Modern types of welding open up many opportunities for welding masters, allowing both professionals and amateurs to realize their ideas. With the help of argon-arc welding, you can connect dissimilar metals, and with the help of a budget inverter, one can weld a fence near a country house.
Yet, sometimes, welding equipment and accessories are not enough for full-fledged work. When we talk about professional welding, employees should have a wide background and a knowledge base. It is important to learn how to make and understand welding blueprints. When reading welding blueprints, workers can find out all the comprehensive information about the metal to be welded, its thickness, characteristics, and places of future edge joints.
A blueprint is a full-fledged document issued for one specific part of a whole metal structure. It contains all the information a welder might need. Reading welding blueprints professionally is a must-have skill for any welder who wants to build a career in this domain.
How to read welding blueprints and what to use for this?
Each welding blueprint is characterized by depicting a future model from different angles. To begin with, any welding blueprint is depicted from three perspectives, namely:
- top;
- a front side;
- a rear side.
A welding blueprint is a schematic designation of a future product with the specification of the used materials and parts. Additionally, each draft has a certain set of signs that indicate the key information about the scope of work. These include such data as what type of welding is used for particular pieces according to their edges, in what direction a welding bead head, from what sides (one or both) joints are made, etc.
Parts of each Welding Blueprint
Each weld draft consists of several important sections that help clarify all the information about a future project. These are:
- The revision block. This is the place where all amendments, adjustments, and corrections to the project are documented. Before issuing a blueprint to the welder, each draft is corrected. For welders, it is necessary to study this block to avoid some common mistakes and better understand the scope of work.
- Drawing numbers. Drafts are usually enumerated. This is especially the case for large-scale projects that total dozens of pages of information. In such cases, each blueprint is enumerated to simplify reference to it in the text.
- Dash and reference numbers. These tools are applied to keep processes organized. Sometimes, one and the same process is used in several parts of the project. Using reference lines and numbers will help easily denote the process without long explanations.
- The scale. In this section, the exact size of all products and parts is specified. This helps welders to avoid calculating the size of a tangible product. They can realize the size when looking through this section.
- The bill of material. This part of the blueprint embraces all the details and written material about the number and size of required pieces and accessories for the work to be performed.
- The title block. This is the name of the project. If a welder deals with several projects at once, this will help distinguish between different types of blueprints and avoid confusion.
Once having studied all this information (usually provided as an introduction or reference), welders are ready to proceed to real weld drafts. To perfectly cope with the task, they need to know how particular symbols are deciphered. So, let’s get down to this issue.
A Standard Welding Symbol of each Blueprint
An arrow is the first thing that every welder faces on a blueprint. Arrows are indispensable welding symbols. It is a horizontal line that is found on every welding blueprint. An arrow points to the place and direction of a weld. Each arrow consists of several parts, namely a head, a leader line, and a tail (a reference line for additional info).
Its head is usually directed downwards or upwards to indicate the place of a weld joint. It is always depicted at a 45-degree angle.
The tail (next to the reference line) can have one or several forks for specifying additional information about the scope of work.
The leader line is a straight line that performs an important task since it conveys the key information about the purpose and way of the weld. Note that the position of welding symbols above or below the line is not accidental. Their placement plays a crucial role.
If you see a welding symbol depicted above the leader line, it means that a welder should make a bead on the opposite side of the joint that the arrow is directing at. At, vice versa, having a welding symbol below the leader line means that the welder should make a seam on the same side with a joint. If you see two welding symbols depicted above and below the line simultaneously, this indicates the necessity to make multiple welds from both sides of the surface.
All the supplementary information, details, or additional remarks are specified near the reference line (the tail).
Now, let’s see what kinds of welding symbols can be depicted near the leader or reference line.
How to read welding blueprints?
Kinds of Symbols
When a welder looks at a weld blueprint, various kinds of designations are found. Most blueprints use the following basic types of welding symbols:
- letters,
- shapes,
- lines,
- numbers.
Letters are widely used to indicate the length of the joint, the kind of finish, information about pitches or root opening, etc. Below, let’s consider the most common ones:
| L | weld bead length |
| A | countersink angle |
| M | a kind of machining finish |
| F | a finish symbol |
| C | chipping finish |
| G | grinding finish |
| P | the pitch of welds |
| T | specification process |
| S | the required weld depth of preparation |
| N | the number of required projection welds or spot welds |
| R | the weld depth of the filling and root opening |
Note that welders should not obligatorily know all these letters and keep them in their minds. Even experienced welders take a guide with them and look at such lists during the welding process.
The Way to Specify Angles and Dimensions
This information is required to understand the size of the project properly. A correct specification of dimensions and angles allows welders to clearly realize how long, wide, and deep a weld must be, as well as the size of the opening.
The diameter of a weld bead is specified on the left side of the main welding symbol and usually has a designation of a fraction of an inch.
