Connections of Oil Casing

Connections of oil casing
1. External upset direct connection method: pipe with an inner threaded section and thickened, and the other side external threading. Phase coupled together, the sleeve has a smooth inner surface,
2. Direct connection method: both ends of the tube is threaded inside and outside, is directly connected to the pipe smooth inside and outside surfaces.
3. Took over the connection method: threaded inner ends of the tubes are used to take over the connection. Outside the connection is smooth.
4. The coupling connection method: threaded outer ends of the tubes are connected with external hoop. Late into the internal connection smooth surface

In addition, recently, the method of welding the sleeve junction can make the tube surface smooth after welding.