Welding is an important manufacturing technique that is being used worldwide. Due to advances in technology, science is growing very fast and the same is happening in this industry. Nowadays, engineers and welders from different parts of the world have to work together and have great performance. The solution to this problem is using the same form of communication. Welding symbols is that form of language that describes the process of building metallic structures. Hundreds of different welding symbols are being used for defining different conditions of welding or different types of welding. However, many of these symbols are acknowledged globally and if a symbol is not common, the designer explains its meaning in the plan. So, let’s see what those symbols mean.
- 1 What is the Big Picture on Welding Symbols
- 2 How Symbols That Include An Arrow Describe the Weld
- 3 What Are the Joint Types And How to Symbolize Them
- 3.1 Grooves on One Side of the Sheets
- 3.2 Grooves on Both Sides
- 4 How to Symbolize Additional Welding Properties
- 5 Special Process Symbols
- 6 Importance of Welding Symbols
- 7 Welding Symbols Certification
- 8 Conclusion
What is the Big Picture on Welding Symbols
Welding symbols seem to be very difficult when they are seen for the first time. However, if they are converted into their constituent symbols, they can be easily understood. There are two major types of welding symbols, the symbols that include an arrow, and those that don’t include it. Every type has stand-alone importance and it is responsible for a complete set of symbols. If you understand how these types work then you will be able to perform almost any task that you might come across in a plan.
How Symbols That Include An Arrow Describe the Weld
An arrow is often used in many plans to describe the properties of the weld. It is a universal symbol that most professionals understand. However, some variations will be discussed later. So, let’s get to it.
Basic Arrow Symbol
In the following figure, you can examine a common arrow symbol.
The symbol shown in figure 1 is the simplest symbol that is used for describing the surrounding conditions and characteristics of weld. This symbol consists of three parts as shown in figure 1. The right part of it indicates the required position of the weld. The arrowhead leads to the joint that has to be welded.
The middle part is known as the reference line. It contains detailed information about the characteristics of weld such as type of weld and specified location of weld. The bottom part of the line includes information about the side that the arrow is pointing while the upper part contains information about the opposite side of the lamina.
The left part of the symbol known as the tail contains all the complementary information regarding the weld. Complementary information is the information that cannot be categorized as specified information. Usually, complementary details include the weld’s standards, types of materials that are being joined, and the process of welding.
That’s the way of reading such a sign. Until now, I haven’t talked about how you write the information on it. So, it’s time to see how to write it.
How to Describe Fillet Welds
This type of weld joint is made when the two plates that are to be joined are at a right angle to each other. Under normal cases, the 90 degrees joint is known as fillet joint but some closer angles can also be considered as fillet joints. In the following figure, you will see an example of writing welding information about fillets.
All the symbols above describe the same weld. The number on the vertical side ( the left one) informs about the length of that side. The other one informs about the horizontal dimensions of the weld. In cases that both lengths are equal usually only the left one is written. However, please take a closer look at the plan before assuming this because sometimes there is some hidden information.
What If There is a Dashed Line
On an engineering or architectural design you might come across a different system. Apart from the one that we have already described and another one that is not frequently used. This alternative system can be recognized by the dash lines that are used below the reference line. Each system independently describes the weld but both systems cannot be used on the same drawing because it will become difficult to read.
It can be seen from figure 3 that the location of a welding symbol describes the orientation of welding. If the welding symbol is on the dashed line, it means that welding will be performed on the opposite side of the arrow line. Similarly, when the welding symbol will be on the reference line, it means that welding will be performed in the same direction as described by the arrow line. Some engineering drawings are very complex and they run low on space. This orientation is very important to understand because sometimes there is no place on the drawing to show weld in the same direction.
In the second way of explaining the welding symbol, the dashed line is not used below or above the reference line. It is opposite to the first system. In this system when the welding symbol is below the reference line, it means that the welding has to be performed in the same direction as the arrow line directs. Similarly, when the welding symbol is on the top of the reference line, the welding has to be performed in the opposite direction of the arrow line. The following figure informs you of all the ways that you can describe that fillet weld.
