API Round Thread
There are short round thread casing and the long round thread casing points. There are some advantages about round thread casing as follows:
1. Improve the abrasion caused by resistance when the thread tightening
2. Tighten the screw, the tooth tip provides a reasonable space for foreign particles and dirt
3. The circular arc tooth is not sensitive to local scratch or dent damage
Round thread due to its easy processing, good sealing performance and low price, is widely used in casing connection. In addition, it’s simple in site maintenance and use. In the test of different specifications of the round thread casing, use appropriate specifications of the thread gauge to test, when necessary carries on corresponding processing to the data.
Buttress Thread
In oil field tubing, buttress thread is a pipe thread form designed to provide a tight hydraulic seal. The thread form is similar to that of Acme thread the force is transmitted almost parallel to the axis and thread is about the same strength as standard v threads.
The advantages of buttress thread:
1) Buttress thread can withstand large tensile or compressive load, especially having sufficient tensile strength.
2) The design of the thread parameters are optimized to ensure that at least there is a tight fit around the thread, there is no gap, so that the sealing capacity of the terminal is greatly improved.
