Maintenance inspection of large fillet welded structures in pressure vessels

Historically, fillet welds have received less attention than have main seams in pressure vessel design and construction. Analysis of the causes of failure in vessels occurring after final acceptance inspection indicate that far more failures result from fillet welds than can be attributed to main seams. The paper describes an automated ultrasonic system designed specifically for inspecting large fillet welds. Details of its application to the fillet welds of stiffening rings in long, horizontally mounted, vessels are presented. Its potential for defect sizing and application to other forms of weld are discussed. (author)