Steel Structure Inspection

In accordance with EN 1090-2 Section 5, all structural steel must bear CE marking and be traceable to mill certificates (EN 10204 Type 3.1). Steel grades (S235, S275, S355, S460) must match the structural design. Material properties must comply with EN 10025 for hot-rolled products. In Germany, compliance with DIN EN 1993-1-1/NA must also be observed.

1. Check mill certificates (EN 10204 Type 3.1) for completeness for all steel components

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

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

4. Ensure material traceability — each component must be traceable to its certificate

5. Where materials have been substituted, verify equal or higher grade with designer's approval

- Missing or incomplete mill certificates

- Steel grade does not match the design

- Traceability lost during fabrication — unmarked offcuts reused

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

In accordance with EN 1090-2 Section 8, bolted connections must use the correct bolt grade (8.8 or 10.9 for structural steelwork per EN ISO 898-1). Preloaded bolts in slip-resistant connections must be tightened per EN 1090-2 Table 20 using calibrated torque, combined or direct tension indicator methods. Bolt hole tolerances per EN 1090-2 Table 11.

1. Verify bolt grade (8.8 or 10.9) from head markings against design

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

3. Verify tightening torques with calibrated torque wrench per EN 1090-2 Table 20

4. Check bolt hole alignment — no excessive reaming or slotted holes

5. Ensure washers, nuts and bolts are from the same assembly set

- Incorrect bolt grade installed (e.g. 4.6 instead of 8.8)

- Preloaded bolts not correctly tightened — slip under service loads

- Bolt holes not aligned, forced with drift pins — component damage

- Missing washers at oversize or slotted holes

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

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

2. Check welder qualifications (EN ISO 9606-1) for validity and coverage of connection type

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

4. Verify non-destructive testing (NDT) has been performed per inspection plan — UT, MT or PT as specified

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

- Welds do not achieve 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 loaded in the through-thickness direction

- Welding without approved welding procedure or by unqualified welder

In accordance with EN 1090-2 Section 10 and EN ISO 12944, corrosion protection must match the corrosivity category (C1-C5, CX). Surface preparation must achieve the specified grade per EN ISO 8501-1 (typically Sa 2 1/2 for blast cleaning). The coating system (primer, intermediate coat, topcoat) must correspond to the durability requirement (low, medium, high, very high). Additionally, the DASt Guideline 006 and DIN EN ISO 12944 must be observed.

1. Verify corrosivity category matches the environment (e.g. C3 for urban, C5 for coastal/industrial)

2. Check surface preparation grade — Sa 2 1/2 is standard for structural steelwork

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

4. Inspect coating for defects: pinholes, runs, sags, blistering or uncoated areas

5. Ensure site connections and welds are touch-up coated after erection

- Insufficient surface preparation — rust or mill scale beneath coating

- Coating too thin or too thick (both lead to premature failure)

- Site welds and bolted connections left uncoated

- Incorrect coating system for the corrosivity category