How to Read Welding Blueprints?

How to Read Welding Blueprints?

Welding is not a simple field, and there are several matters to be aware of if you want to be a pro at it. One such thing is to be able to read welding blueprints for projects without any issue. It helps you in many ways, including saving welding costs, making the job faster, and giving you a quality weld result.

Unfortunately, even many veteran welders neglect to learn the ways to read a welding manual or blueprints. Most of them don’t even understand the welding blueprint symbols and thus, end up not getting the expected outcome on the first try.

Today, we will try to explain the method of reading such manuals in detail. We also added some diagrams as welding blueprint examples to make it easier to understand.

Welding Companies and Blueprints

Most welding companies today hire welders without enough knowledge of blueprints. The reason is simple- there are just not enough great welders that can read them. But they can still learn these symbols with ease.

They are not too complex to grasp. Companies should train their employees and actually make use of the blueprints in their field works. In that way, more people will be willing to know about welding blueprints.

As a welder, you can also hire any professional to train you.  Even the welding equipment manufactures know of these matters and can help you. Here, we will try to provide you as much help as we can.

Basic Welding Blueprint Structure

A normal welding blueprint can have many symbols to identify the actions required and some numbers to point out the size and other important things. There can be three types of welding blueprint based on the view- top view, side view, and front view. Below, you can see a basic top-view welding blueprint.

Basic Welding Blueprint Structure

First, we will talk about welding symbols.

Welding Symbols

Firstly, you will find an arrowhead on any welding symbol. It will point towards the area where the weld joint will be. The objective of a symbol is to explain the welding type and direction to the welder.

The arrowhead is attached to the leader line that connects to the reference line. The reference line will be horizontal, while the arrow can be upward or downward. There will also be a tail at the end of the reference line with one or many forks. The tail will explain the welding in detail.

Welding Symbols one
Welding Symbols two

Information about the weld type required on the metal will be on the reference line. They can be a geometric shape or a simple parallel line. It can be either on the bottom or top of the reference line. It is based on which side the welding will be on.

Welding Symbols three
Welding Symbols four

When following a weld blueprint, be careful not to confuse the weld symbols and the weld types. Pay attention to what side of the reference line the weld symbol is. If it’s at the bottom, the weld will be at the arrow side of the joint.

If it is at the top, the weld will be on the opposite side. If there are symbols on both sides, you got to apply the correct welding to both sides.

There are also different shapes for these welds, like V shape or Bevel shape.

Basic Welding Symbol

Try to memorize the common weld symbols first. Then go for the less famous ones. You can use this chart to help you out

Weld Symbol Locations

Welding Blueprint Letters

On a welding blueprint, there will also be many letters. These letters are there to make you aware of some necessary stuff regarding your project. They can mean the length or depth of the weld. Here are the letters to help you learn them.

  • The correct angle of the countersink
  • Chipping
  • F- Finishing
  • G- Grinding
  • L- Weld length
  • M- Machining
  • N- Number of spot welds needed on the place
  • P- Weld pitch in a center-to-center measurement.
  • R- Root opening and the filling depth
  • S- Strength; Preparation depth
  • T- Details of the specification

The letters are mostly there to point out any special weld or grinding method that needs to be done on the project. They are not that hard to remember once you work with them for some time.

Angle, Sizes, and Dimensions

Before welding, you should have a clear understanding of the dimensions of the weld to improve the welding quality. You will find many numbers on the symbol that indicates the angle of welds and their dimensions. It is possible to understand the length, width, or depth using these numbers.

For instance, you can find the length of the weld on the right of the weld symbol in inches. Meanwhile, the width/diameter can be found on the left in inches too. It is mostly written as a fraction. These numbers can also indicate the beveling of base metal.

You can also understand whether welding should be mirrored on both sides if the symbols are in the same position on both sides of a paper. If it’s not the case, then the welds offset each other. The following image shows some welding symbol numbers and meanings depending on their positions.

Welding Angel

Like before, if these numbers are under the reference line, they are for the arrow-side weld, while the top ones indicate the other-side welds.

Sometimes, it is necessary to conduct a series of small welds instead of a long one. They are mandatory for some metals with low heat resistance or thickness. They are shown with both the length of increment and the pitch of it.

Welding Size

A flag at the reference line intersection means that the welding must only happen on an open field and not in a workshop. Here is an example.

Welding Dimension

Specified Weld Symbols

There are many symbols that indicate a specified welding method. They also represent the finishing type. Let’s look at some basic weld symbols.

Fillet Weld

It is a triangle-shaped symbol. Fillet welds are used for corner joint, T, or 90-degree joints.

Fillet Weld

The perpendicular leg of the triangle is always on the left side.

Groove Weld

Groove weld is a method to connect two metal plates at their edges. There are various groove weld types, like square, bevel, or V.

Groove Weld

Plug or Slot Weld

They are to attach two metals one on another. In most cases, there will be holes through them to weld. The number on the left is the plug diameter or slot width. The numbers on the right indicate their pitch and length.

An Actual Welding Blueprint

We only added separate symbols and lines above to make you understand them. But an actual weld blueprint is kind of like this.

An Actual Welding Blueprint

Obviously, it will take a lot of time to actually master reading weld blueprints.

Frequently Asked Questions

Is It Hard to Read Welding Blueprints?

Honestly, welding blueprints will appear difficult the first time you try to use one. That is why you need knowledge of the details and take enough training to be able to read one perfectly.

How Do You Read a Metal Blueprint?

To read a metal blueprint, you must understand the details of the diagram properly. The piece marks are especially mandatory to learn, like A6 or 1C1. Also, focus on where the arrows point. Other than that, be careful of the angle, dimensions, and drawings.

Final Note

Unless you work with welding blueprints for some years, you may find them hard to interpret. If you want to be an actual master of welding, you should learn these blueprints. Keep in mind that even experts often find it hard to read a new blueprint. So, keep practicing.

Being an expert on weld blueprint will not only make you a better welding job candidate but also let you make high-quality welds with minimum effort and time. So, start learning them soon.

Last Updated on 2 years by Richard Boyer

  • June 8, 2022
Richard Boyer

Richard Boyer has been a professional welder for over 27 years of his life, and now he is a trainer and blogger providing critical information to anyone interested in welding. He is helping out both hobbyists, novice and professional welders to learn newer and better techniques. Read more about me

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