Why Weld Symbols Are Important in Manufacturing

In my years of experience working with manufacturing teams, I’ve seen both excellent and not-so-great practices around welding when it relates to manufactured products. In the not-so-great cases, the problems are ordinarily a lack of knowledge of how welds are defined. The issues may even consist of a failure to understand how the weld specifications are communicated internally from the engineer designing the product to the shop floor producing the product. In some situations, it’s even a lack of understanding of the importance of weld symbols.

The inquiries that I get around establishing internal weld processes and efficient weld symbol communication often consist of whether weld symbols are even required on drawings or how to decide what weld types should be used on a specific product. What size should a weld be? Will the weld hold up under real-world conditions?

Once we recognize that there must be specifications, internal processes, and efficient communication around welding, we gain an entirely new perspective. For instance, you may question who should determine a weld’s type and even size on a specific product. The answer to this question is twofold.

The first individual responsible for establishing weld processes is the engineer, who has designed the product for use, understanding how strong the weld needs to be based partially on the terminal environment that the weld will be in (more on how to test weld strength later). If the engineer hasn’t thought this through, the result could be a waste of material, over-engineering, or a weld failing in a worst-case scenario. The engineer can communicate this information to the shop floor in many ways: through weld symbols, notes, or by referencing internal weld specifications. The second individual responsible for weld specifications is the team members on the shop floor. The shop floor knows the equipment and machinery available, defining which weld-types are physically possible to create and which are not. In short, there MUST BE communication between the engineer and the shop floor to become efficient.

Even so, more inquiries may come to mind. Does the shop floor understand how to read the weld symbols? Do they have the equipment to meet the required weld specifications? What are the welding assets available? Who is performing the welding; certified welders, novice welders, or precision robotics? All four answers to these questions will affect how specific a drawing will display a weld callout.

When products are involved, it can be even more demanding. Does the weld prevent the leakage of dangerous gases, or does the weld hold two parts together, and leakage is not a concern? Regarding appearance, is it acceptable to have the weld bead shown as is, or does it have to be ground off, making it almost impossible to tell the part was welded together?

These are just some of the concerns that come to mind around welding. There are many other concerns such as material compatibility, customer requirements, X-ray regulations, inspection criteria; the list can go on and on. I will not cover all of these more specialized questions here.

This article will not answer every question you may have; yet, it will touch on some of the most popular questions. Through this, I intend to raise awareness, encourage you to examine your current welding methods, and prompt you to, perhaps, improve your engineering to shop floor welding process. Let’s jump right in and cover some of the most common questions:

Are Weld Symbols Required on My Drawings?

In short, the answer is a resounding “yes.” If welding is required for manufacturing, then the appropriate weld symbols are needed.

How Do You Decide Which Weld Type to Use?

You will likely have a few factors to consider when determining type-of-weld:

• The geometry of the parts being welded together
• The depth of penetration needed to weld the pieces effectively
• The function of the weld on the part as a whole

For example: Is the weld needed to prevent leaks or withstand pressure within a pressure vessel, or are the parts just attached with little to no stress and strain on the weld?

Here are some visual geometry examples:

If you look closely at the weld symbol, it reflects the shape of the geometry where the parts are welded together. This visual can help you determine what weld symbol is appropriate for the application.

Does the Shop Understand These Weld Symbols?

Unfortunately, this can vary from one organization to another. Some companies have standards in place that must be adhered to. These standards generally specify the type of approved welds for use on their products, period. Some have certified welders, and a variety of welding processes are supported like:

• • GTAW – Gas Tungsten Arc Welding
  • EBW – Electron Beam Welding
  • RSW – Resistance Spot Welding

Many high-performance companies use robotic welders to ensure consistent and repeatable welds for their products. I think that this is the best way to achieve a uniform weld. You see, the speed, length, and settings of the welding process can vary from one welder to another. If the welder, for some reason, welds slower than the next, there is a high chance of thermal expansion, which can ruin the product, and you then must scrap the whole part. Welding is more than a skill; I like to think of it as an art. Everyone is not great at it. Experience is a must, even for simple parts. Safety is another factor that must not be overlooked. Would you please ensure that you comply with the welding safety standards for your company, state, and OSHA standards before you start welding?