The PQR shall include the composition and flow rate of the shielding and inert gasbacking, when used.
焊接工艺评定记录单上应包括封底焊时所用的惰性保护气体组成成分和流率。
2
They cause all the welding of double tubes, joint boxes and gas-collecting tubes to realize the backing weld of TAW-P. The quality of the double tube waste heat boilers have been improved.