The difference between seamless pipe and welded pipe in process

The difference between seamless pipe and welded pipe in process

From the technical point of view, the seamless steel pipe is made by one-time rolling, round steel heating, perforation, hot rolling, sizing and straightening.

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

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

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

2. Welded steel pipes (seam steel pipes) are divided into furnace welded pipes, electric resistance welded (resistance welded) pipes and automatic arc welded pipes due to different welding processes. Due to different welding methods, it is divided into two types: straight seam welded pipe and spiral welded pipe. The shape of the end is divided into round welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded steel pipes are welded from steel plates rolled into tubular butt seams or spiral seams. According to the manufacturing method, it is divided into welded steel pipe for low pressure fluid transportation, spiral seam electric welded steel pipe, straight coil welded steel pipe and electric welded steel pipe. Seamless steel pipes can be used for liquid pressure pipelines and gas pipelines in various industries. Welded pipes can be used for water supply pipes, gas pipes, heating pipes, power pipes, etc.

seamless vs welded pipe:

Different uses: seamless steel pipes are mainly used as pipelines or structural parts for fluid transportation, mainly in the machinery industry, while seamed 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 piping. The price of seamless steel pipe is higher than that of seamed steel pipe.

The maximum working pressure that the seamed pipe can generally withstand does not exceed 20 kg, which belongs to the scope of safe use. Generally used for low pressure fluids such as water, gas and compressed air.

The seamless steel pipe can withstand ultra-high pressure, of course, its wall thickness will increase accordingly, and it needs to be designed according to the pressure requirements. Generally used for high temperature and high pressure equipment such as high pressure oil pipes and boiler pipes. 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. The welds are annealed so that the residual stress of the welds is equivalent to that of the base metal, and the pressure range is basically equivalent to that of seamless steel pipes. can also be considered.

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

Read more ：seamless carbon steel pipe

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