Seamless steel pipe
A steel pipe made of a single piece of metal without seams on the surface is called a seamless steel pipe. According to the production method, seamless pipes are divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, and pipe jacking. According to the cross-sectional shape, the seamless steel pipe is divided into two types: round and special-shaped. The maximum diameter is 650mm and the minimum diameter is 0.3mm. Depending on the application, there are thick-walled and thin-walled tubes. Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemicals, boiler pipes, bearing pipes and high-precision structural steel pipes for automobiles, tractors and aviation.
Welded steel pipe
Welded pipe, also known as welded steel pipe, is basically a steel pipe made of steel plate or strip steel after crimping and welding. Welded steel pipe has a simple production process, high production efficiency, many varieties and specifications, and less equipment, but its general strength is lower than that of seamless steel pipes. Since the 1930s, with the rapid development of continuous rolling production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has been continuously improved, the varieties and specifications of welded steel pipes have been increasing, and more and more fields have replaced non-ferrous steel.
Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of the weld. The production process of the straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast; the strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe. Production of welded pipes with different diameters.
Compared with the same length of straight seam pipe, the length of the weld is increased by 30~100%, and the production speed is lower. Therefore, most of the welded pipes with smaller diameters use straight seam welding, and most of the welded pipes with large diameters use spiral welding.
What is the difference between seamless pipe and welded pipe?
1. Different process
Welded pipes are made by bending steel plates or strips through cold rolling and high frequency welding. Generally, there are spiral welding and straight welding. Seamless tubes are made by perforating billets or solid tube blanks, hot-rolled or cold-rolled. Seamless steel pipes are formed in one pass during rolling.
Ordinary welded steel pipes, such as water pipes, are generally welded by bending flat plates, and you can find a weld on it; the thicker diameter is generally a spiral weld. The seamless steel pipe is generally formed by pressing the molten steel in the molten state through the annular slit and then forming it by stretching and other processing processes, so that there is no weld.
2. Different appearances
The seamless steel pipe is rolled once and formed, the surface has no seams, and the performance is good. The inner wall of the welded pipe has welding ribs, and the surface generally has welding seams. Note: Now the welded pipe is seamless, and the traces can be seen by careful observation.
3. Different wall thickness
The precision of seamless steel pipe is low, and the wall thickness is relatively thick. The steel pipe of the welded pipe has high precision, and the wall thickness is usually relatively thin.
4. Different pressures
The welded pipe is generally about 10 MPa, and the pressure of the seamless pipe is higher.
5. Different raw materials
The seamless steel pipe uses steel billets or solid tube blanks. The seamless steel pipes are made of ordinary and high-quality carbon structural steel (Q215-A~Q275-A and 10~50 steel), low alloy steel (09MnV, 16Mn, etc.), Alloy steel, stainless acid-resistant steel, etc.; the welded pipe uses steel plate or strip steel.
6. Different performances
In terms of corrosion resistance, pressure bearing, high temperature resistance and other properties, seamless steel pipes are better than welded pipes.
7. Different prices
In the case of the same specification, seamless steel pipes are more expensive than welded pipes because the production process of seamless steel pipes is more complicated and its cost is higher.
8. Different functions
Seamless steel pipes are generally used as fluid pipelines that require special environments such as high pressure resistance and high temperature resistance. Welded pipes are usually used as low pressure fluid delivery pipes.
9. Different application scenarios
Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemical industries, boiler pipes, bearing pipes and high-precision structural steel pipes for automobiles, tractors and aviation.
Welded pipes are widely used in tap water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction.
Welded pipes are used for liquid transportation: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas; for structure: for piling pipe, for bridge; for wharf, road, building structure, etc.
Comparison Between Seamless Pipe and Welded Pipe
| Aspect | Seamless Pipe | Welded Pipe |
|---|---|---|
| Definition | Manufactured from a solid billet of metal without any joints or welds. | Made by rolling a flat sheet of metal and welding the edges together. |
| Manufacturing Process | Produced through extrusion or rotary piercing of a solid billet. | Fabricated by electric resistance welding (ERW), submerged arc welding (SAW), or spiral welding. |
| Surface | Uniform, smooth surface with no visible seams or joints. | Visible weld seam along the pipe's length or circumference. |
| Strength | Stronger due to the absence of weld seams; ideal for high-pressure applications. | Slightly weaker at the weld seam; suitable for moderate pressure applications. |
| Size Range | Limited to smaller diameters, typically up to 24 inches. | Available in a wider range of diameters, including very large sizes. |
| Thickness Consistency | Consistent wall thickness throughout the pipe. | Thickness may vary slightly near the welded seam. |
| Load Capacity | Suitable for heavy loads and extreme conditions. | Sufficient for lighter loads and less demanding applications. |
| Cost | More expensive due to the complex manufacturing process. | More affordable and cost-efficient for large-scale projects. |
| Applications | High-pressure pipelines (oil, gas), chemical plants, and power plants. | General-purpose pipelines (water, air, and gas), structural use, and low-pressure systems. |
| Corrosion Resistance | Better resistance due to the absence of welds. | Weld seam may be prone to corrosion if not properly treated. |
| Inspection and Testing | Extensive testing required to meet high standards. | Easier and less costly to inspect, especially at the weld seam. |
| Production Speed | Slower manufacturing process due to extrusion methods. | Faster production time, making it suitable for high-volume needs. |
| Weight | Heavier due to solid billet material and uniform thickness. | Lighter, especially in large diameters, due to the welding process. |
| Price Range | Higher upfront cost, often justified by durability and strength. | Lower cost, making it more economical for general applications. |
| Durability | Extremely durable in high-temperature and high-stress conditions. | Durable for standard and low-pressure environments. |
Conclusion
Understanding these differences allows for informed decision-making, ensuring the right type of pipe is selected based on project needs and specifications.What is the difference between seamless pipe and welded pipe, I will briefly introduce it to you today. I hope that after reading this article, I can provide you with reference and help. For more information, you can continue to pay attention to our website.
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