As for the length of the weld bead, it is placed on the right side of the main welding symbol. The indicator is specified in inches as well.
As mentioned above, some blueprints required welding from both sides. In such cases, welding symbols are located both above and below the leader line. In this case, figures should mirror. Note that upper and lower symbols can have different figures, which means different widths and lengths of welds. Thus, pay attention to numbers.
A flag is another important sign that a welder should not skip. It is depicted in a place where a leader line and a reference line intersect, which means that this kind of weld should be performed in the field. In no case, do this project in your shop.
Types of Welds
Now let’s move on to the conditional signs that characterize them according to joints. Welded joints can be visible and invisible. If a weld bead is invisible, then it is shown as a dashed line, while visible ones are depicted as a solid line. An invisible joint is the one that is located on the reverse side of the part, and a visible bead is the one made on the front surface.
Each type of weld bead has a certain designation. According to the type of adjustment parts, they distinguish between butt, groove, lap, tee, and fillet slot welds. Some of them are designed for welding T joints or corner joints, while others are applied for curved pieces. Let’s take a closer look at basic welding symbols.
Butt Joint
A butt welded joint is made along adjacent ends, and the parts to be welded are to the same surface. This type of bead is the most durable, it is widely used in welding, especially, in critical metal structures. Before welding, it is necessary to carefully prepare the surface of the metal and make sure that all parts will be welded in accordance with the drawing.
Lap Joint
A lap joint is less demanding on the quality of work than the previous ones. But, at the same time, it does not have such good strength characteristics and tolerates loads worse. To make an overlap bead, place metal pieces parallel, but slightly offset to the side and partially overlapping each other.
Tee Joint
A tee welded joint is one of the most rigid and durable, but it does not tolerate bending loads well. To make a tee seam, place one part horizontally and the second vertically and weld with the first end to the surface.
Corner Joint
In a gusset, only the corners of your metal plates touch. The angle varies from joint to joint but is usually 90 degrees. This is the available large V space that needs to be filled. Corner joints occur in the drawings as an isosceles triangle or a right angle.
Groove Welds
A groove weld is formed along the ends of parts. The side surfaces of the parts are securely connected to each other due to edge-to-edge joints. The end seam is often used to weld metal of low thickness. Within this class, they distinguish different subtypes of groove welds. Here they are
- Square groove welds. This type of groove weld means that two parts must either tightly fit each other or have a slight space between edges. Square groove welds are marked on the scheme as two vertical parallel lines. Center-to-center spacing can be applied. If they have a certain kind of fraction, this option specifies the way of connecting them.
- U – groove welds. This type of weld deals with concave parts. To mark this type of weld on a blueprint, a quarter-oval is used, where open ends are directed away from the joint.
- V – groove welds. This kind of bead is made in the form of V. Thus, the letter V is used on welding blueprints to indicate this type of seam.
- J – groove welds. This type of weld is used to connect a square end with a concave part. A schematic designation reminds of the J letter since a vertical line with an adjacent quarter-circle line is attached to it from the right side.
- Bevel groove welds. This type of weld is used when two parts have different edges, i.e. the edge of one part is square, while the other one is chamfered. This kind of weld is marked as a right-angle triangle, where one side is missing.
- Flare bevel groove weld. This kind of seam weld is applied for curved and flat pieces. Welders use this technique when it is necessary to weld a round part to a piece with a flat surface. In this case, a vertical line is depicted perpendicularly above the reference line (not a leader one!). A quarter-circle is also depicted on the right side of the vertical line; its open end is directed on the opposite side of the vertical line.
- Flare-V groove welds. This kind of bead is applied when it is necessary to join two rounded parts. In this case, welders see two quarter-circles depicted next to each other.
- Plug and slot welds are designed to join overlapping parts. Plug and slot welds have a designation in the form of a rectangular.
Any welded joints, regardless of their type, can be single-sided (or as they are also called “SS”) or both-sided (abbreviation “BS”). One-sided seams are obtained by welding on one side of the joint, and two-sided groove welds are obtained by making a weld inside and outside.
Notes and References
Note that reading welding blueprints are not an easy task since lots of information is specified there. Moreover, no one guarantees you that all the data will be repeated at each stage. Thus, the welding procedure requires thorough studying and preparation. Many information is specified only once on the scheme, and welders should remember it for the whole project. Thus, the American welding society has accepted two common ways how to specify notes on drafts. All additional remarks are specified on the reference line. Here they are.
Welding Symbols without References
All the accompanying information that relates to a particular project is placed near the tail (on the reference line). Yet, there are cases, when one and the same technological process, notes, or features are applied to multiple kinds of welds. In such cases, guide writers note the following at the beginning of a weld blueprint:
- Unless otherwise specified, all actions are subject to standard specifications and tech processes.
- All the information about the piece is placed on the next page of the guide.
- Herein and after, all symbols regarding this type of weld are subject to strict abidance with standard specifications.
