It is not uncommon for welding symbols to be included in the designs that architects and drafters send. The purpose is to guarantee that the welder understands how the architect wants the welding to be performed. These instructions will include:
- The Type of Weld Being Used
- The Size of the Weld
- How Many Similar Welds Will Be Performed
- Any Job Specific Instructions
When a person is beginning to learn how to weld, being asked to look at blueprints can be overwhelming. Learning how to read the blueprints is an essential part of completing your job.
Reading Welding Blueprints 101
The first step in reading welding symbols is to look at the back of the symbol. It should have an abbreviation or symbol that describes the type of welding process you should use.
The symbol or abbreviation will be found in between the two lines that enclose the reference line.
Once you have identified the symbol, then use the reference line as a guide to tell you where you should do the welding. Sometimes the symbol is at the reference line, and in other instances it will go beyond or branch out as indicated by multiple arrows. These arrows show you where you need to perform different welding tasks.
Understanding Welding Symbols
Welding symbols have a specific structure. Every welding symbol is going to have an arrow. This points to the location where you need to do the weld.
The arrow is connected to a leader line. The leader line in turn intersects with the reference line that runs horizontally.
There is a tail at the opposite end of the arrow on the reference line. The tail may have forks that point off in different directions. This is where you will see specialized instructions.
When you look at the middle of the reference line, you will either see a geometric shape or parallel lines. This indicates the type of weld you should do on the metal.
It is important to not confuse the weld symbol, which indicates the type of weld to be done, with the overall welding symbol that gives you the complete instructions for the welding job.
When you look at the weld symbol, pay close attention to its placement. If the weld symbol is underneath the reference line, it means that the weld must be performed on the arrow side of the joint. However, if the weld symbol is above the reference line, then the weld should be made on the opposite side of the joint from where the arrow is pointing.
If you see the weld symbol on both sides of the reference line, it means that you will need to weld both sides of the joints.
Various welding symbols have been created to represent the different types of welds you will need to use. For example, a V-shaped symbol indicates a V weld. “||” would indicate a square weld, and so forth.
It can take some time to memorize the different symbols. There’s nothing wrong with printing a cheat sheet that contains the symbols so you can reference them to make sure that you are making the correct type of weld.
Dimensions and Angles
It is not surprising that dimensions and angles are a large part of welding blueprints. Welding blueprints have succinct ways of communicating width, depth, as well as the opening and length of a weld.
For the most part, the width or diameter of the weld is written on the left of the weld symbol and will be written as a fraction in inches.
If the weld size is written above the reference line, it applies to the joint opposite of where the arrow is. If it is written below the reference line, then it should apply to the side of the joint where the arrow points.
Welding symbols can also indicate if the weld should mirror each other or if they should be offset.
The angle of a weld, its root opening, or root face dimension will be included in the welding symbol.
As we mentioned in the outset, the welding symbol may have an optional tail on the side opposite of the arrow. This space is used to convey details that are not part of the normal parameters for a weld.
As an example, the engineer may want the welder to use stick welding in a particular area. And so this will be specified in the optional tail section.
The Challenge of Reading Blueprints
Reading blueprints can be a challenge. It can be a confusing task. With time and with experience, reading blueprints will become second nature to you. The longer you read them, the easier it’s going to be for you to understand them.
Welder blueprints contain a lot of information, and so you should never rush while you read them. It is better to be safe and make the right type of weld in the right location, then to make the wrong type of weld in the wrong location and ruin an entire project.
Learning how to weld is an amazing skill. But its value is limited if you do not understand instructions that are given to you. Understanding a welding blueprint is what will take you from being an average welder and turn you into someone who can make a living at the job.
You have to practice reading and visualizing all of the components that are on paper. Make it your goal to learn something new every week, and do not be afraid to ask questions. In this way, you will watch your welding skills grow exponentially.