How to Read a WPS: Welding Procedure Specification Explained
How to read a Welding Procedure Specification. Essential variables, PQR relationship, what welders need to know, and what happens when you deviate from the WPS.
Welding Symbols Chart & Guide
AWS welding symbols explained: reference line, arrow side vs other side, groove and fillet symbols, supplementary symbols, tail notations, and how to read a welding symbol on a blueprint.
Welding symbols are the language between the engineer and the welder. Every welded joint on a blueprint gets a symbol that specifies exactly what type of weld, what size, which side, and any special requirements. Reading symbols correctly means you produce the joint the designer intended. Misreading them means rework or rejected welds.
The reference line is the foundation of every welding symbol. It’s the horizontal line that carries all the information. The arrow extends from one end and points to the joint being welded. Below the reference line is the “arrow side” (the surface the arrow touches). Above the reference line is the “other side” (the opposite surface). This arrow-side/other-side system tells you exactly where to put the weld.
Groove weld symbols sit on the reference line and show the cross-section shape: V, bevel, J, U, flare-V, or flare-bevel. A V-symbol below the line means a V-groove on the arrow side. Numbers indicate groove angle, root opening, and depth of penetration. The depth of groove and the effective throat are placed to the left of the symbol.
Fillet weld symbols use a right triangle shape. The number to the left indicates leg size. A 1/4 inch fillet weld symbol means both legs are 1/4 inch. Unequal legs get two numbers. Length and pitch (spacing for intermittent fillets) go to the right of the symbol: “2-5” means 2-inch-long welds spaced 5 inches on center.
Supplementary symbols add detail. A circle at the arrow/reference line junction means “weld all around.” A flag means “field weld” (done on-site, not in the shop). A convex or concave contour symbol specifies the finished weld profile. The melt-through symbol (a filled circle on the other side) indicates complete joint penetration is required on a weld made from one side.
The tail, if present, contains references to welding procedures (WPS numbers), specifications, or process designations (GMAW, GTAW, SMAW). No tail means no special instructions beyond the symbol itself.
The guides below cover each symbol type with examples, common blueprint reading scenarios, and practice exercises.
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Welding Symbol Chart: AWS A2.4 Reference Guide
Printable welding symbol reference chart. AWS A2.4 standard symbols, arrow side vs other side, supplementary symbols, finish symbols, and tail references.