... Product standard:ASTM A269,A249, JIS,EN,TP304,321,316L.... Appliance:high quality electric element,heater O.D.:from 6mm to 23 ... annealing Note:Producing stainless steel welded pipes used for electric heating tubes for well over a dozen years, the company has ... experience and technical strength. In response to customers' requirements for the electric heating tube manufacturing process, we havr worked out ...