How to Read a Welding Blueprint

Read the reference line. The reference line will point to the weld, and will always be in the shape of an arrow. The welding blueprint will have various reference lines pointing to the location of where a weld goes on the object. You can find the reference lines on the welding blueprint by looking for arrows near the joints of the item on the welding plan.

Read the size and length of the weld. The size and length of the weld will be the two numbers indicated on the reference line. The first number will always provide the size of the weld and the second number will be the length of the weld. If there is a hyphen after the length number then it is the pitch for the weld.

Read the contour requirement. It will show the intended shape of the finished weld. The symbol for contour requirement is an upside down "V" symbol. The important symbol is the one after the upside down "V" that indicates the type of contour required. Expect to see lines and letters, depending on the contour required. Read the "Reference Table" on the plan that indicates what the symbol means; it is usually located on the bottom right of the plan. If your plan does not have a reference table, see Resources for a list of common welding plan symbols and their meanings.