Metalsan produces welded structures conforming to Uni EN 1090 up to execution class EXC4.

FAQ

• What is the difference between execution class EXC3 and EXC4?
  Execution classes from EXC1 to EXC4 are defined by UNI EN 1090-2 and establish, for each level, the requirements for welding, inspection, traceability and documentation. The applicable class for a structure is determined by combining three parameters: the consequence class CC1–CC3 according to UNI EN 1990, the service category SC1–SC2 (SC2 for structures subject to fatigue or located in seismic areas), and the production category PC1–PC2.
  
  On this basis, most infrastructure projects managed by Metalsan, such as road and railway bridges, large roofing structures and public buildings, fall under EXC3. EXC4 is reserved for structures where the consequences of failure are exceptional and is specified on a case-by-case basis by the designer or in the project specifications.
  
  Moving from EXC3 to EXC4, the requirements become more stringent in three key areas:
  

  • weld acceptance criteria: level B according to UNI EN ISO 5817 for EXC3, and level B+ (level B with additional requirements) for EXC4;
  • extent of non-destructive testing: for transverse butt joints under tension, this increases from 20% to 100%;
  • coordination of welding activities: comprehensive technical knowledge in accordance with UNI EN ISO 14731, in addition to UNI EN ISO 3834-2 certification.

  Metalsan is certified to operate up to EXC4, the most stringent execution class provided for by the standard.
• What non-destructive testing do you carry out on welded steel structures?
  The UNI EN 1090-2 standard establishes the minimum testing percentages based on the execution class and the type of joint. On this basis, we prepare a dedicated inspection plan for each project, carried out by personnel certified to UNI EN ISO 9712 Level II:
  
  

  • Visual Testing (VT): 100% of all welds, for every execution class.
  • Magnetic Particle Testing (MT) or, for non-ferromagnetic materials, Penetrant Testing (PT): used to detect surface and near-surface defects, also applied to fillet welds.
  • Ultrasonic Testing (UT): used to detect internal defects in full-penetration joints, with increasing coverage from EXC2 to EXC4, up to 100% testing.
  • Radiographic Testing (RT): used as an alternative to UT on butt joints, where the thickness and geometry allow.

  
  Acceptance criteria are those specified in UNI EN ISO 5817 corresponding to the execution class of the structure. Each inspection is documented in reports that are included in the project dossier.
• How do you ensure the traceability of the steel used in your projects?
  Each delivery is accompanied by the 3.1 inspection certificate in accordance with UNI EN 10204, as required by UNI EN 1090-2 from execution class EXC2 onwards; for EXC3 and EXC4, traceability is maintained continuously throughout all stages of fabrication. CE marking of the finished component is issued in accordance with UNI EN 1090-1, the harmonised standard under Regulation (EU) No. 305/2011 (CPR).
  Physical identification of the components is carried out using low-impact marking or non-intrusive systems: on fatigue-stressed members, traditional stamping is excluded, as the indentation may act as a crack initiation point.