Casing and tubing core manufacturing technologies are as follows:


1. Chemical elements
Due to the harsh environmental services, the mechanical properties and corrosion resistance of coiled tubing are required to be very high. In order to optimize the chemical composition design of materials, clean control must be applied to the whole process of smelting and rolling to minimize inclusions and harmful elements such as S, P.


2. Processing
Due to the combination of hardening and Bauschinger effect caused by other factors after the dislocation multiplication, the strength of the tube body is controlled by the transformation method.


3. Heat treatment
The optimum control of microstructure and properties, especially high strength, high ductility and low residual stress, can be achieved by heat treatment of pipes.


4. Welding Technology
At present, HFW welding technology is mainly used in low carbon low alloy steel. It is necessary to study the optimum welding parameters (such as current, voltage, frequency, welding speed, forming angle, pressing quantity, etc.) and seam welding heat treatment technology.


5. docking
In order to realize continuous production of HFW tubes, long plates must be adopted first. At present, plate butting is mainly TIG, MAG and plasma welding.  The research method is friction stir welding.


6. Button control
Coiled tubing in service may cause local damage. The damaged or defective parts must be removed and welded to connect the tubing. The traditional butting method is manual butt TIG welding. The welding quality is difficult to control, which makes the current automatic welding technology.


7. New Manufacturing Technology
As a CVR technology, it uses continuous tubes of the same size and heates them to 940 C by on-line medium frequency induction heating through thermomechanical rolling. On the one hand, it realizes seamless or HFW seam optimization, on the other hand, it realizes variable wall thickness or adjustable. In addition, there are special continuous laser welding technology for stainless steel tubes.