Common methods of steel pipe manufacturing include seamless and welded techniques. This content will provide a comprehensive understanding of steel pipe production.
What Are Seamless Steel Pipes
Seamless steel pipes are manufactured using a hot rolling or cold drawing process, resulting in a pipe with no weld. This absence of welds ensures uniform and consistent pipe walls, making seamless steel pipes superior to welded steel pipes in terms of strength, pressure resistance, and reliability. They are widely used in industries such as oil, natural gas, chemical, electric power, boiler, and machinery manufacturing.
Some of the characteristics of seamless steel pipes are listed below
- High strength: The absence of welds contributes to overall strength, allowing these pipes to withstand high pressure and temperature.
- High reliability: The lack of weld defects reduces the risk of leakage and rupture.
- Uniformity: Seamless steel pipes have smooth internal and external surfaces, and uniform pipe wall thickness.
- Good corrosion resistance: These pipes are typically made of high-quality materials, providing good corrosion resistance.
- Wide range of applications: They can be utilized in various high-pressure, high-temperature, and high-corrosion environments.
Manufacturing Process of Seamless Steel Pipes
How are seamless steel pipes manufactured?
There are two main manufacturing processes for seamless steel pipes: hot rolling and cold drawing (cold rolling).
Detailed Description of the Hot Rolling Process Steps for Seamless Pipes
| 1. Material selection: | Choose suitable ingots or billets. |
| 2. Heating: | Heat the ingots or billets to around 1200°C. |
| 3. Piercing: | Use a piercer to pierce the heated billet into a hollow tube billet. Standard piercing methods include oblique rolling piercing and head piercing. |
| 4. Rolling: | Perform multiple moving passes on the tube mill to gradually reduce the tube billet’s outer diameter and wall thickness to form a required steel pipe. |
| 5. Sizing and reducing: | Using sizing and reducing mills, precisely adjust the steel pipe’s outer diameter and wall thickness to achieve the required size and tolerance. |
| 6. Cooling and cutting: | The steel pipe is cooled after rolling and then cut to the required length. |
| 7. Heat treatment: | Heat treatment is performed on the steel pipe to eliminate internal stress and improve mechanical properties (this is applicable to cold-drawn seamless steel pipes). |
| 8. Pickling and lubrication: | Remove the surface oxide scale and increase lubricity through pickling and lubrication of the cold-drawn tube billet (applicable to cold-drawn seamless steel pipes). |
| 9. Cold drawing or cold rolling: | Gradually reduce the tube’s outer diameter and wall thickness through multiple drawings or rolling on a cold drawing machine or a cold rolling machine to form a steel tube of the required size (applicable to cold-drawn seamless steel tubes). |
| 10. Inspection: | Conduct quality inspection of steel tubes, including appearance inspection, dimensional measurement, and non-destructive testing, to ensure they meet relevant standards and customer requirements. |
Detailed Description of the Cold drawing /Cold Rolling Process Steps for Seamless Pipes
| 1. Material selection: | Choose appropriate hot-rolled tube billets. |
| 2. Pickling and lubrication: | Pickle and lubricate the hot-rolled tube billets to remove surface oxide scale and improve lubricity. |
| 3. Cold drawing or cold rolling: | Utilize cold drawing or rolling machines to gradually reduce the outer diameter and wall thickness of the tube billet, forming a steel pipe of the required size. |
| 4. Heat treatment: | Subject the cold-drawn or cold-rolled steel pipe to heat treatment to eliminate internal stress and enhance mechanical properties. |
| 5. Inspection: | Thoroughly inspect the steel pipe for quality, including appearance, dimensions, and non-destructive testing, to ensure it meets relevant standards and customer requirements. |
What Are Welded Steel Pipes
Welded steel pipes are made by rolling a steel strip or plate into a tubular shape and welding the edges. There are two main types: straight seam welded steel pipes (ERW/HFW) and spiral welded steel pipes (SAW). They have low manufacturing costs and are used for conveying water, oil, and gas, as well as for construction and structural purposes.
Characteristics of welded steel pipes:
- Low cost: The production process of welded steel pipes is relatively simple, low cost, and suitable for large-scale production.
- Diverse sizes: Steel pipes of various specifications and sizes can be produced to meet different engineering needs.
- High flexibility: The production process is flexible, and different materials and methods can be selected according to other uses and requirements.
- Weld quality: Modern welding technology can ensure that the quality and strength of welds are close to the pipe itself.
Demonstration of Longitudinal Seam Welded Pipe (LSAW)
Manufacturing Process of Welded Steel Pipes
How are welded steel pipes manufactured?
The process for welding steel pipes is the same, except for the welding method used. Here is our explanation of the three welding methods.
Detailed Description of the Hot Rolling Process Steps for Seamless Pipes
| 1. Material selection: | Choose appropriate steel coils. |
| 2. Uncoiling and shearing: | Uncoil and cut the steel coils into strips of the required width. |
| 3. Forming: | Gradually roll the steel strips into round or other shaped tube blanks using a forming machine. |
| 4. Electric resistance welding (ERW) welding: | Weld the butt edges of the tube blanks using resistance welding to create steel pipes. ERW welding is typically done with high-frequency current. |
| 5. Submerged arc welding (SAW) welding: | Weld the butt edges of the tube blanks inside and outside with submerged arc welding to form steel pipes. SAW welding is usually carried out under shielding gas and flux to ensure the quality of the weld. |
| 6. High-frequency resistance welding (HFW) welding: | Use high-frequency current to quickly heat and melt the edge of the steel strip, and then squeeze the molten edges together using squeezing rollers to form a weld. |
| 7. Weld treatment: | Heat-treat and deburr the weld to ensure its quality. |
| 8. Sizing and reducing: | Precisely adjust the outer diameter and wall thickness of the steel pipe using sizing and reducing mills to meet the required size and tolerance. |
| 9. Inspection: | Quality inspection of steel pipes, including appearance, dimensional measurement, and non-destructive testing, to ensure they meet relevant standards and customer requirements. |
Summary
The above are the leading manufacturing processes of seamless and welded steel pipes. No matter which type of steel pipe, strict quality control and testing are the key to ensuring that the product meets standards and customer requirements. If you need steel pipes, please find the steel pipe products you want here.
