospace. A well-executed welding process ensures the structural integrity and safety of the final product. However, it is crucial to distinguish between the concept of welding procedures (i.e., the specific technique used to join materials, such as TIG, MIG/MAG, or MMA) and the qualification of the welding process. While the former defines “how” one welds, qualification is the formal process of documentation and verification that ensures that a given process, applied under specific conditions, consistently produces joints with the required mechanical and metallurgical properties.
The main types of welding processes
Why qualify a welding process
Qualifying welding processes is not only a regulatory requirement in many industries (such as metal structure construction or pressure equipment manufacturing), but a real competitive advantage for the company.
By demonstrating a certified welding process, the company ensures quality and reliability of each welded joint. Through formal documentation of the process, the company demonstrates that it operates with controlled and repeatable parameters, dramatically reducing the risk of defects, rejects, and ultimately costly nonconformities or structural failures in the field.
Having qualified welding processes then makes it easier for companies to enter regulated markets and access government contracts. Often, certification of welding processes, as well as other welding certifications (personnel or system) is a prerequisite for participation in tenders.
Standardization of welding procedures reduces variability, improving efficiency and minimizing costs associated with rework and more complex nondestructive testing, ensuring optimization of production costs. Finally, documenting the proper execution of welding processes protects the company in terms of liability, demonstrating due diligence and compliance with safety standards for the final product.
When welding process qualification is mandatory
Welding process qualification is mandatory in all sectors where a failure of the welded joint may pose significant risks to public safety, the environment or critical operation. The main sectors that require welding process certification are:
- Metal Construction and Structures: EN 1090 (for steel and aluminum load-bearing structures) mandates qualification of welding procedures as a prerequisite for CE Marking.
- Pressure Equipment: Directives such as the Pressure Equipment Directive (PED) and specific standards (e.g., EN ISO 15614) require certification for all vessels, tanks and piping that operate under pressure.
- Oil&Gas, Railroad, and Aerospace are industries with stringent standards, so welding process qualification is often a necessary condition for operation
Often, while not required by law, the qualification of welding procedures is required by tender specifications or to meet corporate quality standards, such as those required by ISO 3834.
WPS and WPQR: what they are and differences
WPS
WPQR
The WPQR (Welding Procedure Qualification Report), on the other hand, is the objective, certified proof that that “recipe” (the WPS) works. The WPQR is the report issued by a third-party body (or a qualified welding inspector) after testing a welded joint performed following the WPS directions. If destructive testing (such as tensile and bend testing) and nondestructive testing are successful, the WPQR certifies its validity and defines the scope in which that specific WPS can be used.
In summary, the WPS tells how to weld and is used in production, while the WPQR proves that the procedure produces valid joints and is its certifying document. A company must have a valid WPQR in order to legally use the relevant WPS in all its welding procedures.
How welding process qualification works
Welding process qualification is a structured process involving several steps. First, the applicant company prepares the WPS it intends to have qualified and sends it to the certifying agency. Along with the WPS, the applicant company also sends a welded specimen under the supervision of an inspector, which is subjected to nondestructive and destructive testing. After the tests are passed, the WPQR is issued.
Preparation of WPS
The Welding Procedure Specification ( WPS ) is the basic document and essential starting point for the entire welding process qualification process. Before welding the test specimen, the company develops a pWPS (preliminary WPS), which is a detailed operating hypothesis of how the joint will be made.
This technical “recipe” collects all the basic welding parameters that, if followed, should ensure a quality joint. The parameters include:
- Type of welding process (e.g. 135 – MIG/MAG).
- Basic materials (type of steel or alloy) and filler material.
- Joint geometry and welded thicknesses.
- Electrical (current, voltage) and mechanical (welding speed, heat input) parameters.
- Shielding gas and welding position.
The WPS is the basis for any qualification because it sets the limits within which the welding procedure is tested. The final validity of the WPQR will always be linked to the parameters specified in this documentation.
Sample execution and testing
Once the preliminary WPS (pWPS) has been defined, the next step in the welding process qualification path is the execution of the welded sample or specimen. This test joint is welded in the presence of a qualified welding inspector, following the parameters established in the pWPS.
The welded specimen undergoes nondestructive inspection and destructive testing to demonstrate that the welding procedure has produced a quality joint with the required mechanical properties.
