Fabrication of boiler membrane screens of smooth tubes with welded distance pieces

Investigations of efficiency of boiler screens of smooth tubes, fabricated of 20, Kh2M and 12KhMF steels by automatic submerged arc welding were conducted. It was established that disordering of tube metal in heat affected zone of welded joint should be taken into account when fabricating such screens. Welding conditions must provide the minimal thermal effect on tube wall. Screen tempering after welding can be withdrawn if operation temperature doesn't exceed 530 deg. C