Nondestructive residual-stress measurement on the inside surface of stainless-steel pipe weldments

The instrumentation, technique, and procedures are described for the nondestructive measurement of residual stresses on the inside surface of pipe as small as 10 in. in diam. The instrument is based upon a unique position-sensitive scintillation X-ray detector which provides for the most compact X-ray stress-measurement instrument available since the introduction of film cameras four decades ago. This instrument is capable of applying the single-exposure technique of X-ray stress measurements which results in unprecedented rapidity of stress measurement consistent with excellent precision and accuracy. The results of testing the precision and accuracy of the instrument on a zero-stress powder and four-point-bend specimen are given. Residual stresses in four austenitic stainless-steel girth-welded pipes are presented illustrating the effects of the different welding procedures. The results from the pipes confirm the beneficial residual-stress condition of heat-sink-welding procedures.