... element,heater O.D.:from 6mm to 23 Features: 1) Production Standard :ASTM A269;Enterprise Standard2) Material of commonly used stainless steel:TP304 ... ,TP321,TP316L,TP309S,TP310;Material of other stainless steel:202,302,INCOL800,840,8253) ... /tube as well as the property of extensibility. sell stainless steel pipes for heater tublar