EN 15614 is a crucial European standard series titled “Specification and qualification of welding procedures for metallic materials – Welding procedure test.” The standard establishes the requirements for welding procedure qualification tests, ensuring that welding processes consistently produce joints meeting specified quality and performance criteria. The EN 15614 series consists of multiple parts, with Part 1 (EN 15614-1) being the most widely referenced, covering arc and gas welding of steels and arc welding of nickel and nickel alloys.
The standard was developed to harmonize welding procedure qualification across Europe, replacing various national standards. It specifies how welding procedures must be qualified through testing, with the same welding equipment used for both qualification and production welding. EN 15614 is particularly critical for industries where weld integrity is paramount, such as pressure vessel fabrication, pipeline construction, and structural steelwork.
Key aspects of EN 15614 include:
- Mandatory qualification testing for welding procedures before production begins
- Standardized test methods for mechanical and metallurgical properties
- Classification system for welding processes, materials, and joint configurations
- Documentation requirements for Welding Procedure Specifications (WPS) and Procedure Qualification Records (PQR)
- Validity ranges for qualified procedures (thickness, diameter, etc.)
The standard is frequently referenced alongside other welding standards like EN ISO 15609-1 (for WPS requirements) and EN ISO 15607 (general principles for qualification)
Products Applicable to EN 15614
EN 15614 applies to a wide range of welded products across multiple industries, particularly where weld quality and structural integrity are critical:
- Pressure Equipment: Including boilers, pressure vessels, and heat exchangers where welding must meet strict integrity requirements
- Pipeline Systems: Especially for critical applications like hydrogen pipelines where additional hardness criteria apply
- Structural Steelwork: For buildings, bridges, and offshore structures using steels like S460M (as specified in BS EN 10025)
- Shipbuilding and Offshore Structures: Heavy steel fabrication where procedures must account for thick sections (up to 100mm in some cases)
- Transportation Equipment: Welding of high-strength steels like S700MC used in vehicle structures
- Industrial Machinery: Components requiring high-integrity welds in materials ranging from carbon steels to stainless steels
The standard is particularly relevant for products made from:
- Carbon and carbon-manganese steels
- Low alloy steels
- Stainless steels
- Nickel and nickel alloys
Examples from research include qualification of welding procedures for L415ME steel pipes in hydrogen service and heavy structural steels in shipbuilding applications
Testing Methods for EN 15614
EN 15614 specifies comprehensive testing methods to qualify welding procedures, ensuring they produce joints with the required mechanical and metallurgical properties:
- Mechanical Testing:
- Tensile Testing: To verify weld metal strength, typically requiring failure in the base metal rather than the weld
- Bend Testing: Both face and root bends (180° with 40mm former diameter) to assess ductility and lack of defects
- Impact Testing: Charpy V-notch tests at specified temperatures to evaluate toughness, particularly important for low-temperature applications
- Hardness Testing:
- Vickers or Rockwell hardness surveys across weld, HAZ, and base metal
- Critical for applications with hardness limits (e.g., hydrogen service pipelines)
- Macroscopic Examination:
- Evaluation of weld bead profile, penetration, and lack of defects
- Sectioning and etching to reveal weld structure and HAZ characteristics
- Non-Destructive Testing (NDT):
- Radiographic testing (RT) using X-rays to detect internal defects
- Ultrasonic testing (UT) for thicker sections.
- Penetrant or magnetic particle testing for surface defects.
- Metallurgical Examination:
- Microstructure analysis of weld metal and HAZ
- Detection of undesirable phases or microstructural features
The standard specifies different testing levels (e.g., Level 2 in EN ISO 15614-1 requires specific mechanical tests per clause 7.3 & 7.4, testing must be performed on test coupons that represent the actual production welds in terms of joint design, material, and welding parameters.
Important Issues to Note for EN 15614 Compliance
When implementing EN 15614 for welding procedure qualification, several critical issues require careful attention:
- Documentation Requirements:
- Complete WPS (Welding Procedure Specification) must be prepared before qualification
- PQR (Procedure Qualification Record) must document all test results accurately
- Both documents must be properly reviewed and approved
- Parameter Control:
- Production welding must use the same parameters (within qualified ranges) as procedure qualification
- Essential variables (current, voltage, travel speed, heat input) must be carefully monitored
- Material Considerations:
- Base metal and filler metal combinations must be properly qualified
- Special requirements apply for hydrogen service (e.g., hardness limits)
- Preheat and Post-Weld Heat Treatment (PWHT):
- Must be properly specified and controlled, especially for thick sections (>20mm often requiring preheat)
- PWHT parameters can significantly affect mechanical properties
- Testing Limitations:
- Qualification tests have validity limits (thickness ranges, diameter ranges, etc.)
- Out-of-position welding may require additional qualification
- Personnel Competency:
- Welders must be qualified separately (EN ISO 9606 or equivalent)
- Testing personnel must be competent to perform and evaluate tests
- Industry-Specific Requirements:
- Some industries (nuclear, aerospace) may have additional requirements beyond EN 15614
- National regulations may impose supplementary requirements
- Maintenance of Records:
- Qualification records must be maintained for the life of the product
- Changes to procedures may require re-qualification
The standard emphasizes that welding procedure qualification is not a one-time activity but an ongoing process requiring careful control of all variables that could affect weld quality. Proper implementation requires understanding both the technical requirements of the standard and the practical considerations of production welding
