Steel Structure Inspection

In accordance with EN 1090-2 (Section 5) and NTC 2018 (Chapter 11.3.4), all structural steel products must be identifiable and traceable. Materials must comply with EN 10025 (hot-rolled), EN 10210 or EN 10219 (hollow sections) and be accompanied by inspection certificates 3.1 or 3.2 per EN 10204. The fabrication workshop must hold the declaration of activity as a transformation centre per NTC 2018 Chapter 11.3.1.7.

1. Verify material test certificates (EN 10204 type 3.1 or 3.2) for each steel batch

2. Check CE marking of elements per EN 1090-1 and Declaration of Performance (DoP)

3. Verify that steel grade (e.g. S235, S275, S355) matches design specifications

4. Check transformation centre attestation and compliance with NTC 2018 Chapter 11.3.1.7

5. Verify material traceability from steel mill to the installed finished element on site

6. Check that any substitute products have been approved by the designer

- Test certificates missing or not matching the materials actually used

- CE marking absent or illegible on structural elements

- Use of steel with grade different from design without approval

- Transformation centre lacking the ministerial attestation required by NTC 2018

- Traceability lost during workshop fabrication phases

In accordance with EN 1090-2 (Section 8) and EN 1993-1-8, bolted connections must be made with bolts conforming to the specified strength classes (EN 14399 for preloaded high-strength bolts, EN 15048 for non-preloaded bolts). NTC 2018 (Chapter 4.2.8) requires connections to be executed per design specifications and checked on site.

1. Verify bolt strength class (e.g. 8.8, 10.9) and compliance with certificates and design specifications

2. Check hole diameter, edge distances and spacing per EN 1993-1-8 Table 3.3

3. For preloaded bolts (EN 14399), verify tightening torque with calibrated torque wrench using the specified method (torque, nut rotation, combined or DTI)

4. Verify that all contact surfaces are prepared to the required friction class (EN 1090-2 Section 8.4)

5. Check that every bolt is present, correctly tightened and with washer in position

6. Verify tightening sequence for multi-bolt connections

- Bolts not tightened to the prescribed torque or without documented control

- Contact surfaces not prepared for friction connections

- Elongated or misaligned holes reducing joint capacity

- Bolts of incorrect class relative to design

- Missing washer under the rotated element during tightening

In accordance with EN 1090-2 (Section 7), EN ISO 5817 and NTC 2018 (Chapter 4.2.8 and Chapter 11.3.4.5), structural welds must be performed by qualified welders (EN ISO 9606-1) using qualified procedures (WPS/WPQR per EN ISO 15614-1). Weld quality levels must comply with EN ISO 5817, level B or C as specified in the design.

1. Verify welder qualifications (EN ISO 9606-1) and certificate validity

2. Check welding procedure specifications (WPS) and qualification records (WPQR)

3. Perform 100% visual inspection (VT) of welds per EN ISO 17637

4. Verify execution of non-destructive testing (NDT) per inspection plan: ultrasonics (UT - EN ISO 17640), magnetic particle (MT - EN ISO 17638), dye penetrant (PT - EN ISO 3452-1) or radiography (RT - EN ISO 17636)

5. Check weld dimensions (throat, length) against execution drawings

6. Verify inspection documentation and compliance with acceptance levels

- Welders without valid qualification for the joint type and welding position

- WPS missing or not conforming to procedure qualification

- Weld defects: slag inclusions, porosity, lack of penetration, cracks

- NDT not performed or with insufficient coverage

- Inadequate edge preparation or unfavourable environmental conditions (humidity, low temperature)

In accordance with EN 1090-2 (Section 10), EN ISO 12944 and NTC 2018, steel structures must be protected against corrosion based on the environmental corrosivity category (C1-C5, CX per EN ISO 12944-2). The protective system (hot-dip galvanising EN ISO 1461, painting, metallising) must be specified in the design and match the required durability.

1. Verify the environmental corrosivity category specified in the design per EN ISO 12944-2

2. Check surface preparation (blast cleaning grade Sa 2 1/2 per EN ISO 8501-1) before coating application

3. Measure dry film thickness (DFT) with thickness gauge per EN ISO 2808 and verify compliance with minimum values

4. For hot-dip galvanising, verify minimum coating thickness per EN ISO 1461

5. Check coating integrity at site weld zones, holes and cut edges

6. Verify that coating repairs on areas damaged during transport or erection are carried out with compatible products

- Insufficient surface preparation with residual rust or contaminants

- Coating thickness below specified minimums, especially on edges and corners

- Coating damage during transport and erection not repaired

- Site weld zones left unprotected after execution

- Protective system not adequate for the site corrosivity category