16.6 The Basic Elements of Welding Symbols
Cameron Kjeldgaard
If an engineer or designer would like welding to be carried out on a project they need a way to communicate that to the people (you) who are doing the welding. This information is often communicated via the blueprint. Welding can require a lot of specific information, for example: the type and size of the weld, the required weld groove preparation, the extent and location of the weld. Welding symbols provide a space-saving method for conveying all this, and more, information. There is a certain amount of explanation required to interpret a welding symbol properly. It is highly recommended that you read chapter 15, Weld Identification, before proceeding. The information provided in chapter 15 will be necessary to understand what types of welds and weld dimensions that will be discussed.
The Reference line, Arrow and Tail
The arrow serves the same function as a leader line. The arrow points to the weld joint, or surface, where the information on the weld symbol should be applied.
The reference line is where the bulk of information in the welding symbol is presented. It is important to note that the arrow may extend from either the left or right side of the reference line, it may also point to a place above or below the reference line. No matter the orientation or direction of the arrow the information on the reference line is always shown and read in the same order from left to right and top to bottom. This means that the pictogram of the weld is always in the center, while the size of the weld is always to the left, and length of the weld always to the right.
Whether the information is on the top or bottom of the reference line also has special significance. The arrow of the welding symbol will point to a weld joint, most weld joints have two sides to them. Information below the reference line refers to the arrow side of the joint, that is to the side of the joint the arrow is pointing at. Information above the reference line applies to the other side of the joint, opposite the side the arrow is pointing at.
The tail is always opposite from the arrow on the reference line. The tail is not always necessary, but serves an important purpose. The tail serves as a catch-all for any information that may need to be written out regarding the weld. If a specific weld process is required a note reading “GMAW”, “SMAW”, or “FCAW” may be placed here. Similarly if the weld in the symbol is to be applied multiple places a note reading “3 side” or “3 places” would be written. In some cases a single weld symbol may be used for many weld joints, the word “typical” or abbreviation “TYP” would be written in the tail.
Pictorial Elements of The Weld Symbol
There are a number of symbols, or small pictograms, used in welding symbols. Symbols that appear on the reference line indicate a a fillet weld or specific type of groove weld. For more information on fillet and groove welds see Chapter 15. These symbols i