Manufacturing Processes And Procedures of OCTG Pipes

OCTG pipe is a special oil pipe, which refer to a type of steel pipes specially used for oil and natural gas extraction. Most of them are seamless pipes, but welded pipes also account for a considerable proportion. Different OCTG pipes often use different manufacturing processes, so what are the main types of processes? What is the main process?

The manufacturing process of OCTG pipes mainly includes the following:

1. Mandrel continuous rolling process

Applicable to pipes with an outer diameter of 21-178 mm, manufactured by mandrel continuous rolling and jacking process.

2. Mandrel tube mill rolling

Applicable to pipes with an outer diameter of 140-406 mm, rolled by mandrel tube mill.

3. Oblique rolling piercing and pilger rolling

Applicable to pipes with an outer diameter of 250-660 mm, manufactured by oblique rolling piercing and pilger rolling.

These processes usually do not allow the use of deformation heat treatment processes commonly used for plate and strip products for welded pipes, so high-strength seamless pipes must be produced by increasing the alloy content and combining appropriate heat treatment processes (such as quenching and tempering).

The procedures of OCTG pipes mainly includes the following steps:

1. Raw material preparation

First, select the appropriate raw material, usually steel. According to the size and purpose of the pipe, select the appropriate steel grade and specification.

2. Hot rolling

The raw material is heated to a high temperature and then hot rolled through a rolling mill to form a preliminary tube billet. This step mainly deforms the steel through the hot rolling process to achieve the desired shape and size.

3. Cold drawing

The hot-rolled tube billet is cold-drawn, and the diameter of the tube billet is gradually reduced through the die to improve its dimensional accuracy and surface quality. During the cold drawing process, the tube billet undergoes multiple stretching and compression to finally reach the desired size and shape.

4. Heat treatment

The cold-drawn tube is heat-treated, usually including steps such as quenching and tempering. Heat treatment can improve the mechanical properties and corrosion resistance of the pipe, ensuring that it has better strength and toughness during use.

‌5. Inspection‌

The heat-treated pipe is strictly inspected, including appearance inspection, dimension measurement, mechanical property test, etc. Ensure that the pipe meets the design requirements and standard specifications.

‌6. Coating treatment‌

As needed, the pipe is coated to improve its corrosion resistance and service life. Common coating materials include anti-corrosion coatings, lubricants, etc.

‌7. Packaging and delivery‌

Finally, the qualified pipes are packaged and shipped according to customer requirements. Packaging usually includes moisture-proof and shock-proof measures to ensure that the pipe is not damaged during transportation.

‌Differences in procedures of different types of OCTG pipes‌:

‌1. Drill pipe

Mainly used to drive the drill bit to rotate and circulate drilling fluid, and withstand high torque and axial tension. Its process includes hot rolling, cold drawing, heat treatment and other steps to ensure that it has high strength and corrosion resistance.

‌2. Casing‌ pipe

Used to support the well wall and withstand axial tension and internal pressure. Its process is similar to that of drill pipe, but additional anti-corrosion treatment may be required to adapt to the harsh environment of the well.

‌3. Oil pipe

Used to transport oil or natural gas, its process is similar to that of drill pipe and casing pipe, but it may pay more attention to the smoothness and corrosion resistance of the inner wall.

Summary

‌The differences in the manufacturing process of different types of OCTG pipes mostly depend on the selection and treatment of materials, and these process flows ensure that OCTG pipes have excellent performance and reliability in oil and gas extraction, meeting the needs of various complex working conditions.