Views: 3 Author: Site Editor Publish Time: 2020-07-09 Origin: Site
Analysis of the reasons why double-sided submerged arc straight seam steel pipes are widely used:
(1) Since it is a straight weld, the weld is short, so the chance of defects is small.
(2) The welding seam is a straight line, which has little effect on the coating of anticorrosive materials.
(3) There is basically no residual stress after pipe expansion to eliminate stress.
(4) Staggered edges, slits, pipe diameter and other circumferences are easy to control and excellent welding.
(5) There is no unwinding process, so that the base material has less dents and scratches.
(6) After expanding the diameter, the geometric accuracy of the steel pipe is improved, which greatly facilitates welding on site.
Straight seam submerged arc welded steel pipes are widely used for laying pipelines for transportation of petroleum, natural gas, etc. With the development of welding metallurgy technology and welding material production technology, the materials that can be welded by submerged arc welding have developed from carbon structural steel to low alloy structural steel, stainless steel, heat-resistant steel and so on.
In the construction of long-distance pipelines, pipeline steel pipes account for a considerable proportion. In general, pipeline steel pipe investment accounts for about 35% to 40% of the total project investment. How to choose the pipe with reasonable price and excellent performance is particularly important. The reasonable choice of pipe has a very important impact on saving construction investment, facilitating construction and operating the pipeline system. Long-distance oil and gas pipeline steel pipes include high-frequency straight seam resistance welded steel pipes, spiral submerged arc welded steel pipes, and straight seam submerged arc welded steel pipes. The diameter range of the high-frequency straight seam resistance welded steel pipe is limited, and it is generally limited to steel pipes within Φ406.4mm in China. There are two types of pipe making for large diameter: spiral submerged arc welding and straight seam submerged arc welding. Spiral welded steel pipe has many shortcomings due to its pipe making process and forming characteristics, and its proportion in long-distance pipelines is gradually decreasing. At present, my country has banned the use of spiral submerged arc welded steel pipes as steel pipes for main lines. Straight seam submerged arc welded steel pipes are widely used in long-distance oil and gas pipelines due to their unique advantages.