Welding symbols are used on blueprints and drawings to show where and how the weld should be placed. Welders that fabricate or work with drawings must be able to interpret the welding symbols to prepare the joint and apply a weld that has the required strength and soundness.
There are three basic types of butt-welding, and each is chosen based on the thickness of the objects being joined. For thin sheets of metal or plastic, a square weld joint can be used. In this instance, the edges of the objects form 90-degree angles to one another, and can be butted together like two building blocks. This is the simplest and most economical type of butt-welding joint.
The groove/butt weld symbols are used to provide information for preparing and welding the groove or butt; however, they cannot always show every intended operation and often notes or specifications are used on the drawing. The welder should read the entire drawing before making a weld to avoid expensive rework.