General Requirements, Design of Welded Connections, and Detailing
Scope and responsibilities (Clause 1)
Clause 1 fixes the code's boundaries: which base metals are approved, what the Engineer must approve in writing, and how drawings, specifications, and erection documents interact. Know that the Engineer owns design decisions and any departure from the code, while the fabricator owns execution to an approved WPS.
Design of welded connections (Clause 2)
Core concepts: joint types (CJP, PJP, fillet, flare groove, plug/slot), effective weld area = effective length × effective throat, and the separation of required from available strength. For equal-leg fillets the effective throat is 0.707 × leg; skew reduces it, and the annexes give effective throats for flare-bevel and flare-V grooves (a full-fusion flare bevel is commonly taken as 5/16 R). Minimum fillet size is keyed to the thickness of the thicker part joined; maximum size along a free edge is limited (thickness for material under 1/4 in, otherwise t − 1/16 in unless the drawing justifies full size). Minimum length of a fillet weld is four times its size.
Question traps
- Using the thinner part when looking up minimum fillet size.
- Treating a PJP as a CJP, or assuming a prequalified detail covers any root opening, thickness, or position.
- Ignoring weld access, backing, or eccentricity in lap and skewed T-joints.
Worked example
A 3/4 in thick T-joint is detailed with a 3/16 in fillet. The thicker part is 3/4 in, which requires a minimum 1/4 in fillet, so the detail is not code-compliant even though 3/16 in would be acceptable on 1/2 in material. Check minimum size before checking strength.