Bigpond 1.Welding F 22 forged nozzle with P 22 - 10" Sch 160 pipe, joint preparation should match the lower thickness like what is normally done for a WN flange. 2.You can wrap up the F 22 nozzle during welding to avoid the temperature differential. FEA is not needed. 3.PWHT - both the F 22 and the P 22 joint and with thorough insulation of the joint and that of the F 22 forging, PWHT temp is usually 720 deg + or minus 10 deg cent. If you are not able to attain this temp due to heat dissipation or some other factor, you can keep at 690+/- 10 deg cent for a slighter longer time. This will reduce the stresses in weld and in the forging and piping. 4. NDT: Radiograph the weld joint or do UT Flaw check of the weld joint. Take hardness after PWHT on the joint /HAZ/parent forging /piping Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Sept 06. 2008 E-mal: nishi@vsnl.com >We have recently replaced a BFW preheater (U tube cnst.) >with F22 channel, all connected piping to it are F22 due to >presence of hydrogen gas at higher temperature. While >welding the connected piping (P22 10" Sch 160) , there are >concerns with the temp gradient of the nozzle which is 107mm >and was not heated completely. There are thoughts that due >to relatively cooler forging, the entire nozzle may be >stressed and may be favorable site for hydrogen attack. I >request your expert opinon on these queries: >1. How do these forgnings are welded where differential >thicknesses are involved. >2. How do we know that forging / nozzles are affected, if >yes that whether these are stressed and to what extent. >(will FEA will help) >3. Will doing the entire pwht of entire channel including >nozzle will help. >3. The pwht was done at 690 Deg C and distance of nozzle to >piping weld is 400 m from the shell. >4. Is there any NDT which can bring some confidence to what >we have done. >cheers >