Finding a welding symbol with no size indication is expected. When you are welding and come across a welding symbol without a size, don't panic. There are several reasons (both correct and incorrect) that someone may provide a welding symbol without a size indicator. It's happened to me plenty of times before, and I'm sure it will happen again.  

The American Welding Society (AWS) has standards for weld symbols, but many shops (like mine) have enabled their standards. At the basic level, You can't use a welding symbol with no size unless it is controlled on the drawing with detail or noted reference point. 

Detail or noted reference points can sometimes take a little digging to find, and there are often common reasons for a welding symbol having no size. Here is what to do and where to look to identify the size when it's missing. 

Welding Symbols Without Size in Blue Print Notes

The person putting together drawing notes can sometimes save themselves time by placing in the note section or in a callout that all welds are “X” inch. 

For example, you may see a note “For all typical fillet welds = ¼”” 

The drawing notes are typically easy to find in either the front or back section of the blueprint. 

Finding Welding Symbol Sizes from Shop Standards

AWS welding symbols are the standard in the USA. It is common for shops to create their own standards. Designing shop standards is mostly seen when the shop works on the same types of welds day in and day out to create their own “standards”—allowing the shop to save time. A unique standard does make it tricky if you are new on the job. It's not a bad idea to confirm with your crew members if the new shop you are working at has and “Standard Shop Practices.” 

Shop standards are most often simple changes. BUT that doesn't mean they can't get complicated. Creating custom symbols is done for a reason, so it's essential to pay attention to them. 

For example, a custom standard could be welding in a sheet metal shop with light metals. The size of the fillet weld is typically equal to the thickness of the material welded. 

It depends on your shop's communication practices for how to provide custom shop weld symbols. Companies will publish the standard welding symbols they've created for their in-house workers in some cases. You can find published symbol charts as a laminated sheet located in the shop or break rooms. It's an excellent idea to thoroughly review the areas you check-in or clock in as this is the most common area to display these notifications.  

Don't hesitate to ask, especially when shop workers have been there for some time. They may have the custom symbols memorized. 

If you are new, no one is going to judge you for asking. Your new team members will probably be more impressed you had the forethought to inquire about any standard shop welding symbols. 


Welding Symbol Without a Size on One Side

welding symbol missing sizeSuppose you have a welding symbol without a size on one side. One-sided dimensions is a common practice. It simply means to use the same size on both sides. Assuming the size you are referencing is on the arrow-side. The other side will be of the same size. 

Note: If you create the welding symbol, it is an easy way to save a bit of time when creating the drawings. It is much more comfortable and user friendly if you include size on both sides. 


Bevel Size with no weld size

If given a bevel size with no weld size, it is called a Complete Joint Penetration or JCP for short. When you don't receive the depth of the groove. (referenced as “D” in your symbol diagram) and groove weld size. (“referenced as “S” in your weld symbol) it indicates the weld requires a groove weld that extends through the thickness of the joint.

Auto Welds missing weld sizes

If you get a welding symbol from auto manufacture, you can almost be sure you'll be looking at a weld symbol with no size. Auto welding specs are often expecting you to use the original equipment manufactures welding specifications. 

Since most autos are using light gauge metals, it's often seen the material thickness also indicates the fillet welding size. The fillet size percentage is of the smallest of the pieces welded. For example, GMT autos fillet size is usually around 70-90% of the 

This trend isn't going away today it is even expected to see that many auto suppliers are referencing the manufactures weld specs in the print notes. 

Identifying welding size from previous weld

Trying to mimic previous welds or “eyeballing” a weld is not a recommended tactic, but it happens more than it probably should. Let's say you've exhausted all the above options. You've checked with your crew, confirmed the blueprints, checked for notes. Assuming what you working on isn't “high risk” or going to be an expensive mistake. One option is to look at a previously completed example and copy it. 

Reverse engineering a weld typically only works if you are in a shop set up more like an assembly line and working on the same welds day in and day out. If that's the case, someone else has likely completed the same weld you are working on.

If the individual who welded is around, ask them what size. Don't critique their work, remember your the newbie. But get as much information about the tips and tricks they've learned from creating the weld. They will likely be an excellent source for identifying the weld size. 

Don't give up!

If you are starting to feel like you are Nicholas Cage in National Treasure trying to decipher welding symbols, don't worry. Even the most advanced welders need to reference welding quick cards, books, or forums continually when you can't seem to find the correct welding size—that' when you get focused and start your research to find your next clue. The good news is, it's often a lot simpler than it seems. Use the tips above and if all else fails. Ask whoever created the blueprint drawing.