Connection method of casing pipe

With the rapid development of our country's economy and the continuous progress of industry,  steel casing pipe is widely used in various industries, promoting economic development. Oil casing manufacturers now have the ability to produce high-quality oil casing, providing more choices for various industries.

How should oil casings of different diameters be connected? Usually, casings of different specifications, models and materials have different connection methods.

For steel casing pipes whose length does not exceed 10m or whose diameter is less than 25mm, internal threads or external threads are generally used for connection. As for larger oil and casing pipes, since their internal structures are relatively complex, direct docking can also be chosen based on the actual situation. In addition, during the installation process, attention should also be paid to the sealing requirements at the interfaces at both ends of the oil casing to ensure the quality of the connection.

There are two main ways of connecting oil casing: threaded connection and welding. Threaded connections are convenient for disassembling a certain casing to find specific faults, but their pressure resistance is weak, so welding is often used in high-pressure wells and water injection wells.

(1)Threaded connection

Threaded connection sleeve is a widely used detachable fixed connection, which has the advantages of simple structure, reliable connection, and convenient assembly and disassembly. The traditional thread inspection method is to use thread gauges for contact or use a universal tool microscope for manual measurement. The workload is large, the work efficiency is low, and the measurement results are susceptible to human influence.

According to the shape of the plane graphics, threads can be divided into triangular, rectangular, trapezoidal and zigzag threads, etc. According to the winding direction of the spiral, it can be divided into left-hand thread and right-hand thread. It is stipulated that when the thread is upright, the spiral rising to the right is a right-handed thread, and rising to the left is a left-handed thread. Right-hand threads are generally used in machinery manufacturing, and left-hand threads are used only when there are special requirements. According to the number of spirals, it can be divided into single-thread threads and equidistantly arranged multi-thread threads. For the convenience of manufacturing, the thread generally does not exceed 4 lines.

(2)Welding

Welding is one of the main methods of casing connection. It is a process that connects two or more separate workpieces into a whole in a certain form and position. The essence of welding is to use heating or other methods to attract and penetrate each other between the solder and the welded casing, and rely on the cohesion between atoms to achieve a permanent and firm combination of the two metals.

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