Non-Destructive Testing (NDT or CND): These tests check for surface or internal defects (such as cracks or inclusions) without altering the integrity of the joint. Common methods include visual inspection, liquid penetrant, magnetoscopy, and, most importantly, radiographic or ultrasonic inspection for internal inspection.
Destructive Testing: At this stage, the specimen is sectioned and physically tested to measure its mechanical properties. Typical tests include the tensile test, to measure the joint’s resistance to fracture; bend tests, to check its ductility; resilience (or Charpy) test, to measure its impact strength at certain temperatures; hardness tests; andmacrographic examination to analyze its internal structure.
WPQR issuance and validity
If all nondestructive inspections and destructive tests on the welded specimen are successful and the results are in line with applicable regulatory requirements (e.g., EN ISO 15614), the welding inspector or certifying agency will prepare and sign theWelding Procedure Qualification Record ( WPQR ).
The WPQR then certifies the effectiveness of that specific welding procedure and defines its validity range, i.e., all operational limits within which the corresponding WPS can be used in production. The validity criteria include:
- Allowable types of joints;
- Base and input materials covered;
- Maximum and minimum thicknesses and diameters that can be welded;
- Approved welding positions.
The issuance of the WPQR means that the company can use its welding procedures in a safe, documented and compliant manner, ensuring the quality of the joint in all work within the certified scope.
Duration of welding process certification
The ISO 15614 reference standard states that the welding process qualification remains valid and does not expire unless changes are made to the process itself or it is not applied in production for a long time.
Sideius issues qualifications for your welding processes according to ISO 15614 or EN 1090
How we take you to certification
Sideius, through the Valor brand, operates as a Certification Body accredited by Accredia according to UNI EN ISO 17065 for the qualification of welding procedures WPS (Welding Procedure Specification) and WPQR (Welding Procedure Qualification Record). Activities are carried out in accordance with applicable standards and follow a formal process that ensures impartiality, traceability and uniformity of evaluation. The Certification Body appoints a qualified inspector to evaluate the welding procedure according to the required standards. After some preliminary checks, samples are made based on the WPS provided by the applicant company and approved by Sideius. The activities can be carried out at the company’s premises, at Sideius, or in facilities adequately equipped from a technical and safety point of view.
Destructive and non-destructive tests are carried out at Sideius laboratories (through the TEC Eurolab brand) accredited according to ISO/IEC 17025.
At the end of the verifications, if the results comply with the requirements, the inspector draws up the qualification documentation, which is submitted to the internal approval process. In case of a positive outcome, they are issued:
- the WPQR qualification certificate
- the approved WPS
- the test reports
- Documentation of the materials used (if available)
- Any information on nonconformities found and repeated testing.
In addition to welding process certification, the Sideius Certification Body, through the Valor brand, can certify welding personnel (welder licenses) and the welding quality management system (ISO 3834), completing the framework of certifications in welding.
FAQ - Welding Process Certification
What is meant by the welding process?
The welding process is the specific technology used to weld two metals. Some examples are TIG, MIG/MAG, MMA.
What is the difference between WPS and WPQR?
The WPS is the detailed “recipe” (the operating instructions) that specifies how to perform a weld (materials, currents, speeds, gases, etc.). The WPQR, on the other hand, is the official document that certifies and authorizes the use of the WPS
How long is the qualification of a welding process?
Once qualified and if it is unchanged, the certification of the welding process does not expire
In what areas is it mandatory?
Qualification is mandatory in all sectors where joint failure would pose serious risks to safety or structural integrity. The main sectors are:
- Metal Construction and Structures (e.g., building, bridges – EN 1090 standard).
- Pressure Equipment (e.g., tanks, piping – PED Directive).
- High Responsibility Sectors (e.g., oil & gas, rail, aerospace).
What regulations govern the qualification of welding procedures?
The main standards are those of the UNI EN ISO 15614 series, particularly UNI EN ISO 15614-1 (for arc welding on steels), which define the requirements for testing and issuance of WPQR. Other related standards are ISO 3834 (Welding Quality Management System) and EN 1090 (structures).
Is the welder's license sufficient without the process qualification?
No, the welder’s license (UNI EN ISO 9606) attests to the operator’s manual skill. The process qualification (WPQR/WPS) certifies that the process used is technically sound and produces joints with the required properties. Both are required: the qualified operator must weld following a qualified process.
Do you want to certify your welding processes?
Contact us for more information or to start the qualification process now