Interpretation of Metal Fab Drawings (Moran)

Interpretation of metal fab drawings deals with symbols added to blueprints in order to apply the correct weld to a specific application. It is important to understand that the basis of these symbols is blueprint reading. It is suggested you understand blueprints before reading this book.

Interpreting metal fab drawings is a course that introduces the principles of interpretation and application of industrial fabrication drawings. Basic principles and techniques of metal fabrication are introduced by planning and construction of fixtures used in fabrication from drawings. Basic tools and equipment for layout fitting of welded fabrications are utilized. Covers the use and application of the AWS welding symbols. This course will utilize blueprints and welding symbols and will apply them in classroom and in shop as practical assignments.

The largest reason for understanding this information is to communicate between all parties involved. This could include the welder, engineer, quality control, as well as many more. This is a universal language that provides clear instructions for a quality part.

American Welding Society has created a detailed publication (Standard Symbols for Welding, Brazing, and Nondestructive Examination AWS A2.4) that gives an extended amount of knowledge in this language.

Below is an overview of what the elements of a welding symbol may or may not include. The welding symbol provides a visualization for the welder or those involved to be able to apply the applicable weld to the work piece.

Terminology of joints may play a large role in communication with supervisors and others working on the same weldment. Understanding the concepts associated with joint design as well as identification of parts is critical for any metal worker.

Joint Types

There are 5 basic joint types used in the metal fabrication field: Butt Joint: A joint type in which the butting ends of one or more work pieces are aligned in approximately the same plane. A butt joint has a possibility of many prepared faces. We will talk about these in subsequent chapters. Represented is a square groove butt joint.

Understanding Weld vs. Welding symbol

A weld symbol is not the same as a welding symbol. The weld symbol specifies the type of weld to be applied to a part. The welding symbol is made of several parts including the reference line, arrow, and weld symbol when required. The symbols in this book are a representation of what weld and welding symbols look like. There are specific design requirements when used in accordance to a blueprint.

Reference Line and Arrow

There are two parts that make up the main body of a welding symbol. These include the reference line and the arrow. The horizontal line that makes up the main body is called the reference line. This is the anchor to which all the other welding symbols are tied. The information that is pertinent for making the weld are place on the reference line in specific places. The arrow connects the reference line to the joint in which the weld(s) is (are) to be made. There are several combinations of the reference line and arrow, but the reference line will always be placed in a horizontal position. This symbol is also always read from the left to the right. If you have been around blueprints the arrow may look a lot like a leader line. They are not the same thing so be mindful when reviewing welding symbols.