Matters needing attention when using straight seam steel pipe

Straight seam steel pipe is a welded steel pipe in which the weld seam is parallel to the longitudinal direction of the steel pipe. It is usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on. Compared with the seamless steel pipe, the production process of the longitudinal welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid.

Straight seam steel pipe is widely used in petroleum (such as octg pipe), metallurgy, construction, coal mine, port, machinery and other industries. The installation and use of straight seam steel pipes have strict technical requirements, and they should be operated simultaneously according to the actual situation to ensure the quality. In normal use, the straight seam steel pipe should pay attention to the following points:

Straight seam steel pipe installation

Position the pipes according to the design of the drawings, prefabricate the pipe supports according to the site conditions, then design and cut on site as needed, chamfer with a polishing machine, and then weld.

Quality requirements for straight seam steel pipes

1. The deviation per meter for horizontal installation should be less than 1mm, and the deviation per meter for vertical installation should be less than 3mm.

2. Avoid welding branch pipes and elbows at the welding place.

3. The weld seam is required to be straight and full, and there is no burn-through or crack on the weld seam surface.

There are strict technical requirements in the equipment application process of straight seam steel pipes, which must be carried out in the pipeline. According to actual conditions and operating specifications, ensure the safety and quality of straight seam steel pipes. So what should be paid attention to when using straight seam steel pipe equipment?

The pipe trenches should be dug according to the requirements of the drawings, the pipe wells have been laid with bricks, and the required straight seam steel pipes have been delivered with good quality and passed the inspection. The required construction items including electric welding machine, cutting machine, electric hammer, polishing machine, etc. have been prepared, and only a series of preparatory work is required to make the initial equipment.

Arrange the pipeline according to the drawing plane, prefabricate the pipeline support according to the site situation, then cut the material according to the plan and site, then grind the groove with a grinder, and then weld. During the welding process, the strip is fed to the welded pipe unit. After several times of rolling, the strip steel is gradually rolled into a round tube blank with an open space. Adjust the shrinkage of the kneading roller to control the gap between the welds at 13mm, and make the two ends of the welds flush. If the open space is too large, the effect of adjacency will be reduced, eddy currents will be lacking, and the weld will not weld or crack due to poor intergranular joints. If the open space is too small, the proximity effect will increase, and the welding heat will be too large, causing the weld to burn; after kneading and rolling, the weld may form deep pits, which will affect the surface quality of the weld.

It is not allowed to weld the branch pipe at the weld seam, and avoid the weld seam at the elbow. The error per meter of the vertical equipment riser should be less than 3 mm, and the error of the horizontal equipment riser should be less than 1 mm. The surface quality of longitudinally welded pipes should be smooth, and defects such as wrinkles, cracks, delamination and lap welding are not allowed. Small defects on the surface of straight seam pipe (such as scratches, scratches, misalignment of welds, burns and scars) must not exceed the negative error of wall thickness.

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