How To Read Welding Blueprint - Learning The Basics

As there is no mandate for welders to learn about welding blueprints, often they’re negligent and skip on learning the basics of reading a welding blueprint. Furthermore, as welders often start from scratch without any sort of professional or vocational training, they unknowingly miss out on an important step in becoming a professional and efficient welder.

Today, we have a shortage of welders who are actually familiar with the dos and don’ts and the how and what of welding blueprints. It is very common for beginner welders to avoid learning about how to read a welding blueprint. 

Furthermore, many professional welders suggest that learning how to read a welding blueprint is not that necessary for beginners and hobbyists, which is unfortunate because many of these welders will, in fact, need to read a blueprint at some point in their career. 

As a result of this, beginners and many professionals who are unfamiliar with how to read welding blueprints make several mistakes and stay oblivious to the cause of all the mistakes.

Therefore, contrary to the common misconception, welders should have a basic understanding of how to read a welding blueprint as it not only increases overall welding efficiency but assists in increasing cost-efficiency. 

According to the recent data and local research, it is believed that more and more welders are investing their time and money in learning the basics of reading welding blueprints.

In this article, we will learn about the basics of welding blueprints, common symbols, the structure of welding symbols, must-know letters on welding symbols, and many more.

How is Learning the Basics of Reading a Welding Blueprint Beneficial?

Whether you’re a beginner or an experienced welder, you must have come across people in the field who may have mentioned the advantages of learning to read welding blueprints. 

And many of you, at different points in your career, may have considered learning to read welding blueprints. However, since you’re reading this article, you may not have moved on with the learning.

There can be a number of reasons why you stopped learning about welding blueprints ranging from difficulty to lack of guidance but the fact that you’re here is far more important. 

Going forward, it’s easy to feel overwhelmed or intimidated by the process but know that once you understand the core concepts, everything else will fall into place and make sense. In other words, once you begin with your learning, gradually with time and practice, you will be able to successfully interpret and decipher welding blueprint symbols.

Another reason to learn how to read welding blueprints is that there is currently a major demand for welders who are familiar with the concept of welding blueprints. A number of welding companies are looking for such welders in order to conduct classes or assist their team of welders in completing the project. 

Right now can be considered to be one of the most ideal situations for you to begin learning the basics of welding blueprints. There is a high probability that you’re missing out on a number of opportunities due to the lack of knowledge of welding blueprints so without any further ado, let’s begin this guide.

What is a Welding Blueprint?

Before starting on a welding project, welders generally outline a plan and design, and this architectural design is referred to as the welding blueprint. In simple terms, it can be compared to the design of a house that is to be constructed by the architecture or engineer. 

Similarly, welders create a plan that lays down the welding symbols illustrating the size, length, location, process, and other required specifications. Similar to any other profession, welding is a profession that requires both theoretical and practical knowledge. In order to achieve the best results, welders are required to apply theory to practice.

What are Welding Blueprints Symbols?

In the previous section, we briefly mentioned one of the most prominent features of a welding blueprint and that is the symbols in the welding blueprints. These symbols are simply an easy and time-efficient method used by welders to construct a well-crafted blueprint.

In simple terms, welding blueprint symbols are a set of alphabetical, graphical, and numerical denotations that are used to describe the position, size, type of weld, distance, and other important data required to accomplish the task. 

Having a proper understanding of these symbols allows welders to create their work as efficiently and effectively as possible. Furthermore, these symbols play a significant role in acting as a means of communication between the designer of the welding blueprint and the supervisors or welders working on the project.

In general, there are three types of welding blueprints, isometric, orthometric, and 3D. Furthermore, if you pick any regular set of welding blueprints, you will get accustomed to the three major views: the top, front, and right. 

At first, it may seem a bit complicated to understand just by reading it, however, once you take a look at an actual welding blueprint, you will be able to connect the missing dots.

Now, once you have picked a welding blueprint, you will be able to see a number of alien-looking symbols at different positions. These symbols are the heart of the blueprint, they indicate the type, number, and position of steps that must be taken in order to achieve the desired results.

If you’re a beginner or someone who is not familiar with the basics of welding blueprints, in general, you should know that welders often review and check the Welding Procedure Specification (WPS) before commencing the project. 

You see, WPS is a formal written document that lays down the welding procedures and provides the welder with the requisite information about the type of weld and electrodes that are to be used, the most ideal type of position for the weld, the thickness of the weld, the most favorable settings, and much more.

Once you’re done reviewing the WPS, you can now look at the welding blueprint and commence with the project.

Learn the Basics of Reading a Welding Blueprint

The three major steps that you need to keep in mind before starting the process is to look at a few sample welding blueprints, get familiar with the common welding blueprint symbols, and get accustomed to the three basic angles of view: the top, front, and right.
If you’re done looking at some welding blueprint samples. Now, let’s take a look at some of the welding blueprint symbols.

Understanding the Basics of the Welding Symbols

Welding blueprints consist of a number of symbols and each symbol has its own meaning. You can find the complete set of symbols in the American National Standards Institute (ANSI) and the American Welding Society (AWS). Before beginning with the welding symbols, let’s take a look at some of the basics of welding symbols:

  1. Each and every welding symbol consists of an arrow and a reference line (i.e., horizontal line). The reference line acts as an anchor to which all the other welding symbols are interconnected. On the other hand, an arrow connects the reference line to the joint that is to be welded.
  2. In general, the arrow line either points in the upward direction or the downward direction.
  3. Depending on the direction, you can decide the place for the weld. However, it is to be kept in mind that there are occasions when due to space constraints, the drawing does not allow the designer to fit the arrow on one side, and thus, the information should be interpreted by using the reference line. You see, the reference line will act as an indicator as to whether the weld goes on the arrow side or the opposite side.
  4. In addition to this, different types of welds are indicated by a different symbol. You can find a detailed list of symbols associated with the different types of welds on the American Welding Society website.
  5. Information regarding the type, size, position, length, and other relevant data is marked next to the welding symbol.
  6. One of the most crucial things is to remember the flag symbol. If you see a flag symbol in the welding blueprint then that indicates that the weld needs to be done outside on a field instead of inside a shop.
  7. If you come across a circle symbol then it simply implies that the weld has to go all the way around.
  8. You have to remember to go through the different symbols depicted in the AWS symbol chart in order to get familiar with them.

