Process Difference between Spiral Steel Pipe and Straight Seam Welded Pipe

Press Release : November 10, 2020
Process Difference between Spiral Steel Pipe and Straight Seam Welded Pipe

Spiral steel pipes and straight seam steel pipes are welded steel pipes. They are widely used in the transportation of liquids in various industries such as water supply, heating, and oil and gas transportation. They have different production processes and have different advantages in different applications. Then, they What are the specific differences?

Welded steel pipes refer to steel pipes with seams on the surface that are welded by steel strips or steel plates that are bent into round or square shapes. The blanks used for welded steel pipes are steel plates or strip steels. It can be divided into straight seam welded pipe (ERW, LSAW) and spiral welded pipe (SSAW).

Spiral steel pipe is a spiral seam steel pipe made of strip steel coils as raw materials, often extruded and formed by automatic double-wire double-sided submerged arc welding. The spiral steel pipe feeds the strip steel into the welded pipe unit. After rolling by multiple rollers, the strip steel is gradually rolled up to form a round tube blank with an open gap. The reduction of the squeeze roller is adjusted to control the weld gap at 1~ 3mm, and make both ends of the welding joint flush.

Main technological characteristics of spiral steel pipe:

a. During the forming process, the steel plate deforms uniformly, the residual stress is small, and the surface does not produce scratches. The processed spiral steel pipe has greater flexibility in the size and specification range of diameter and wall thickness, especially in the production of high-grade steel-grade thick-walled pipes, especially small and medium-diameter thick-walled pipes. It has advantages that other processes cannot match, and can satisfy users. More requirements on spiral steel pipe specifications.
b. Adopting advanced double-sided submerged arc welding technology, welding can be realized in the best position, and it is not easy to have defects such as wrong edge, welding deviation and incomplete penetration, and it is easy to control welding quality.
c. Perform 100% quality inspection on steel pipes, so that the entire process of steel pipe production is under effective inspection and monitoring, which effectively guarantees product quality.
d. All equipment of the entire production line has the function of networking with the computer data acquisition system to realize instant data transmission, and the central control room will control the technical parameters in the production process.

The strength is generally higher than that of straight seam welded pipes. A narrower blank can be used to produce welded pipes with larger pipe diameters, and the same width of blanks can also be used to produce welded pipes with different pipe diameters. But compared with the straight seam pipe of the same length, the weld length is increased by 30-100%, and the production speed is lower. Therefore, most of the smaller diameter welded pipes adopt straight seam welding, and the large diameter welded pipes mostly adopt spiral welding.

Spiral seam welded steel pipes are divided into automatic submerged arc welded steel pipes and high frequency welded steel pipes.

a. Spiral seam automatic submerged arc welded steel pipes are divided into two types: Class A pipe and Class B pipe according to the pressure of the conveying medium. Class A pipes are generally welded with ordinary carbon steel Q235, Q235F and ordinary low-alloy structural steel 16Mn; Class B pipes are welded with steels such as Q235, Q235F, Q195, etc., and are used as low-pressure fluid conveying pipes.

b. Spiral seam high-frequency welded steel pipes currently have no unified product standards. They are generally made of ordinary carbon steel Q235, Q235F and other steels.

Straight seam pipe refers to a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. It is also generally called straight seam welded pipe or straight seam steel pipe. The straight seam pipe is formed by rolling a certain specification of a long steel strip through a high-frequency welding unit and welding it with a straight seam. The specifications of straight seam pipes are expressed by their nominal diameters. According to the wall thickness, they can be divided into thin-walled straight seam pipes and thick-walled straight seam pipes. According to the shape, it can be divided into round, square or special-shaped tubes. The production process is simple, the production efficiency is high, the cost is low, and the development is fast.

Straight seam pipes are mainly used in water supply engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction. Used for liquid transportation: water supply and drainage. For gas transportation: coal gas, steam, liquefied petroleum gas. For structural purposes: as piling pipes and bridges; piers, roads, building structures, etc.

Tips: ASTM A53 covers seamless and welded steel pipe with nominal wall thickness. The surface condition is usually black and hot-dipped galvanized. ASTM A53 is produced mainly for pressure and mechanical applications, and is also used for transport of steam, water, gas line pipes.

ASTM A53 Grade B is the material under the American steel pipe standard, API 5L Gr.B is also the American standard material, A53 GR.B ERW refers to the electric resistance welded steel pipe of A53 GR.B; API 5L GR.B Welded refers to the material Welded steel pipe of API 5L GR.B.

Notes to editors

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