The Manufacturing Process of Structural Steel Tubes for Mechanical Equipment

Structural steel tubes are fundamental components in the production of mechanical equipment, valued for their strength, durability, and versatility. These tubes are used in a variety of industries, from construction to aerospace, providing the structural support needed to withstand demanding conditions. The manufacturing process of these steel tubes is complex, involving multiple stages that ensure the tubes meet the necessary mechanical properties and quality standards. This article delves into the manufacturing process of structural steel tubes, explaining each critical stage, from material selection to final inspection.

 

 

Raw Material Selection of Structural Steel Tubes

 

The manufacturing of steel tubes for structural purposes begins with the careful selection of raw materials. The base material is typically steel, chosen for its superior mechanical properties, including high tensile strength, resistance to impact, and versatility. Depending on the intended application, steel grades may vary, with carbon steel, alloy steel, and stainless steel being the most common. The raw steel is usually supplied in the form of coils, billets, or slabs, which are then processed into tubes.

 

Steel Tube Forming of Structural Steel Tubes

 

Once the raw material is selected, the next step is the tube forming process. This involves shaping the steel into a tubular form through various methods. The two most common processes used are seamless tube manufacturing and welded tube manufacturing.

 

In seamless tube manufacturing, the steel billet is first heated and pierced to form a hollow tube. The billet is then elongated and reduced in diameter through extrusion or rotary piercing, creating a continuous tube without any seams or welds. This process results in a tube that is highly resistant to pressure and can be used in high-stress applications.

 

Welded tube manufacturing, on the other hand, involves the rolling of a flat steel strip into a tube shape, which is then welded along the seam. The welded tubes are typically produced using high-frequency electric resistance welding (ERW) or submerged arc welding (SAW). While welded tubes are generally used in lower-pressure applications compared to seamless tubes, they offer cost-effectiveness and versatility for a wide range of mechanical equipment.

 

Heat Treatment of Structural Steel Tubes

 

After the tube has been formed, heat treatment is often required to enhance the material properties of the steel. Heat treatment involves heating the hollow structural tube to high temperatures and then cooling them at a controlled rate to achieve specific mechanical characteristics such as hardness, strength, and toughness.

 

For example, annealing is a heat treatment process that softens the steel, improving its formability and reducing internal stresses. In contrast, quenching and tempering are used to increase the hardness and strength of the steel, making it suitable for high-performance applications. The heat treatment process also helps to relieve any residual stresses introduced during the forming process, ensuring the tubes retain their structural integrity during use.

 

Surface Treatment of Structural Steel Tubes

 

To enhance the performance and lifespan of steel tubes, a surface treatment is often applied. This step is crucial for preventing corrosion, improving wear resistance, and providing aesthetic qualities. The most common surface treatments for structural steel tubes include galvanizing, powder coating, and pickling and passivation.

 

Galvanizing involves coating the steel tube with a layer of zinc, which acts as a sacrificial barrier against corrosion. This is especially useful for applications where the tube will be exposed to harsh environmental conditions, such as in outdoor construction or marine environments.

 

Powder coating is another surface treatment option that provides both aesthetic and functional benefits. It involves applying a dry powder to the tube’s surface, which is then heated to form a hard, durable coating. Powder coating is widely used in equipment that requires both corrosion resistance and a visually appealing finish.

 

Pickling and passivation are processes that involve the removal of scale, rust, or other impurities from the tube’s surface, followed by the application of a passivating agent to prevent further corrosion. This process is particularly important for stainless steel tubes, where corrosion resistance is a key factor in maintaining the tube’s performance over time.

 

Tube Sizing and Cutting of Structural Steel Tubes

 

Once the surface treatment is complete, the steel tubes are subjected to sizing and cutting. In this stage, the tubes are measured to ensure they meet the required dimensions. This process involves adjusting the diameter, wall thickness, and length of the tube to precise specifications. Tube sizing is typically performed using cold drawing, which pulls the tube through a die to reduce its diameter and wall thickness.

 

In some cases, pilgering is used for additional reduction in tube diameter or wall thickness. Pilgering is a cold working process where the tube is passed through a pair of rollers, which compress the material, further refining its dimensions. This ensures that the tube meets the strict tolerances required for its intended application.

 

Cutting is the final step in this stage, where the long steel tubes are cut into specific lengths according to customer requirements. This can be done using sawing, laser cutting, or shearing, depending on the size and material of the tube.

 

Final Inspection and Packaging of Structural Steel Tubes

 

The final step in the manufacturing process involves a thorough inspection to ensure that each steel tube meets the required standards. After passing the quality control tests, the tubes are cleaned, inspected for any defects, and packaged for shipment. The packaging is designed to protect the tubes during transport and storage, ensuring they arrive at their destination in pristine condition.

 

Professional Precision Tube Products Manufacturer-CBIES

 

CBIES has been deeply involved in the field of precision tubes for many years, accumulated rich industry experience, and rooted in the Vietnamese market. It has won the trust of customers with high-quality automotive precision tubes and parts. Looking to the future, CBIES will continue to expand the Vietnamese market, refine products, and provide customers with better products and services. If you have any needs, please contact us.