It is very important to differentiate those systems concerning the dashed lines. The use of any base system is not linked with any specific parameter and any system can be used in any kind of drawing.
What Are the Joint Types And How to Symbolize Them
On many occasions, some preparation of the seam is required before the welding process takes place. The symbols that engineers use are differentiated based on the way the joints weld up to each other. For instance, two different plates are placed parallel to each other and one plate is placed on the top of another and then they are welded from one side or the other side. Either it is to be welded from one side or two different sides, the welding symbol will help in defining it. Different types of joints and their symbols are described in detail in this section.
Grooves on One Side of the Sheets
Those joints that are only welded at one side are known as single-sided joints. There are 7 major types of single-sided joints. There are more symbols but the rest of them is a combination of these. All of these single-sided joints with their symbol and weld preps are given below.
The joint that has 45 degrees of weld prep on both sheets is known as a V groove. It’s called this way because if you put both pieces of metal next to each other, the cut area has the shape of V. In case that the angle is not 45 degrees then you have to write it in the drawing.
Weld with no Grooves
This is the simplest type of joints. This type of weld does not require any kind of weld prep. In this type of weld, plates that are to be joined have square ends as shown in its symbol (figure 6).
V Groove with Broad Root Face
This type of joint is similar to the V groove but there is a big difference. Both joints have a weld prep of 45 degrees (or any other angle) but the similarities end here. The difference between these two types is that the groove’s depth is smaller than the sheets’ thickness. In most cases, it does not go much farther than ¾ of the metal’s thickness. This type of weld forms a Y shape weld as it can be seen in Figure 7.
Flare Bevel Groove
A flare bevel groove is a unique way to prepare the welding area by making a 90-degree arc. On one of the sheets that need to be welded the edge is smoothened by this arc. The symbol of the single bevel joint is shown in Figure 8. The symbols take the shape of both pieces of metal.
This is an interesting type of preparation because it is the opposite of the flare bevel groove. The plate has one square end while the plate’s other end has a shape like a quarter circle. However, it has the opposite curvature of a flare bevel groove that allows the use of more welding material for the connection. In this way, a J shaped weld is made. It can also be seen in the symbol of the Single J joint given in figure 9.
In this type of joint, plates that are to be joined have a shape like a quarter sphere and the weld is carved up to ¾ of the metal’s thickness. When both ends are joined, a U shape weld is produced. The shape of the Single U joint can be more clearly seen in figure 10 along with its symbol.
Bevel Groove with Broad Root Face
This type of preparation process is similar to the V groove. The difference between these two welds is that in a V Groove with broad root face, the cut area does not reach more than ¾ of the metal’s thickness. In simple words, some space in the metal sheet below the weld is left. The weld has an r shape and it can be seen in figure 11 along with the symbol of this type.
Grooves on Both Sides
Until now, we have examined the preparation of only one side, However, some welds require grooves to be cut on both sides for optimal connection. There are three major types of preparation grooves on both sides. You can figure out the symbols for the rest of them if you understand the symbols below.
Bevel Groove on Each Side of a Single Plate
In this type, one of the two plates that has be joined does not have any prep. However, the other plate has on both sides a 45-degrees bevel groove. Those cuts end in the middle of the sheet. This way, the groove has the shape of the letter K. You can see the symbol in figure 12.
V-Groove On Both Sheets
It’s a common welding preparation on many occasions. In this case, there are two V grooves on each side that are meeting halfway along with the metal’s thickness. In this way, an X shape is developed along with the metal’s thickness. You can see a V-groove on both sheets symbol in figure 13.
U Groove On Both Sides
In this type of weld, both sides of the two plates have a shape of a quarter circle in the outward direction. In this way, they leave a portion of ¼ to ½ of the plate’s thickness from the center. It forms a U shaped weld on each side. You can see the symbol in Figure 14.
How to Symbolize Additional Welding Properties
Many times a weld must be performed in a certain way. Therefore, supplementary symbols are used along with ones that I have written above. Those symbols help in identifying the type of welding. The important parameters that are described through these symbols are the requirements of finishing features, location of weld, and weld’s characteristics. There are nine major types of supplementary symbols and they are described in detail.
