Introduction on how to read welding symbols

First, what are the welding symbols? What is their purpose? How can it help welding inspectors?

Welding symbols provide a system for placing complete welding information on drawings. These are not just for welding inspectors but other welding personnel such as designers, supervisors and engineers as well.

Welding symbols quickly provide information from the designer to the workmen regarding the welding parameters needed.

Welding symbol vs. weld symbol

Let us first get something out of the way, welding symbol and weld symbol differ and AWS makes a clear distinction between those two.

Weld symbols identifies each type of weld and is only the part of the total information indicated in the welding symbol. Weld symbols are drawn above and below the reference line of the welding symbol as seen below.

Here are the types of weld that weld symbols may represent and be indicated on top or bottom of the reference line of the welding symbol. Note that the dashed line in the table below represents the reference line.

Welding symbol, in the meantime, contains the totality of the information including the weld type required, size, location and even the testing needed can be indicated in the welding symbol.

Welding symbol elements

You may have seen in the drawings these welding symbols but what are their parts?

The following elements are as follows, note that the only required element to be reflected in the welding symbol are the reference line and the arrow. All others are not required (note that for CWI exam takers this question is often asked as well). But the three most basic parts or elements of the welding symbol are the reference line, arrow and the tail.

• Reference Line - this is always drawn horizontally and is used to apply the weld symbols and other data. Sometimes, multiple reference lines can also be done.
• Arrow - directs the reference line to the welding joint or area to be welded. It may be shown with multiple arrows too.
• Tail - contains the specification or process involved in welding. You may indicate the welding or cutting process used, or any other supplementary information needed such as codes, drawing notes, and sometimes to avoid repetition of the welding symbol, the abbreviation TYP is indicated.
• Basic weld symbol - the weld symbols that are specified in the above table. These weld symbols can often be combined with each other.
• Dimensions and other data - the dimensions and other data depends upon the type of weld specified such as root opening, groove angle, length of weld, pitch, depth of bevel etc.
• Supplementary symbols - this are used in connection with the weld symbol and can indicate extent of welding, and material included in the preparation of the weld joint. The supplementary symbols are indicated in the below table.
• Finish symbols - these symbols specify the finished face of the weld if it should appear flat, convex, concave, etc. Certain mechanical finish methods may also be included such as chipping, grinding, hammering, machining, rolling or others tagged as unspecified. The figure below provides an example of how to show these.
• Specification, process or other reference

Weld symbol location and placement

There is a significance where the weld symbol is placed above or below the reference line and it is shown below.

If the weld symbol is below the reference line meaning the pointed weld of the arrow should be on the arrow side of the joint. But if the weld symbol is placed above the reference line, then the weld being pointed by the arrow must be on the other side of the joint.

For example, the weld cross section below has a fillet weld, you can see that the arrow is pointing at the same side of the joint hence, the weld symbol must be placed below the reference line.

If for example, the welds are made on both sides of the joint, then the weld symbol must be placed above AND below the reference line as shown.

What if there are multiple or a combination of welds in a joint? I have mentioned above that this can be done. Let me show an example below.

As you may see here, the other side of the joint (top of the reference line) has a combination of fillet and single bevel-groove weld, you can tell the single bevel because of the preparation made on the other side of the joint, shaped like a half-open vee and on top of it is a fillet weld.

On the arrow side of the joint, there is only a fillet weld as you can see.

Use of the tail

Tail is not an essential part of the welding symbol but can be used as a powerful tool in including process, specification, procedure, drawing reference, even testing procedure that needs to be followed.

Some examples are as follows (demonstrated in the images below):

• Use of a specific welding process
• Indicating notes in the drawing
• Use of typical notes

If you want to learn this in a video format, here is the youtube link for you!

Learning welding symbols is an integral part of being a welding inspector. If you want to learn more, you can sign-up on my FREE udemy course in this link. You can check out the rest of my free content in my youtube channel below!