Thus, once noted, the rest of the welding blueprint will only have weld symbols without any remarks or notes on the reference line. That is why; blueprint reading requires thorough consideration and study by welder candidates.
General Notes
The second way of blueprint reading implies common information that does not need an introduction each time. These are the basics of the sphere that many welders perfectly know. These include:
- Make sure that the width of fillet welds is ¼ inches;
- Recheck whether the root opening is 3/16 inches for groove welded pieces.
Such rules are basic and obligatory for all professional welders. Thus, this knowledge comes as it is and does not require specifying it on the reference line.
Welding Blueprints Companies
Welding headquarters around the world face a lack of professional, skilled welders. Although many welders know how to weld and do it quite well, not all of them know for to read blueprints. This is the main drawback in the industry. While drafts are designed to simplify and speed up the tech process, welders spend more time getting acquainted with unfamiliar welding symbols.
Due to the gap in reading blueprints, companies set higher requirements for welder applicants and oblige their employees to master new skills and learn how to read blueprints. In this case, this is not the reason to fire such workers. It is enough to train and attend specialized courses. Reading blueprints is not very difficult. If you understand what weld symbol, in what place, and for what purposes is depicted, you’ll easily read blueprints.
Here, the question of where to find such training arises since not all companies have skilled welders who can explain how to read a welding blueprint correctly. Coaching classes are provided by the suppliers of welding equipment, industrial distributors and vendors, as well as manufacturers.
This skill is useful for all welders. Those workers who know how to read blueprints accurately have a competitive advantage over other welder candidates and cope with tasks quicker. Thus, the skill is useful for any employee who wants to develop a successful career in this industry and become a sought-after specialist.
The skill of reading blueprints is not very complicated. Once mastered, you’ll get this knowledge for your entire life. Moreover, the main thing is to realize the algorithm and that’s it. If you know what weld symbol is used to denote corner joints or plug welds, or how multiple welds are designated, reading blueprints won’t cause much trouble.
To conclude, note that the system of weld blueprint symbols is certified and accepted worldwide. Thus, all symbols are unified. Welders can use their own symbol for personal clarification, but for official documentation, only unified international designations must be applied. Therefore, if a welder knows how to read welding blueprints, he will succeed in any country and will be able to work perfectly, regardless of location.
Here’s a set of the most popular questions on the topic. Let’s answer them to conclude the article.
How do you read a fabrication blueprint?
To master the skill of blueprint reading, it is enough to understand what welding symbols can be used, for what purposes they are used, and what information each welding symbol conveys. Note that the place of weld symbol plays a significant role. Each line, quarter-circle, letter, and figure do matter. Yet, if you understand how it works, there won’t be problems with reading blueprints. If you want to learn welding symbols and master the skill of reading welding symbols, you can train courses provided by specialized companies.
How do you read welding details?
Note that all weld symbols are divided into basic ones and additional references. All the supplementary details are placed in the arrow tail. Basic designations are placed either above or below an arrow side, depending on the side of the joint to be welded. A geometric shape means a lot when workers read welding blueprints. To mark square or plane pieces, straight lines are used, while for curved or chamfered parts, arches are used. Watch this video and maybe you will understand this topic much more:
What do the letters mean in welding blueprints?
A number of letters are used for schematic designations of some processes. To read welding symbols correctly, one needs to know them. For example, G stands for grinding finish, L means weld bead length, A denotes a countersink angle, N means the number of required projection welds, M serves to specify a kind of machining finish, P defines the pitch of welds, F means a finish symbol, C is used to show chipping finish, etc. Note that welders should not obligatorily know all these letter designations by heart. Many welders, even experienced welders, take letter sheets with them and look into such reference books to understand how to read welding blueprints and read welding symbols.
How do you show welding in drawing?
Depending on the type of welded pieces, lines or quarter-circles can be used. If one has to designate a part with a square edge, then lines are used. For depicting chamfered or curved pieces, quarter-circles are applied. Note that the direction of lines and arches also matter and indicate the way surfacing welds are made.
How to read welding blueprints and Shop Drawings with Weld Symbols?
Studying welding blueprints starts with finding an arrow and defining the place of the joint to be made. The arrow will be directed to the place where a fillet or groove weld is needed. Next, find out whether a one-side or two-side bead is required, depending on what arrow side a weld symbol is located on. The third step implies defining the type of weld. Find a weld symbol (lines, letters, and other shapes) that defines a kind of fillet or groove weld to be made. Study other important information specified near the reference line.
How to read welding blueprints metal fabrication?
To read weld symbols, workers should know what designation stands for what process/item/piece. Thus, horizontal lines usually denote surfaces with square edges, while quarter-circles are used to denote pieces with chamfered or rounded edges. Also, note that the place of the weld symbol along arrow points and a reference line does matter. Mainly, placing a weld symbol below or above a pointing arrow means the side from which a welder has to make a bead.
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