Steel construction and metal fabrication: design rules
Fabricated and erected structural steel: frames, platforms, stairs, railings.
Typical tolerance
Governed by the applicable standard (EN 1090-2 in Europe, AISC and AWS D1.1 in the USA).
Files to send
Engineer's drawings; the shop produces shop drawings and often needs the connection design from the engineer of record.
Common materials
S235, S355 (EN) or A36, A572 (ASTM) structural steel; stainless for visible or corrosive environments.
The rules, with reasons
- Standard and class. State the standard and execution class (EN 1090 execution classes 1–4, or AISC/AWS D1.1) in the request. Why: It decides welder qualification, inspection and paperwork.
- Corrosion protection. Specify paint system, hot-dip galvanizing (ASTM A123) or ISO 12944 class. Why: It sets cost and lead time and affects the design (vent and drain holes).
- Inspection. State the testing of welds and bolts. Why: It is part of the price.
- Transport and site. Check transport limits and site access when you set assembly sizes. Why: Oversize pieces need permits and cost more.
- Responsibility. Clarify who designs connections and who is the engineer of record. Why: Fabricators usually build to drawings, not to a concept.
Before you ask for a quote
- Drawings or sketch with member sizes
- Standard and execution class
- Material grade
- Corrosion protection
- Inspection and certificates
- Site and delivery
Common mistakes
- No standard named
- Forgetting vent holes before galvanizing
- Assuming the fabricator designs the connections
Request a quote Find manufacturers
Typical rules of thumb, not a guarantee. The manufacturer's own design guidelines override them: ask for them and check your design against both before ordering.