... heater,heater elements O.D.:from 6mm to 23mm 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. welded stainless steel pipes for electric heater