The seamless steel casing pipes
are directly connected by threads, and the male end is connected to the female end. When connecting, the reliable performance of the sealing of the casing thread position is a key factor to ensure the normal production of the oil well.
The sealing structure of the new type of threaded oil casing is sealed by metal-to-metal contact, and there will be no gap problem, so it has a very reliable sealing performance; special threaded oil casing has been used in industrial equipment for a large area The use, especially in high-pressure oil and gas wells. However, these emerging threaded casings have very strict requirements for tightening torque. Under normal circumstances, there are three values: 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 threads is very small. In the actual oil casing operation, the tightening torque must be strictly Within this range, if the maximum torque value is exceeded, the sealing surface of the threaded oil casing will be destroyed. If it is less than the torque value, the metal sealing surface of the casing cannot have very good contact with the metal. The surface will not have the effect of sealing at all, so you must pay attention to this when using it.
Connection method of oil casing pipe:
1. External thickening connection method: one section of the pipe is thickened and has an inner threaded fastener, and the other end is an outer threaded fastener. When connected together, the sleeve has a smooth inner surface.
2. Direct connection method: Both ends of the pipe are threaded inside and outside, which are directly connected, and the inside and outside of the pipe are smooth.
3. Take over connection method: Both ends of the pipe are internal threaded buckles, and take over to connect. The outside is smooth after connection.
4. Coupling connection method: Both ends of the pipe are external threaded fasteners, which are connected by external hoops. After the connection, the inside becomes a smooth surface. In addition, recently, the method of welding the joints of petroleum casing pipes has been adopted to make the inner surface of the pipe smooth after welding.
Kg/m =[(Outer diameter-Wall thickness)*Wall thickness]*0.02466