Product standard:ASTM A269,A249,EN,TP304,321,316L.... Appliance:electric heater,heater ... ) Production Standard :ASTM A269;Enterprise Standard2) Material of commonly used stainless steel:TP304,TP321,TP316L,TP309S,TP310;Material of other stainless steel:202,302,INCOL800 ... the pipe/tube as well as the property of extensibility. welded stainless steel pipes for electric heater