How to Read Welding Symbols? Complete Beginners Guide
The easiest way to cut down the time and effort to figure out how a specific joint has been welded is to go through the welding symbols. All of these symbols must be properly given as well as depicted in other to do the job properly. You must know them like the back of your hand to become a professional welder.
In order to help you properly identify and learn about these signs, we’ve collected all the needed information on all the welding symbols out there and presented it here. If you’re interested in learning how to read welding symbols, feel free to continue along with us!
The Reference Line
The reference line is one of the basic symbols of any welding system. It plays the role of an anchor to all the other symbols as they’re all attached to it. This horizontal line comes with all the needed information required to produce the weld.
You’ll notice that the symbols are either drawn directly on the reference line or around it. An easy way to locate the reference line is to look near the joint as it’s always placed on or around it. You may find several reference-line signs in case it needs to specify the sequence of the operation.
The second essential symbol of a welding system is the arrow. You’ll find the arrow at the end of the reference line. The job of the arrow is to join the reference line with the joint that’s going to be welded.
Any required data about the arrow end of the reference line can be found underneath the line. The opposing side of the joint has been termed as the “other side.” Any info related to the other side is always kept above the reference line.
You need to know that it doesn’t matter at which end the arrow is placed – the information related will always be placed in their designated places.
In some cases, there might be more than one reference line attached to the one arrow. But here, the nearest reference line denotes the initial operation. On the other hand, any additional operations are denoted by the other reference line(s).
In most cases, you’ll see that the arrow points to two different sides of the joint. This is to indicate the two possible locations to place a weld. For example – if two steel plates were placed together to form a T, the weld can be positioned on either side of the shape at the stem.
In order to decrease the number of symbols, a lot of arrows can be used per welding diagram to illustrate the instructions.
The tail is the third most essential component of the welding symbol. This symbol is displayed as a less-than or greater-than symbol. It is also connected to the reference line but is placed on the facing across from the arrow.
The purpose of the tail is to provide information that has no fixed place anywhere else. This info is given on either left or right side of the tail as per requirement. For example – WPS or the approval from the American Welding Society can be added around the tail.
Given the WPS is likely to cover all the needed information for a particular joint, a welding system that is comprised of a reference line, arrow and tail should be sufficient to properly point the welding of the joint.
Now, even if the welding symbol WPS contains all the needed information, other added info for items such as grooves can be incorporated as well. The groove-weld sign is shown through a double line, half-circle, and a “V” or hash mark.
This symbol can be found underneath the reference line to signify a single weld on the side of the joint that has the arrow. It can also be situated on top of the reference line to indicate only a single weld can be placed on the other side of that joint.
However, the symbols can be found in both places if the joint requires double welding.
Complete Joint Penetration
As there are multiple different applications in which welds are needed to deliver complete joint penetration (CJP), you’ll find various methods that’ll indicate that.
For example – CJP can be added in the sign’s tail alongside the arrow and the reference line. This symbol is best suited when it’s unclear which equipment will be accessible in the workplace.
One more method of identifying CJP is by including either a single or double groove sign. The same symbol has to be applied on both sides of the reference line, but keep in mind that it won’t indicate the dimensions to specify the depth of the size of the weld.
Now that partial joint penetration (PJP) can be shown by adding the measurement of the depth of bevel as well as the weld’s needed size on the left side of the groove sign; or on both the sides in case of a double weld.
When working on constructing boilers or during pressure applications, fillet weld is the way to go. The sign looks like a right triangle, which can be found on the reference line. However, the triangle’s vertical line will always be situated on the left side.
The dimension that’ll reveal the size of the fillet weld is placed on the left side of the fillet sign and has to be on the same side as the reference line.
If you compare it to the groove-type welds, these don’t really course for the entirety of the joint’s length. The length is indicated by keeping the dimensions of the weld on the right side of the fillet sign. It’s important to have the right measurements in case the weld requires exact fitting.
Failing to do so indicates that the fillet weld goes through the full length of the joint. If you find fillet-weld signs on both the wings of the reference line, it means it’s an intermittent fillet weld.
Other Welding Symbols
Here are the overall symbols of a welding system. You will find any combination of the following eight signs in it:
- Basic weld symbols
- Reference line
- Dimensions and other data
- Supplementary symbols
- Process, or other references
- Finish symbols
Basic Weld Symbols
In this figure, you’ll find all the basic welding symbols along with their names.
Weld symbols are basically used to help you understand the welding processes when working with joining metals. Whether it’s a field or shop weld, local or global, these symbols will cover all as well as the contour of welds.
These symbols are used depending on the special needs of the joint system.
Arc & Gas Supplementary Symbols
Designation of Welding Processes by Letters
Designation of Cutting Processes by Letters
Other Common Weld Symbols
In the following diagrams, you’ll find the symbols for field weld and weld-all-around; resistance spot, and seam welds.
Weld All Around & Field Weld Symbols
Resistance Spot and Resistance Seam Welds
Location Significance of Arrow
In the case of fillet, groove, upset, flash, and flange welding signs, the arrow is attached to the welding sign reference line to one part of the joint which is termed as the arrow side of the joint.
Arrow Side Fillet Welding Symbol
The opposite side is named the other side of the joint.
Other Side Fillet Welding Symbols
Projection Welding; Resistance Seam & Spot; Plug Welding Symbols; Arc Seam & Spot
In the following symbols, the arrow is connected to the reference line and the outer surface of one of the members of the joint at the middle of the chosen weld.
The connected member is labeled as the arrow side member; the other is called the other side member.
Plug & Slot Welding Symbols
Near Side Welding Symbol
If the joint is represented with a single stripe on the drawing while the arrow is directed towards the line, the side of the arrow is labeled as the joint’s near side.
Arrow Side V-groove Welding Symbol
Other Side V-groove Welding Symbol
Welds on the Arrow Side of the Joint
Welds on the Other Side of the Joint
Spot Seam and Flash or Upset Weld Symbols
Construction of Symbols
Fillet, J-groove and bevel, flare bevel groove, and corner flange symbols are presented below with the vertical leg on the left.
In a J-groove or bevel weld symbol, you’ll notice the arrow pointed with a fixed break towards the member which is to be chamfered. If it’s obvious that the member is chamfered, the break from the arrow might be removed.
Info about the welding signs is positioned to read from left to right with the reference line in harmony with the normal conventions of drafting.
If a joint has more than one weld, the signs will be the following:
Complete penetration indication
If the basic weld signs aren’t enough to demonstrate the desired weld, it can be presented by a cross-section, detail, or any other data with a reference given in accordance.
Multiple reference lines to show all the operations
Other additional reference lines and test information
Weld-all-around welding symbols have to be located at the intersection of the reference and arrow line for each operation when applicable.
We hope we were able to properly introduce and help you out with any confusion regarding welding symbols. While it may seem like a lot to take in, you’ll soon learn how easy they are to understand once you go through the guide properly. If you have gone through our guide for telling what do the numbers of a welding rod mean then you will find it easy too. Best of luck with the new adventure!