Introduction

There is a lot of material common to the electrically-based welding processes SMAW, GMAW, FCAW, and GTAW, so it makes sense to cover them all at once. The joints and positions are also common to OAW. These items are:

• Joint types

• Joint edge preparation

• Parts of a weld

• Selection of joint preparation

• Welding positions

• Other types of welds

• Welding terminology

• Welding cables

• Safety equipment

• Safety practices

Joint Types

What are the five basic joint types?

• Lap joint

• Butt joint

• Corner joint

• T-joint

• Edge joint

See Figure 4-1.

Figure 4.1: Joint types

Joint Edge Preparation

Why is edge preparation done?

Joint preparation provides access to the joint interior. Without it the entire internal portion of the joint would not be fused or melted together making the joint weak. Remember that a properly made, full-penetration joint can carry as much load as the base metal itself, but full penetration will only occur with the correct joint preparation.

How are edge shapes for weld joint preparation made?

Usually, they are made by flame cutting, plasma arc cutting, machining or grinding however, castings, forgings, shearing, stamping and filing are also common methods used to prepare material for welding.

What edge shapes used in preparation for welding?

See Figure 4-2.

Figure 4.2: Edge shapes for weld preparation

Edge Preparation Terminology

What are the principal parts of V-and U-groove joint preparations?

• Depth of bevel

• Size of root face

• Root opening

• Groove angle