... /1629 seamless steel tubes, steel grade: St37, St44, St52, specifications: 1/ 4" -28", 13.7-711.2mm 8 Steel seamless steel pipe ( ... heat pipe) DIN17175-1979: carbon structural steel, steel grade St35.8-St45.8/ I ... 20, 35# # #, 45, #, specifications: 6-720* 1-70mm 10 Seamless steel pipes conveying fluid GB / T8163-1999, grades: 10,20, # #, specifications: ...