This symbol indicates that weld requires to be finished in the outward direction. The shape of the convex finished weld is just like a balloon that is away from the weld.
Four columns will be used for describing the supplementary symbols. The first column will include the name, the second column will show the symbol, the third column will show the integration of the concerned supplementary symbol with the base platform, and the fourth column will show the weld’s shape. The details of the convex supplementary symbol are shown in figure 15.
The symbol of the concave is curved in the opposite direction of the convex symbol. As it is opposite to the convex symbol, it can be deduced that weld is required to be finished in the inward direction. Fillet welds are used to obtain such type of finish. Details are given in figure 16.
This symbol is used when there are requirements of machining the weld to take it at the same level as the plate. A straight line is used to indicate a flush finish that exhibits the required shape of plates after welding. Details are shown in figure 17.
When Initial Welding is Required
This type of symbol is used when there is a requirement of a small initial weld before the complete U-shape or V-shape weld. It has a curved line symbol and it is placed either on the top or below the line depending upon the required location of weld. Details are shown in figure 18.
Weld Around the Metal
This symbol is used to identify the section that needs to be welded from all corners. A circle is made at the point where weld entirely around is required. Figure 19 depicts the details. You can notice that the sheet of metal is welded from all sides even underneath the plate which is not visible in the figure.
There are many situations when the weld cannot be made inside the workshop. Due to certain reasons, it is required that weld is made on the working site.
Welding Between Two Points
This symbol is used when welding is required between two different sections. Two points A and B will be shown on drawing that will display the required area of welding. The symbol and other details are given in figure 21.
Insertion of Consumable Plug
During the welding operations, sometimes some free space is left between the two joining plates. To fulfill that space, a consumable plug is inserted. The consumable plug is fused inside the free space. Details are given in figure 22.
Staggered Intermittent Weld
When the weld is required to be staggered intermittent between the plate’s two different sides, this symbol is used. This symbol also indicates that weld along the full length is not required. A line passing through Z is used as a symbol to indicate such a situation. The symbol and other details are shown in figure 23.
In simple words, two similar welds are made on the two sides of the plate but they are flipped in opposite directions.
Special Process Symbols
Usually, in drawings, special processes are described through symbols that are explained in it. However, there some of them that welders must know them and you will not find an explanation of them in drawings. Here are the most common of them.
When one plate has a hole and it is welded on top of another plate, this connection can be performed with a plug. When the welding process is completed, the two plates are seemed to be fused into one another and weld is filled inside the hole. You can see in figure 24 that there two sheets of metal. The smaller one has a hole with a diameter of half an inch. The hole will be filled with welding material.
Resistance Spot Welding
When the resistance spot welding is used to fuse two plates with the help of heat produced from electrical resistance, the type of weld is known as a resistance spot weld. Its symbol is a simple circle just like a spot.
Resistance Seam Welding
Two parallel lines are passed through a circle that indicates the seam. The overall weld’s shape is just like the shape of a slot.
Importance of Welding Symbols
Welding is an interesting career and it has a worldwide scope. Welding is so much linked with engineering and engineering involves a lot of drawings. The same is the case with welding. When a welder is working at an international platform, he/she has to follow certain codes of conduct to meet the requirements of his profession. There are chances that welder is working in an area where he cannot understand the native language, then he/she has to perform welding by following drawings. These drawings contain certain welding symbols and it is very important for a professional welder who wants to pursue his career on an international level to learn and understand all these welding symbols. Therefore, learning welding symbols is very important for a welder who wants to seek his career on international platforms.
Welding Symbols Certification
A welder has to take many certification tests during his/her career. These certificates and tests are very important for a welder to grow on an international level. In all of these tests, there is a certification test for welding symbols. When a welder applies for an international project, working experience is not enough and certain qualifications are required. Reading this article will help you in recalling different welding symbols if you have already learned them or it will help you in identifying these welding symbols.
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