The behaviour of welds in service

Abstract

One of the primary reasons for attempting to understand the complex physical and metallurgical processes that take place during the welding — particularly the fusion welding — of metals is to increase the reliability of welded joints by specifying the optimum materials, welding procedures and quality-control techniques. For example, in the boiler of a major power station there may be thousands of pipe welds, and the failure of only one of these welds may result in a plant shut-down. In structural work, deficiencies in a single weld may not have such serious effects; nevertheless, if a weld in a critical location fails, the structure as a whole may collapse or be condemned. By studying the reliability of welds in service it is possible to obtain a measure of the success or otherwise of the welding engineer in achieving sound joints.