api 5ct l80 13cr casing and tubing According to the manufacturing process, oil pipes can be divided into seamless pipes and electric welded pipes. Seamless pipe is a kind of forged steel pipe without welding seam, which is made of hot working steel. After pressing, stretching, heat treatment and other processes, it reaches the standard size of oil pipe, forming a seamless oil pipe series. Electric welding pipe is a kind of pipe with a longitudinal weld formed by resistance welding or electric induction welding without filler metal. The welding edges are squeezed together by mechanical pressure, and the standard size oil pipes are reached through heat treatment and other processes, forming a series of electric welding pipes. Tubing is pipe used for the transportation of crude oil and natural gas from an oil or gas layer to the surface after drilling is complete. It is made to withstand the pressure generated from the extraction process.…