The External Upset End oil tubing adopts conical tube round thread. After the joint is upset, the connection and sealing are completed. It is one of the basic thread types issued by the Petroleum Association. The tooth shape is triangular and round bottom, the tooth shape angle is 60 °, the thread taper is 1:16, and the tooth shape angle bisector is perpendicular to the axis. After the thread is tightened, the interference fit seals on the sides of the internal and external threads. It is easy to process, has a tightness with the thread grease, and has some joint strength. On-site maintenance and application are relatively simple. 

The characteristics of the External Upset End oil tubing:

1. The connection strength is strengthened through the upsetting of the joint.

   Under the premise of not changing the thread shape, the size of the joint is increased through the upsetting process of the joint, which improves the strength of the joint and meets the deep request.

2. After the cooperation with the thread grease, there is a gap of 0.076mm between the tooth tip and the bottom of the thickened oil tubing. When tightening the thread, the gap between the crest is overflowing with thread grease. After the thread grease solidifies, the infarct leaks. Thus completing the sealing effect.

With the development of the petroleum industry, the geological conditions are becoming more and more severe, and the External Upset End oil tubing thread has stopped upgrading from time to time, gradually adapting to the request of special formations.