How To Read Blueprints For Welding?

Just like in any other industry, welders also rely on blueprints for welding to guide them in creating large welding tasks.

Although being able to decipher all the elements present in the welding blueprint is very helpful, it is not often required. As a novice, looking Into all the symbols and codes can be confusing and tricky, but you don’t have to worry at all. 

Let me help you figure out the basic meanings that some symbols represent. This article will give you a short guide on the most commonly used elements found in welding blueprints.

Overview: Step-by-Step Guide

A welding blueprint is created to present the precise expectations of a certain project. Typically, a blueprint creates an accurate view of the project from all possible angles. The symbols that appear in the drawing are codes for the type of weld, its size, and other processing and finishing information. 

Although the symbols in welding blueprints are not typically used in every industry, they are commonly required in the construction industry to ensure that expectations are met by doing quality work in a timely, cautious, and compliant manner. 

Parts of the Welding Blueprint

Since a blueprint has a composition of a myriad of letters and a variety of symbols, it is essential to know what each of them represents. But, before we learn the meaning behind every symbol that appears on the drawing, firstly, it is necessary to take a look at each part that comprises the blueprint.

Typically, a welding blueprint consists of six parts. However, not all of them may be present in some instances. For a better understanding, let me give you a brief explanation of each. 

  • Revision Block – A documentation of all the necessary changes made along the process. Usually composed of the date when the revision was made or a reference number for an area where a certain change had been imposed.
  • Drawing Number – A number assigned for each drawing that can be compared to a page number. 
  • Reference Numbers and Dash Numbers – Represent multiple parts of the drawing which might require undergoing certain processes. A specific set of numbers are used to ensure continuity and keep all the processes organized. 
  • Bill of Material – The most detailed portion of the blueprint containing sizes, quantities, and other essential information about the materials that will be needed.
  • The Scale – A portion that shows the actual size of the project to be made.
  • Title Block – Identifying the portion of the blueprint, which contains either the name of the project or a number representing it.

Letters, Symbols, and Other Elements: What Do They Mean?

After successfully learning how to identify specific portions of the blueprint, the trickier task follows. In this part, we will give you a summary of the letters, symbols, and other elements typically found in the welding blueprint.

Eleven single letters are mostly seen in a welding blueprint. Take a look at them and their distinct purposes below.

  • A – Angle of countersink
  • C – Chipping finish
  • F – Finish symbol
  • G – Grinding finish
  • L – Length of weld
  • M – Machining finish
  • N – Number of spot welds or projection welds
  • P – Pitch of Welds (center-to-center spacing)
  • R – Root opening; depth of filling
  • S – Depth of Preparation; the size of strength
  • T – Specification Process

According to the American Welding Society, a welding symbol consists of several elements. Typically, the skeleton of a welding symbol has a horizontal line called the reference line. Instructions are also present which consist of details on how to make a weld.

These instructions are connected by arrows to the horizontal line. Other elements in the forms of codes, drawings, and notes may also appear to convey specific welding information. The designation of welding, brazing and cutting processes are shown in the tail of the welding symbol. 

All elements are situated in specific locations. See the image below. 

Parts of the Welding Blueprint

Before we decipher how to read all the other elements in our welding blueprint, take note of the important concept that all welders should be familiar with, the joint types. Defined as an edge or point where two or more plastic or metal pieces are joined together, joint plays a vital role in all blueprints, and generally, with the process of welding. The most common types are seen in this image.

Letters, Symbols, and Other Element of welding blueprint

Moving forward, the following are the most common symbols seen along the reference line of the blueprint with their corresponding meaning. 

  • Fillet Welds – Usually appears as a triangular shape used to make corners, laps, and T-joints. This symbol represents a formation of two members, with weld metal being deposited in a corner thus, penetrating and fusing with the base metal to form the joint.
  • Groove Welds – Referred to as edge-to-edge joints for joining edges. Since they also come in various ways, they also join T joints, corner joints, and joints between flat and curved pieces. 
  • Plug and Slot Welds – Symbol that often requires drilling and filling of holes for overlapping materials.
  • Spot or Projection Welds – Typically connect overlapping pieces of metal at minor points with the use of pressure and electric current. 
  • Seam Welds – A similar process to spot welds that create a seam between two pieces of metal that are being fused.
  • Stud – A process wherein a metal stud is joined to a metal workpiece by heating both parts with an arc. 

More symbols are found in the photo provided. 

elements of blueprints

For other supplementary symbols, see this image.

various blueprinting symbols for welding

For a better and deeper understanding of all the visual representations shown in this article, check the American Welding Society Welding Symbol Chart. All photo credits belong to them.


Final Thoughts 

Although it is not often required to undergo special training and certification on reading and understanding welding blueprints, it is still essential as it assures precise and quality work. 

Simple and small-scale welding jobs may not expect the welder to have sufficient knowledge of reading the blueprint, however, it is always advantageous to at least understand the basic symbols.

If you are committed enough to make welding your career, choose the best programs available and master the art of reading welding blueprints in no time.

Check out the articles to find the best schools in Ohio, Georgia, New Jersey, and Florida.

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