API 5CT J55 and K55 are lower grade pipes commonly used in the oil and gas industry. They have the same chemical composition and yield strength range of 379-552 MPa, but different tensile strengths, 517 MPa for J55 and 655 MPa for K55. Compared with high-grade steel pipes such as N80, L80, and P110, J55 and K55 are lower in cost and suitable for non-corrosive oil wells and applications with lower strength requirements. J55 is a typical representative of oil casing, with high yield strength (55,000 psi) and good fatigue resistance. It can withstand high pressure and temperature underground and is widely used in various oil and gas wells to protect wellbore, prevent collapse and provide conduits for well fluids. J55 is usually produced in the form of seamless steel pipes, and welded versions are also available, which is economical and versatile. During drilling operations, casing is cemented to enhance the stability of the wellbore wall after it is lowered, and the tubing is nested in the casing to transport oil and gas to the ground. Due to its affordable price and reliable performance, J55 is one of the most popular materials in oil well pipe applications today. J55 oil well casing is an important tool used in oil drilling. It has excellent elongation performance. After the pipeline enters the well, it can be cemented. Unlike tubing and drill pipe, casing is not reusable.