... A,B,X42,X46,X52,X56,X60,X65,X70,X High Quality Carbon Steel Drill Pipe We can produced drilling pipe(API5D,APISEPC7, ... walking beam quenching furnace,, hot and cold straighten device, friction welding machine, middle frequency heat treatment, numerical control lathe and compete ... analysis of each heat of steel.Strict full-length inspection especially on the weld-neck region ensures the drill pipes ...