R. N. Sharma and S. Singh Indian Oil Corporation Ltd. Refineries & Pipelines Division), Scope Complex, Core -2 7, Institutional Area, Lodhi Road, New Delhi - 110003
A leak in the Reactor R-1 of Coker unit was observed in the southern side of the dome to shell welding on 08.05.91. The reactor shell is made of 1Cr 0.5 Mo and is of 30/24 mm thickness. After detailed inspection, a through and through crack of about 530 mm. length along the edge of top fillet welding of pad (provided for attaching the lifting lug plate) was detected. Initially, to ascertain the leak, the reactor was pressurised with steam but no leak was observed. Then the reactor was subjected to hot vapour at its working temperature and pressure and leak was found. Incidentally this crack was also falling in the lower heat affected zone of top dome to shell circumferential welding and the gap between the two weldings was found to be approx 10 mm instead of generally recommended 150 mm. The crack was removed by means of grinding. With due precaution, welding and stress relieving were done. In dye penetrant test, radiography and during pressurisation with hot vapour, the repaired welding was found in satisfactory condition.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 2, pages 1049 - 1054 Publisher:Ashgate Publishing Company
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