Tubing coupling is a kind of oil field drilling tool , which is mainly used for tubing connection . The coupling mainly solves the problem of fatigue fracture caused by stress concentration .
The tubing coupling structure is : the tubing end and the inner wall of the tubing are connected by taper thread , and the tubing end and the tubing are connected by the same thread and the same pitch . It has the characteristics of relieving stress concentration in the root of the outer thread of the pipe connecting with single taper thread . Effectively prevent the accident of oil well string breaking .
The coupling is divided into tubing collar and casing collar .
