The oil casings are directly connected by threads, and the pin is connected to the box. The robustness of the sealing of the casing thread position during the connection is a key factor in ensuring that the oil well may be deformed. The sealing structure of the new type of threaded oil casing of the end thread of the oil casing pipe is a metal-to-metal contact seal, there will be no gap problems, so it has a very strong sealing performance; special threaded oil casing has been abroad Has been widely used in industrial equipment, especially in high-pressure oil and gas wells. However, these new types of threaded bushings have very strict requirements for tightening torque. In some cases, there are three values of maximum torque, optimal torque and minimum torque. The three values of different threaded oil casings are also different. The range between the maximum torque and the minimum torque of some special threaded officials is very small. In the actual oil casing operation, the tightening torque must be strict The operation is within this range. If the maximum torque value is exceeded, the sealing surface of the threaded oil casing will be destroyed. If the torque value is less than the value, the metal sealing surface of the casing and the metal cannot be very good. If you touch the name, the foundation will not achieve the results of the seal, so you must pay attention to this when using it. In order to improve the sealing performance of the threaded connection position of the oil casing and the life surface of the oil well.