With the continuous progress of science and technology, the production process of steel pipes in various countries has also been significantly improved. At present, the common steel pipe mainly has two forms, which are welded steel pipe and seamless steel pipe. Common steel pipe mainly has welded steel pipe and seamless steel pipe two forms, in the process of engineering construction, will be combined with the specific construction situation to choose the appropriate steel pipe, and the cost as the primary factor. Therefore, this paper from the performance of steel pipe, technology and discrimination methods to distinguish welded steel pipe and seamless steel pipe, hoping to provide reference for the selection of steel pipe in the process of engineering construction.

 A Welded steel pipe is generally a steel strip or steel plate under the action of external force, make it into a round or square, and then weld the surface joints, thus forming a welded steel pipe. The commonly used processes are arc welding, high or low frequency, cold rolling and so on, but the use of these processes for welding will lead to welded steel pipes. At present, according to the shape of welding seam can be divided into straight seam and spiral welded steel pipe, but the two use different technology. The spiral steel pipe is welded by submerged arc welding, which has the advantages of high welding efficiency and less dust. For high frequency or low frequency welding, mainly based on the principle of electromagnetic induction, due to the ac charge in the conductor will occur adjacent and turbine heat effect, can achieve the welding edge of steel to melt state, the final completion of welding. Seamless steel pipe is mainly a solid tube billet or steel ingot for perforation, made of wool tube, and through hot rolling, cold rolling, cold drawing and other processing, and then formed seamless steel pipe. Since seamless steel tubes contain a members section, this hollow section can be used as a conduit for transporting fluids.

The difference is that

First, different materials

1, welded steel pipe: welded steel pipe refers to the steel belt or steel plate bending deformation into a round, square shape and then welded into the surface of the joint steel pipe, welded steel pipe blank is steel plate or strip.

2, seamless steel pipe: made of the whole metal, no joint on the surface of the steel pipe, known as seamless steel pipe.

Two, different uses

1, welded steel pipe: can be used as water gas pipe, straight welded pipe for high pressure oil and gas transmission; Spiral welded pipe is used for oil and gas transportation, pipe pile, bridge pier and so on.

2, seamless steel pipe: used as petroleum geology drilling pipe, petrochemical cracking pipe, boiler pipe, bearing pipe and automobile, tractor, aviation high-precision structural steel pipe.

Three, classification is different. 

1. Welded steel pipe: according to different welding methods, it can be divided into arc welding pipe, high frequency or low frequency resistance welding pipe, gas welding pipe, furnace welding pipe, Bandi pipe, etc. It is divided into general welding pipe, galvanized welding pipe, blowing oxygen welding pipe, wire casing, metric welding pipe, roller pipe, deep well pump pipe, automobile pipe, transformer pipe, electric welding thin-wall pipe, electric welding special-shaped pipe and spiral welding pipe.

2, seamless steel pipe: seamless pipe is divided into hot rolled pipe, cold rolled pipe, cold drawn pipe, extrusion pipe, pipe jacking, etc. According to the shape of section, seamless steel tube is divided into round and special-shaped, special-shaped tube has square, oval, triangle, hexagonal, melon seed, star, winged tube and a variety of complex shapes. The maximum diameter is 650mm and the minimum diameter is 0.3mm. According to different uses, there are thick wall pipes and thin wall pipes.

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