Seamless Mild Steel Tube VS Welded Mild Steel Tube

Among the many pipes in the industrial field, seamless mild steel tube and welded mild steel tube occupy an important position. Although they both belong to the category of mild steel tubes, they have significant differences in manufacturing processes, structural characteristics, performance and application scenarios. difference.

Manufacturing process

1. Seamless mild steel tube

It is manufactured through processes such as perforation, hot rolling or cold drawing. In the hot-rolled seamless pipe process, the solid tube blank is first heated, then pierced by a piercing machine, and then rolled into the required size by a pipe rolling machine. Cold-drawn seamless pipes are drawn into finer pipes through a drawing die at room temperature. For example, for some seamless mild steel tubes with high precision requirements, the cold drawing process can better control the dimensional accuracy of the pipe, making the tolerance range of its outer diameter and inner diameter smaller.

2. Welding mild steel tube

It is formed by curling steel strips or steel plates and then welding the seams using a welding process. Common welding methods include ERW and SAW. High-frequency resistance welding uses resistance heat generated by high-frequency current at the welding edge of the pipe for welding. It is fast and efficient. Submerged arc welding welds by burning the arc under the granular flux layer. The weld quality is good and suitable for Thick wall pipe.

Structural features

1. Seamless mild steel tube

Its biggest feature is that there are no welds and the overall structure is uniform and continuous. This structure makes the stress distribution of the seamless pipe more uniform when it is under pressure, and there is no problem of stress concentration at the weld. Therefore, seamless mild steel tubes have more advantages in high-pressure environments and can withstand higher internal and external pressures. For example, in high-pressure hydraulic systems or boiler piping, seamless mild steel pipes are more reliable.

2. Welding mild steel tube

Since it is connected by welding, the structure of the weld may be different from that of the base material. Although welding processes are constantly improving, the weld is still a relatively weak link. When subjected to large pressure or impact, problems such as cracking may occur at the weld. However, the size and shape of welded mild steel tubes can be more flexible. With appropriate welding processes and quality control, pipes of various specifications and complex shapes can be produced.

Performance

1. Strength and pressure resistance

Seamless mild steel tubes generally have higher strength and pressure resistance under the same conditions. This is because its uniform structure is better able to resist internal pressure and external loads.

The strength and pressure resistance of welded mild steel tubes mainly depend on factors such as weld quality and pipe wall thickness. If the weld quality is good and the wall thickness is sufficient, it can also meet certain pressure requirements, but under extreme conditions of high pressure, it may not be as reliable as seamless pipes.

2. Corrosion resistance

There are no welds inside seamless mild steel tubes, which reduces potential corrosion risks caused by differences in metal structures at the welds. But this does not mean that seamless pipes are necessarily more corrosion-resistant than welded pipes. Their corrosion resistance is also related to factors such as the surface treatment of the pipe and the corrosive environment in which it is located. For example, in some environments containing corrosive media, whether it is seamless or welded mild steel tube, anti-corrosion coating treatment may be required to improve corrosion resistance.

3. Accuracy and surface quality

Seamless mild steel tubes can achieve higher dimensional accuracy and better surface quality through precision processing techniques, such as cold drawing. Its inner and outer surfaces are smooth, and it is suitable for occasions with high requirements on pipe accuracy and surface, such as shaft sleeves in machining or some precision hydraulic system pipes.

Welded mild steel plates may require additional processing to improve the surface quality after welding, and its dimensional accuracy is relatively difficult to control to the level of seamless pipes.

Application scenarios

1. Seamless mild steel tube

It is widely used in fields with high requirements on pipe quality and performance. For example, oil well pipes and high-pressure transmission pipelines in the oil and natural gas industry; high-pressure reactor connection pipes and high-precision chemical fluid transportation pipelines in the chemical industry; used in the field of machinery manufacturing to manufacture high-precision mechanical structural components, such as transmission shafts, etc.

2. Welding mild steel tube

It is often used in situations where the pressure requirements are not particularly high, but the cost is more sensitive or there are special requirements on the shape and size of the pipe. For example, ordinary water supply and drainage pipes in the construction industry, and some simple structural support pipes; in agricultural irrigation systems, welded mild steel tubes can be flexibly made into pipes of various shapes and lengths according to actual needs to meet irrigation requirements.

Summarize

In summary, seamless mild steel tubes and welded mild steel tubes have their own characteristics and play an irreplaceable role in different industrial fields and engineering scenarios. Understanding the difference between the two can help make scientific and reasonable choices based on specific needs in actual engineering applications, thereby ensuring the best balance of quality, efficiency and safety of the project.