... ) Material of commonly used stainless steel:TP304,TP321,TP316L,TP309S,TP310;Material of other stainless steel:202,302,INCOL800,840,8253 ... delivery: bright/annealing Note:Producing stainless steel welded pipes used for electric heating tubes for well over a dozen years, ... and exterior surface of the pipe/tube as well as the property of extensibility. welded stainless steel pipes for electric heater