Steel Structure Inspection

According to EN 1090-2 Section 5, all structural steel must have CE marking and be traceable to mill certificates (EN 10204 Type 3.1). Steel grades (S235, S275, S355, S460) must match the design specification. Material properties must comply with EN 10025 for hot-rolled products.

1. Check that mill certificates (EN 10204 Type 3.1) are available for all steel elements

2. Confirm CE marking and declaration of performance for each delivery

3. Confirm that steel grade markings on elements match the design (e.g. S355J2)

4. Check material traceability — each piece traceable to its certificate

5. Confirm that substituted materials are of equal or higher grade with design engineer approval

- Mill certificates missing or incomplete

- Steel grade not matching the design specification

- Loss of traceability during fabrication — unidentified offcuts reused

- Incorrect steel sub-grade for the service temperature (e.g. J0 used where J2 is required)

According to EN 1090-2 Section 8, bolted connections must use the correct bolt class (8.8 or 10.9 for structural use per EN ISO 898-1). Preloaded bolts in slip-resistant connections must be tightened according to EN 1090-2 Table 20, using calibrated torque, combined or direct tension methods. Hole tolerances according to EN 1090-2 Table 11.

1. Check that the bolt class (8.8 or 10.9) matches the design — verify head markings

2. Confirm the tightening method for preloaded connections (torque, combined or DTI)

3. Check torque values with a calibrated torque wrench per EN 1090-2 Table 20

4. Inspect hole alignment — no excessive reaming or elongated holes

5. Confirm that washers, nuts and bolts are from the same set (matched assemblies)

- Wrong bolt class installed (e.g. 4.6 instead of 8.8)

- Preloaded bolts under-tightened — slip under service loads

- Holes misaligned, forced with drift pins causing element damage

- Washers missing on oversize or slotted holes

According to EN 1090-2 Section 7 and EN ISO 5817, welds must meet the specified quality level — typically B (stringent) or C (intermediate) for structural connections. Welding procedures must be qualified according to EN ISO 15614-1. Welders must hold valid certificates according to EN ISO 9606-1.

1. Check that welding procedure specifications (WPS) are approved and available

2. Confirm that welder qualification certificates (EN ISO 9606-1) are valid and cover the joint type

3. Visually inspect welds per EN ISO 5817 — check for undercut, porosity, cracks, lack of fusion

4. Confirm that non-destructive testing (NDT) has been carried out per the inspection plan — ultrasonic, magnetic particle or dye penetrant as specified

5. Check weld dimensions (throat thickness, leg length) with weld gauges

- Welds not conforming to quality level B or C per EN ISO 5817

- Lack of fusion or incomplete penetration in full-penetration butt welds

- Lamellar tearing in thick plates with through-thickness loading

- Welding carried out without an approved procedure or by an unqualified welder

According to EN 1090-2 Section 10 and EN ISO 12944, corrosion protection must be appropriate for the corrosivity category (C1–C5, CX). Surface preparation must meet the specified grade per EN ISO 8501-1 (typically Sa 2 1/2 for blast cleaning). The paint system (primer, intermediate, finish) must match the durability requirement (low, medium, high, very high). In Portugal, special attention must be paid to coastal zones (category C4–C5) given the extensive coastline.

1. Check that the corrosivity category matches the environment (e.g. C3 for urban, C5 for marine/industrial)

2. Confirm the surface preparation grade — Sa 2 1/2 is typical for structural steel

3. Measure the dry film thickness (DFT) of each coat — must meet the specification per EN ISO 12944-5

4. Inspect for coating defects: holidays, runs, blistering or untreated areas

5. Check that site connections and welds have been touched up after erection

- Insufficient surface preparation — rust or mill scale beneath the coating

- Coating too thin or too thick (both cause premature failure)

- Site welds and bolted connections left uncoated

- Paint system not suitable for the corrosivity category