Updated: Apr 28
by Jason Becker
When I used to teach at the college, I would often reach out to employers to make sure that my students were learning the skills that they were looking for in potential candidates. One of the topics that always came up was "being able to read welding symbols". With this information in hand, I developed a lecture that would teach students how to interpret welding symbols. The AWS has 2 documents that I highly recommend purchasing for your library. The first one is AWS A2.4 Standard, Brazing, and Nondestructive Examination. The next one is AWS A3.0 Standard Terms and Definitions.
At first glance, welding symbols can be pretty intimidating. But once you learn what everything is, and where each piece goes, they become second nature. Welding symbols are like hieroglyphics from the days of the ancient Egyptians. They tell a story and convey the necessary weld type, size and spacing to meet the engineers requirements to withstand the intended load.
All welding symbols start off at the same place, the reference line. The reference line is a horizontal line and is the basis for all welding symbols. Attached to the reference line is the arrow line. The arrow line points to the area where the weld is to be performed. With the reference line, there are two sides. The top side of the reference line is called the "other-side" and the bottom side is the "arrow-side. This is probably the one spot that trips everyone up the most because the top section is always the opposite side of where the arrow is pointing.
Take this picture for instance. The Backing Bar is on the bottom of the joint configuration, and the Single V-Groove weld is on the top of the plates. But if we look at the symbol, the Single V-Groove weld is on the bottom of the reference line (arrow side) and the backing bar symbol is on the top (other side). If we didn't know any better, we might put the backing bar on top of the weldment and the Single V-Groove on the bottom. But it is actually the opposite. They do take some getting used to and by practicing them with repetition, they will be just as easy to read as any other document.
This video only covers the beginning stages of learning to interpret welding symbols.
In the second video in the series, we do a quick review of Part 1 and then dive into some of the supplementary symbols. Supplementary symbols are additional symbols used to convey additional information about the weldment that aren't necessarily weld symbols. The first one we cover is the weld all the way around symbol which simply tells the welder to make the weld all the way around the object or part. Take an I-beam welded to a base plate for example. We would weld on each side of the I-beam, essentially tracing the profile of the beam with weld metal. This is a very common symbol and is noted by a circle placed where the arrow line meets the reference line on the welding symbol.
Another very common supplementary symbol is the field weld symbol, represented by a flag placed at the intersection of the arrow line and reference line. The flag can be hollow or filled in and be placed in either direction and top or bottom and it means the same thing. The weld will take place somewhere other than its initial place of construction such as in the field or wherever it will be placed for its intended end use.
We also cover the remaining supplementary symbols to include spacers and inserts. In addition, we cover some basic and common groove configurations and how to prepare the weldment to be welded. The symbols are very similar to what the preparation will look like. There are quite a few symbols for bevels so its a good idea to get a copy of the AWS A2.4, a reference chart, or a download of the symbols. If you are not working with symbols all the time, it's easy to forget the placement of the information and what they symbols and supplementary symbols actually mean.
Part 3 is the final installment of the series. We have received a ton of positive comments from our viewers on how helpful the videos were for them. From students using it to take and pass their in-class exams, to welders in the field/shop gaining additional knowledge to use while they are working, and even some engineers and inspectors commented how useful it was for a refresher.
Overall we tried to hit everything we could related to welding symbols. In the final episode we cover plug and slot welds, the remaining supplementary symbols to include the different contours of weld profiles that can be called out for different reasons.
We discuss the remaining weld symbols (Plug and Slot Welds) and how to prepare the materials for fit-up and how to weld them out. This includes depth of preparation, depth of weld, size and pitch (spacing). These types of connections are very common and used a lot in lap joints where a fillet wild will interfere with other pieces fitting into the area.
Surfacing are covered in great depth as they are very common in repair work to fill in worn areas of plates and shafts. Surfacing welds are perhaps the most common type of weld for students entering into the industry. They are welds placed side by side with 50% overlap to "build-up" a surface to its original height or thickness. They can also be used to correct poor fit-up in the shop and field.
This episode concludes the series and was really fun to do. We have had a lot of requests for welding symbols so we put this together and tried to include as much information as possible. Make sure to check this site for the downloadable welding symbol placement chart. Its free and can be printed off in any size you may need for the shop or your tool box.
We really appreciate the support and feedback from the audience. Make sure to tune in every week for new videos!