FAILURE ANALYSIS OF CRACKED REDUCER FLANGE

摘要

A cracked flange was submitted to Kuwait institute for scientific research by a local petroleum company for determination of the cause of the failure. The cracked flange was a reducer flange.a 10 cm(4") × 3.75 cm (1.5"), of a reactor outlet (V41-002) drain line operating in refinary plans of the company since 1984, see figure 1 for the location of the flange with respest to the (V41-002) reactor in the refinary of the company. The flange made of an austenitic stainless steel ,UNSS No. 321. The operational pressure and temperature of the drain line of the reactor outlet were 1907Psig(13.2MPa) and 763° F(406C°),respectively. On the other hand, the design pressure and temperature of the drain line of the reactor outlet were 2240 Psig(15.5MPa) and 800°F(426.6C°),respectively. The reactor feeds the drain line with hydrocarbons of H2, H2S, H2O,and NH3. Also it has been reported that the partial pressure of the hydrogen was 1600Psig(11.0Mpa) in service as compared to the design partial pressure of 1750 Psig(12.2MPa). In addition, leaks of hydrocarbons were observed by the operational engineer of the company which resulted to shutdown of the reactor.