The difference between ERW straight seam resistance welded steel pipe and straight seam submerged arc welded (UOE) steel pipe:
Straight seam welded steel pipe is divided into high frequency resistance welding and submerged arc welding according to the welding process.
High frequency resistance welded steel pipe (ERW steel pipe)
Because its welding process is compared with submerged arc welding, the ERW process does not add any welding materials during the welding process, and the welding seam is formed without thermal melting, but the weld metal undergoes recrystallization. The chemical composition is completely the same. After the steel pipe is annealed after welding, the internal stress of the cold forming process is improved, and the internal stress of the welding is improved. Therefore, the comprehensive mechanical properties of the ERW steel pipe are better.
LSAW (UOE steel pipe)
Because it adopts the cold expanding process after welding to expand the pipe, the UOE steel pipe has relatively accurate geometric dimensions. The quality of the joint when using the UOE steel pipe is good to ensure the welding quality. The internal stress is partially eliminated by the pipe expanding process. In addition, UOE steel pipes are welded by multi-wire welding (three-wire, four-wire). Such a welding process produces a small amount of linear energy and a small degree of influence on the heat affected zone of the base metal. After the multi-wire welding, the welding wire can play a role in eliminating the stress generated during welding, thereby improving the mechanical properties of the steel pipe. The base material can achieve 100% ultrasonic flaw detection of each steel plate, which meets the requirements of high-pressure pipelines for the base material. However, although the comprehensive performance of UOE steel pipe is better than other steel pipes, its high price makes it prohibitive for users with limited funds.
1.the difference between raw materials and production capacity
The raw material of ERW steel pipe is hot rolled steel coil, and the raw material of UOE steel pipe is hot rolled steel plate. Therefore, ERW steel pipe can realize continuous pipeline operation, high production efficiency and low production cost; while UOE steel pipe is processed by steel plate, continuous pipeline operation cannot be realized, production efficiency is low, and production cost is high.
ERW steel pipe is limited by the thickness of the coil. Generally, the maximum thickness that can be produced is 25mm and the maximum caliber that can be produced is 660mm. The maximum thickness that UOE steel pipe can be produced is 40mm. The maximum caliber that can be produced is only limited by the width of the steel plate. The maximum production diameter is 1422mm.
2.the welding difference
No welding wire is required for ERW steel pipe welding; UOE steel pipe requires welding wire.
3.Difference in appearance
Both the inner and outer welds of ERW steel pipes need to be removed, which is good for corrosion protection; the welds on the inner and outer walls of UOE steel pipes leave excess height, which is not good for corrosion protection.
4. Difference between purchase cost and difficulty
The purchase cost of ERW steel pipe is low, and the cost of UOE steel pipe is very high, and the general price difference is 15% -25%. There are fewer domestic manufacturers of UOE steel pipes, making procurement difficult. When the diameter is less than Φ406mm, the difference in procurement costs is greater. There are many manufacturers of ERW steel pipes and the procurement difficulty is low. When the diameter is less than Φ406mm, the purchase cost will be greatly reduced.
5. application differences
ERW steel pipes are mainly used in long-distance land transportation pipelines such as natural gas, refined oil, crude oil, and pulp. UOE steel pipes are mainly used in high-pressure submarine long-distance pipelines, high-altitude regions, and second-, third-, and fourth-class areas on land.