Continuous seamless oil pipe is a new type of oil steel pipe with a single length of several thousand meters that can be bent repeatedly and achieve multiple plastic deformations. Continuous seamless tubing and its operating equipment are called "universal working machines". In the United States, Canada and other countries, continuous seamless tubing has become an indispensable petroleum equipment in oilfield operations. At present, the longest continuous seamless oil pipe is 9000m long. The core technology for the manufacture of this special seamless oil pipe is:
1. Chemical elements
Due to the harsh service environment, there are high requirements for the mechanical properties and corrosion resistance of continuous seamless tubing materials. In order to optimize the design of the chemical composition of the material, it is also necessary to realize the clean control of the whole process of smelting, rolling, etc., to minimize the content of inclusions and harmful elements such as S and P
.
2. Processing
After the work hardening caused by dislocation proliferation and other reasons and the Bauschinger effect work together, the transformation law of the strength of the seamless steel pipe body is controlled.
3. Heat treatment
Through the heat treatment of the seamless steel pipe body, the best control of the microstructure and properties is achieved, especially high strength, high plasticity and low residual stress.
4. Welding technology
For low-carbon micro-alloy steel, HFW welding technology is mainly used at present, and it is necessary to study the optimal welding process parameters (such as current, voltage, frequency, welding speed, forming angle, extrusion amount, etc.), research on weld seam and weld seam heat treatment technology.
5. Plate butt joint
In order to realize the continuous production of HFW welded pipes, the plates must first be lengthened. At present, TIG, MAG and plasma welding are mainly used for plate butt jointing. The method being studied is the friction stir welding method.
6. Seamless pipe butt joint
The continuous seamless oil pipe may cause local damage during use, and the damaged or defective parts must be cut off and the pipes connected by welding. The traditional butt joint method generally adopts manual TIG welding, and the welding quality is difficult to control. At present, the fully automatic welding technology is used.
7. New manufacturing technology
For example, CVR technology, that is, the continuous tube of the same specification tube blank is heated online to 940°C by medium frequency induction. Through thermomechanical rolling, on the one hand, the optimization or seamlessness of the HFW weld can be realized, and on the other hand, the variable wall thickness or diameter can be realized. In addition, there are special stainless steel continuous tube laser welding technology.
1. Chemical elements
Due to the harsh service environment, there are high requirements for the mechanical properties and corrosion resistance of continuous seamless tubing materials. In order to optimize the design of the chemical composition of the material, it is also necessary to realize the clean control of the whole process of smelting, rolling, etc., to minimize the content of inclusions and harmful elements such as S and P
.
2. Processing
After the work hardening caused by dislocation proliferation and other reasons and the Bauschinger effect work together, the transformation law of the strength of the seamless steel pipe body is controlled.
3. Heat treatment
Through the heat treatment of the seamless steel pipe body, the best control of the microstructure and properties is achieved, especially high strength, high plasticity and low residual stress.
4. Welding technology
For low-carbon micro-alloy steel, HFW welding technology is mainly used at present, and it is necessary to study the optimal welding process parameters (such as current, voltage, frequency, welding speed, forming angle, extrusion amount, etc.), research on weld seam and weld seam heat treatment technology.
5. Plate butt joint
In order to realize the continuous production of HFW welded pipes, the plates must first be lengthened. At present, TIG, MAG and plasma welding are mainly used for plate butt jointing. The method being studied is the friction stir welding method.
6. Seamless pipe butt joint
The continuous seamless oil pipe may cause local damage during use, and the damaged or defective parts must be cut off and the pipes connected by welding. The traditional butt joint method generally adopts manual TIG welding, and the welding quality is difficult to control. At present, the fully automatic welding technology is used.
7. New manufacturing technology
For example, CVR technology, that is, the continuous tube of the same specification tube blank is heated online to 940°C by medium frequency induction. Through thermomechanical rolling, on the one hand, the optimization or seamlessness of the HFW weld can be realized, and on the other hand, the variable wall thickness or diameter can be realized. In addition, there are special stainless steel continuous tube laser welding technology.
