Interpretation of Welding Drawings, Symbols and Specifications
This domain tests fluency with AWS A2.4 symbols and the drawings and specifications that carry them, plus the ability to convert a symbol into a buildable joint. Expect a symbol to be described in words and a question on how to read it.
The symbol framework
Reference line carries the weld; arrow points to the joint; tail holds the process, WPS number or reference document; size goes to the left of the symbol; length and pitch go to the right; a circle at the elbow means weld all around; a flag means field weld. Supplementary symbols cover contour (flush, convex, concave) and finish.
Fillet versus groove
A fillet size is the leg length unless marked with a throat dimension or a triangle note. Groove symbols show the preparation shape; the included angle, root face and root gap are usually given in the detail view or the WPS, not on the symbol. PJP and CJP designations change the inspection and NDT requirement.
Specifications
The general notes name the code (for example AWS D1.1 for structural steel), the filler classification (E71T-1C or E71T-1M), preheat, interpass limits and acceptance criteria. The tail is where the WPS number sits - ignore it and you lose the parameters.
Worked example
A symbol shows a fillet on the arrow side, size 6, with "50-150" to the right, an all-around circle at the elbow, and a tail reading WPS-12. Read it: 6 mm leg fillets on the arrow side only, in 50 mm long segments spaced 150 mm centre to centre (100 mm gaps), continuous around the member at that junction, welded per WPS-12. The number of segments follows from the member perimeter; the pitch is centre-to-centre, not gap.
Traps that cost marks
Reading fillet size as throat. Mixing arrow side and other side. Treating pitch as gap length. Missing the all-around circle or field flag. Ignoring the tail and welding to a default parameter set.