JOINTS EFFICIENCY (E) AND TYPES OF JOINTS

WHAT IS JOINT EFFICIENCY E?

a. It is a safety factor for welds.

b. It is a compensation for possible weld defects.

WHAT FACTORS AFFECT E?

It is type of joint, location of joint and amount of RT.

HOW DOES JOINT EFFICIENCY AFFECT t min?

As E decreases, required thickness increase.

HOW IS JOINT EFFICIENCY DETERMINED?

a. The code, section VIII – Table UW-12.

b. There are a few exceptions also listed in UW-12.

TYPES OF JOINTS

There are 6 types of joints:

1. Double welded.
2. Single welded with backing.
3. Single welded without backing.
4. Double fillet – welded.
5. Single fillet – welded with plug weld.
6. Single fillet – welded.

Based on the table below, please answer these exercises:

1. Shell made with Type 2 Joints and Spot RT was performed. What is E? 0.8
2. A shell is made with Type 1 Joints and Full RT was performed. What is E? 1.0
3. A shell is made with Type 3 Joints and Spot RT was Performed. What is E? N/A

WELD JOINT CATEGORIES

Category used here defines the location of a joint in a vessel not the type. UW-3

WELD JOINT CATEGORIES

Category A welds:

1. Longitudinal welds.
2. Shell to head weld for hemispherical heads.
3. Orange peel’ head welds.

Category B welds:

1. Circumferential welds.
2. Shell to head weld for non-hemispherical heads.

P/S See UW-3 for a complete listing of weld categories.

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