Spiral submerged arc welding steel pipe and straight seam submerged arc welding steel pipe knowledge

50 ~ 60 s, spiral steel pipe has been widely used in the oil and gas pipelines, 70 ~ 80 s by straight seam submerged arc welding steel pipeand the serious challenge of ERW steel pipe, since the world basically is no longer used in oil and gas pipeline spiral steel pipe, and pipe company has many large international oil company are not allowed to use spiral submerged arc welding steel pipe in oil and gas pipelines. This is because the development of pipeline industry reliability of steel pipe demand is higher and higher, and spiral steel pipe due to its manufacturing itself unable to overcome the defects, make it difficult to meet the requirements of objective development.

Spiral pipe and straight seam submerged arc welding steel pipe compared in terms of quality has certain insufficiency, the following article summarizes seven for your reference.

(1) spiral steel pipe manufacturing process to determine the residual stress is larger, according to foreign relevant data records, some even close to the yield limit, straight seam submerged arc welding steel pipe due to the expanding process, residual stress is close to zero.

(2) the spiral seam welding tracking and ultrasonic on-line detection are more difficult, therefore, weld defects exceeding probability higher than straight seam submerged arc welding pipe.

(3) the most amount of spiral steel pipe welding line fault in 1.1 ~ 1.2 mm, according to international practice 10% to less than the thickness of the wrong side of traffic, such as pipe wall thickness is small, the wrong side of quantity is difficult to meet the requirements, and straight seam submerged arc welding pipe without this problem.

(4) compared with straight seam submerged arc welding pipe, spiral weld line is poorer, the stress concentration phenomenon is serious

(5) spiral submerged arc welding steel pipe heat affected zone is greater than the straight seam submerged arc welding steel pipe, heat affected zone and heat affected zone is weak link welded pipe quality.

(6) spiral seam welded steel pipe geometry size precision, brings to the site construction, such as the counterpart, welding) certain difficulties.

(7) the same diameter, the thickness of the spiral seam welded steel pipe can reach is far less than the straight seam submerged arc welding steel pipe.