The Transfer Line of Incoloy 800H is suffering from internal cracking as it isbeing in ourethylene cracking furnace. Could any body have comments? thank you

MGReis Transfer line - Incoloy 800 H -at the exit of ethylene furnace can develop internal cracking due to following possibilities: a. Bore carburization - predominantly result in IGSCC b. Excessive Creep related deformation damges : i.e., Internal fissuring followed by diametral expansion with resultant rupture if temperature of operation is > 850 deg cent. Depending on the size and thickness of transfer header - Incoloy 800 H design temperature can vary from 816-840 deg cent. This will also be predominantly IGSCC. Creep damages due to excessive temperature can also result in excssive carburization at the ID bore. Transfer headers are normally in closed loop system (at the exit of ethylene furnace). Hence Incoloy 800 H transfer headers are not normally subject to oxidation even during shut down. Polythionic acid corrosion (again SCC) may not be a possibility (unless flanged connections at some locations in the transfer headers) have been opened inadvertently during shut down time. If replacement is contemplated, evaluate the Incoloy 800 H header for thorough metallurgical examination to decide on the possible mechanizms of demages for the internal cracking TRust this helps you C.V.Srinivasan Nishi Engineers Pvt Ltd India E-mail: nishi@vsnl.com >The Transfer Line of Incoloy 800H is suffering from internal >cracking as it isbeing in ourethylene cracking furnace. >Could any body have comments? >thank you