How are seamless steel pipes made?

Seamless steel pipes (SMLS), as an indispensable and important material in modern industry, are widely used in many fields such as petroleum, chemical industry, machinery, and construction. Its production process is complex and delicate, involving multiple key steps and processes. Below, we will discuss in detail how seamless steel pipes are transformed from raw materials to finished products step by step.

1. Raw material preparation

The production of seamless steel pipes begins with high-quality billets or solid tube billets. These raw materials are usually made of high-quality carbon steel, alloy steel or stainless steel to ensure the strength and corrosion resistance of the final product. After entering the factory, the billets must undergo strict inspections, including chemical composition analysis, appearance quality inspection, etc., to ensure that the raw materials meet production requirements.

2. Heating and perforation

After the raw materials are ready, they first enter the heating furnace for heating treatment. The heating temperature is usually controlled between 1200℃ and 1300℃, the purpose of which is to soften the billet and facilitate subsequent perforation and rolling. The heated billet is fed into the perforator, and the center of the billet is perforated by the rotating head and rollers to form a hollow billet. The piercing process requires precise control of temperature, speed and pressure to ensure the uniformity of piercing and the consistency of the wall thickness of the tube billet.

3. Rolling and diameter reduction

The hollow tube billet after piercing enters the rolling stage. According to production requirements, hot rolling or cold rolling can be used for rolling. In the hot rolling process, the tube billet is rolled through a rolling mill at high temperature for multiple passes to gradually reduce the outer diameter and wall thickness to form a steel pipe with a certain size and shape. The cold rolling process is carried out at room temperature, and the tube billet is cold-processed by a cold rolling mill to achieve the purpose of reducing the size. The rolled steel pipe also needs to be further reduced to the final size by a diameter reducer to meet customer requirements.

4. Heat treatment and straightening

The rolled steel pipe needs to be heat treated to eliminate internal stress, improve the organizational structure and improve the mechanical properties. Heat treatment methods include annealing, normalizing, quenching, etc. The specific choice depends on the material and purpose of the steel pipe. After heat treatment, the steel pipe also needs to be straightened to eliminate the bends and twists generated during the rolling process and ensure the straightness and roundness of the steel pipe.

5. Finishing and inspection

The straightened steel pipe enters the finishing stage, including cutting the head and tail, grinding the surface, removing burrs and other processes to improve the appearance quality and dimensional accuracy of the steel pipe. Subsequently, the steel pipe needs to undergo a strict inspection procedure, including non-destructive testing (such as ultrasonic testing, eddy current testing, etc.), physical and chemical testing (such as tensile testing, impact testing, etc.) and dimensional inspection, etc., to ensure that the quality of the steel pipe meets the relevant standards and customer requirements.

6. Warehousing and delivery

The qualified steel pipes will be labeled, arranged in specifications, and then stored in the warehouse. Before delivery, the steel pipes must also be finally inspected and packaged to ensure that they are not damaged during transportation. Finally, seamless steel pipes are shipped to various fields of use, providing solid support and guarantee for various industrial equipment.

7. Introduction to special processes

In addition to the above-mentioned conventional production processes, the production of seamless steel pipes also involves some special processes, such as Pilgering process and cold drawing process. Pilgering process is a cold processing process that continuously reduces the wall thickness and outer diameter of the steel pipe through a series of bending rollers at 90° angles to each other. The cold drawing process uses a drawing machine to cold process the steel pipe, which can also achieve the purpose of reducing the size. The application of these special processes further enriches the production methods of seamless steel pipes and meets the special needs of seamless steel pipes in different fields.

Conclusion:
The production of seamless steel pipes is a complex and delicate process involving multiple key steps and processes. Through the careful operation and control of strict raw material preparation, heating piercing, rolling reduction, heat treatment straightening, finishing inspection and other processes, high-quality seamless steel pipe products are finally produced. These products play an important role in modern industry with their excellent performance and wide application fields.

Read more: Schedule 80 carbon steel pipe or American standard seamless steel pipe