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This paper discusses the apparatus necessary, and the procedure used in the gamma-ray radiography of both circumferential and longitudinal seams in welded piping. Also discussed is the effect of size of radiant source, distance from source to film, metal thickness, and type of film on the resultant radiographic sensitivity.
An accurately drilled test block, having three series of holes of
Two circumferential test pipe welds were made in which many defects, common to welded piping, were purposely made. These welds were first radiographed and then sectioned in many places, polished and etched and used to check the actual defect with the radiograph.
Two types of penetrameters were placed on both the source side and film side of the pipe welds. It is the author's opinion that there is little if any practical difference in the results obtained with the penetrameters in the two positions (at least for wall thickness up to 1.5 in.). It is agreed, however, that penetrameter detail is slightly better when the pentrameters are placed on the film side, which of course does not give an absolutely true picture of the detail of a defect comparable to the size of the penetrameter holes which is close to the root of the weld.
Also discussed and illustrated are a few of the various types of piping radiography encountered in the piping industry.
Emerson, R. W.
Metallurgist, Pittsburgh Piping and Equipment Co., Pittsburgh, Pa