Stainless steel pipe is an economic cross-section of steel, is an important product in the steel industry, can be widely used in life decoration and industry, many people in the market for making stair handrails, window guards, railings, furniture and so on. There are two common materials: 201 and 304. It accounts for about 8% to 16% of the total amount of steel, which is widely used in the national economy. Stainless steel according to the production mode is divided into seamless pipe and welded pipe two categories, so what is the difference between the two?

1. Differences in appearance

The most direct difference between stainless steel seamless pipe and stainless steel welded pipe is the appearance, the length of seamless pipe is basically inconsistent, and the length of stainless steel welded pipe is basically fixed. Stainless steel welded pipe surface is basically mirror, and stainless steel seamless pipe is off-white.

2. Differences in process

Stainless steel seamless pipe is a kind of hollow section, no joints around the strip of steel. The thicker the wall thickness of the product, the more economical and practical it is, the thinner the wall thickness, its processing costs will rise substantially; The process of this product determines its limited performance. It uses round tube billet as raw material to perforate, and it is made by cold rolling, cold drawing or hot extrusion production process. There are no welding points on the tube. Generally, seamless steel pipe has low accuracy: uneven wall thickness, low inner surface brightness, high cost of measuring, and there are pitting and black spots on the inner surface are not easy to remove; Its detection and shaping must be handled offline. Therefore, it embodies its superiority in high pressure, high strength and mechanical structure materials.

Welded steel pipe referred to as welded pipe, commonly used steel or steel strip after the unit and mold crimping formed welded steel pipe. The welded steel pipe has simple production process, high production efficiency, many varieties and specifications, and less investment in equipment, but its strength is generally lower than that of seamless steel pipe. Since the 1930s, with the rapid development of continuous rolling production of high quality strip steel and the progress of welding and inspection technology, the quality of weld is constantly improved, the varieties and specifications of welded steel pipe are increasing day by day, and in more and more fields, especially in the heat exchanger spare pipe, decorative pipe, medium and low pressure fluid pipe and other aspects of the replacement of seamless steel pipe.

3. Differences in performance and price

Seamless pipe in corrosion resistance and pressure resistance to high temperature and other properties are much higher than welded pipe. With the improvement of the welding process, the mechanical properties and mechanical properties are also slowly close to the seamless tube. Seamless tube in the production process is more complex, its price is more expensive than welded pipe.

Based on the characteristics and differences of stainless steel seamless pipe and welded pipe, the application should be reasonably selected to achieve economic, beautiful and reliable results:

(1) When used as decorative pipe, product pipe and prop pipe, it is generally required to have good surface effect, usually stainless steel welded pipe is selected;

(2) For generally low pressure fluid transportation, such as conveying water, oil, gas, air and heating hot water or steam and other low pressure systems, usually choose stainless steel welded pipe;

(3) For the pipeline used in industrial engineering and large equipment to transport fluids, as well as the boiler of power station, nuclear power station requirements of high temperature and high pressure, high strength fluid pipeline, stainless steel seamless pipe should be selected;

(4) Stainless steel welded pipe is generally used for liquid transportation below 0.8MPa, seamless pipe can be used to withstand liquid transportation above 0.8MPa. If the pressure requirement is not high, it is more economical to use welded pipe.