Difference between seamless pipe and seam pipe

From the technological point of view, the seamless steel pipes is formed by rolling once, heated with round steel, pierced, hot rolled, sizing, and straightened.

Seam steel pipes are also called welded steel pipes. They are welded by bending deformation of steel plates or steel strips. There are straight seam welded pipes and spiral welded pipes (spiral welded pipes are generally of large diameter).

Seam steel pipes and seamless steel pipes are classified according to the method of steel pipe production.

1. According to production methods, seamless steel pipes can be divided into: hot-rolled seamless pipes, cold drawn pipes, precision steel pipes, hot expanded pipes, cold spinning pipes, and extruded pipes. Seamless steel pipes are made of high-quality carbon steel or alloy steel, and are divided into hot-rolled and cold-rolled (drawn).
 

2. Welded steel pipes (Seam steel pipe) are divided into furnace welded pipes, electric resistance welded (resistance welded) pipes and automatic arc welded pipes due to their different welding processes. Due to their different welding methods, they are divided into two types: straight seam welded pipes and spiral welded pipes. The end shape is divided into round welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded steel pipes are welded by butt seams or spiral seams of steel plates rolled into a tube shape. In terms of manufacturing methods, they are divided into welded steel pipes for low-pressure fluid transportation, spiral seam electric welded steel pipes, direct coil welded steel pipes, and electric welded pipes. Seamless steel pipes can be used for liquid pressure pipes and gas pipes in various industries. Welded pipelines can be used for water pipelines, gas pipelines, heating pipelines, electrical pipelines, etc.

The difference between seamless steel pipe and seam steel pipe:

Different purposes: seamless steel pipe are mainly used as pipelines or structural parts for fluid transportation, mainly in the machinery industry, while seam steel pipes are mainly used in the construction industry, such as water, gas, compressed air and other low-pressure fluids. However, seamless steel pipes are used for all pressure pipelines. The price of seamless steel pipes is higher than that of seamed steel pipes.

Seamed pipes generally can withstand the maximum operating pressure of less than 20 kg, which is a safe range of use. It is generally used for low-pressure fluids such as water, gas, and compressed air.

Seamless steel pipe can withstand ultra-high pressure, of course, its wall thickness will increase accordingly, which needs to be designed according to pressure requirements. It is generally used for high-temperature and high-pressure equipment such as high-pressure oil pipes and boiler tubes. There are also seamless steel pipes for structural use, depending on the design requirements.

At present, there are also some seamless pipes with seam steel pipes, which are annealed to the weld seam, and the residual stress of the weld seam is made to make the weld seam equivalent to the base metal, and its pressure-bearing range is basically equivalent to that of seamless steel tube. Can also be considered for use.

Of course, there are also some seamless steel pipes on the market that use seamed steel pipes to be heated as a whole and then drawn or rolled with a core head. They are mainly small in size. This type of pipe is seamless steel pipe only in terms of appearance, and its quality is not very good. 

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