Is there aproblem of developing cracking if old ASTM 106 Gr B pipes are welded to low alloy steel elbow A234 WP-22 and operate at 170 deg C in a preheater of kerosene recovery unit

Thankyou Mr. Srinivas. I was apprehensive because one welding expert from L&T suggested that such weld may give rise to cracking. Hope to interact in future. Maushumi

Maushumi Heater design of the same metallurgy is preferable - no doubt. Heater design with different metallurgy exist in some plants and work well if enough care is taken from beginning. Thermal expansion problem may be more with two dissimilar combinations than with same combinations ( i.e.,ferritic to ferritic combinations may not give thermal expansion problems seriously). With an existing old A 106 B pipe and weld necessity to use P 22 flange, with precaution in welding and post weld HT- as outlined in my first posting - may not give any problem for successful use. Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Oct 23, 2008 E-mail: nishi@vsnl.com >In general the heater designer will not mix the metallurgy >inside the process heater mainly due to difference in >thermal expansion for dissimilar material.May be in cold >service it may not give problem.I am afraid if such >dissimilar combination are there inside the furnace there is >a possibility of cracking during running condition due to >differential thermal expansion. It is better to use similar >metallurgy inside the process furnace to avoid craks/weld >failure. > >with regards,