Type of Welds & Their Symbols

It is important to remember that each and every welding position has its own distinct welding symbol and it is generally laid near the center of the reference line either in the upwards direction or the downwards direction. 

This is important because the position of the symbol on the reference line denotes several important facts with respect to the position of the arrow line. In addition to this, if you see weld symbols on both sides of the reference line then you can make multiple welds on both sides of the joints.

Now, let’s look at some of the welding blueprint symbols and their meanings:

Fillet Welds

For starters, you have to remember that contrary to its spelling, the term “fillet” is pronounced as “fill-it”. This symbol is generally used to denote the 90-degree lap joints, corner joints, and T joints. After taking a look at the picture of the symbol, you can very well make out that this weld symbol generally is triangular in cross-section.

However, it is important to keep in mind that the shape is not always a 90-degree triangle and can often have several different variations. You just have to remember the degree of penetration of the welding metal as it determines the quality of the weld. Furthermore, the symbol is always on the left side of the triangle’s perpendicular leg.

Groove Welds

In general, groove welds are used in the making of edge-to-edge joints, however, it is also used in corner joints, T joints, and joints between curved and flat workpieces. One of the reasons for its popularity is the number of options available to weld. According to the AWS, a groove weld is defined as a weld that is done on the surface of the workpieces, between workpiece edges, or between workpiece edges and surfaces.

There are different types of groove joints, however, they either fall under the category of a single (used when there is only one side of the joint) or a double joint (used when there are both sides of the joint). Here are the different types of groove joints:

  1. V-groove
  2. J-groove
  3. U-groove
  4. Scarf
  5. Square Groove
  6. Flare V-groove
  7. Flare Bevel Groove

In most cases, groove welds consist of a reference line, tail, and an arrow line. Unlike the aforementioned weld symbol, groove weld symbols are much more complicated due to a variety of factors.

Plug and Slot Welds

Most commonly, plug and slot welds are associated with cases in which frames and metal sheets that are overlapping one another are joined together. In the general case scenario, weld metal is accumulated in the holes and penetrates. It further blends in with the base metal and the two workpieces form a joint. 

In the case of the plug welds, the diameter of each plug is mentioned on the left side of the weld symbol and the pitch of the plugs is mentioned on the right side. On the other hand, in slot welds, the width of each slot is mentioned on the left side of the weld symbol whereas, the length and pitch are indicated on the right side of the symbol.

Spot Welds

In spot welds, overlapping pieces of metal are connected at different small points through the use of pressure and electric current. The spot weld symbol is generally a circle and it can be placed in three different positions: above, below, and center of the reference line. [As seen in the image] It is important to note that if the weld symbol is positioned on the center of the reference line then it denotes that there is no side significance.

Seam Welds

Beginners often get confused between spot and seam weld symbols as there is only a slight difference. You see, unlike the spot welding symbol, the seam symbol is a bit more elongated on the sides as seen in the picture. Another major difference is the two parallel lines that go through the elongated circle.

Furthermore, you do not require any preparation as you do in the plug or slot welds, whereas you simply weld projects with the help of the top surface and melts it into the other workpiece by the use of heat.

Stud Welds

Lastly, we have the stud weld symbols. This symbol is also often confused with the above two symbols as well. As you can see in the picture, the symbol is round in shape and has a cross inside it.

This type of weld requires the symbol to be positioned on the arrow side of the joint. Furthermore, all the information with respect to the size, pitch, and amount of stud welds is indicated in the same location as spot and seam symbols. These symbols are most commonly used in shops.

What are the Meanings Behind the Letters on the Welding Blueprints?

When you were looking at sample welding blueprints, you must have come across a number of alphabetical symbols. Now, each and every alphabet indicates a different meaning. Let’s take a look at some of the alphabetical welding blueprint symbols:

  • A – Angle of Countersink
  • C – Clipping Finish
  • F – Finish Symbol
  • G – Grinding Finish
  • L – Length of the Weld
  • M – Machining Finish
  • N – Number of spot welds or projection welds
  • P – Pitch of Welds
  • R – Root Openings; Depth of Filing
  • S – Size of strength
  • T – Specification Process

What is the Implication of Dimensions and Angles?

One of the most crucial steps in learning about welding blueprints is the understanding of dimensions and angles. In the welding blueprint, the symbols also indicate the angle of the welds and root face dimensions. Most commonly numerical values play a significant role in determining the weld depth and angle specifications.

In simple terms, dimensions are referred to as the process of depicting the size of different objects. You see, dimensions are often mentioned below the reference line and it is used for the joint on the arrow side. Also, dimensions that are mentioned above the line apply to the joint in the opposite direction.

Final Words of Advice

My advice to all the beginners is to take steps slowly because if you try to learn everything in a short amount of time, you can end up being overwhelmed and as a result, all your efforts will go down the drain. Also, it can be a little complicated to understand everything, therefore, it would be better if you can practice your theoretical knowledge.

This article primarily focused on the basics of learning to read a welding blueprint, thus, in order to have a full grasp on the concept, it is highly suggested to routinely practice reading sample welding blueprints.