Difference Between ERW and UOE Steel Pipes

Straight seam welded steel pipe is divided into high frequency resistance welding and submerged arc welding according to the welding process. Straight seam submerged arc welding is referred to as UOE, and straight seam high frequency resistance welding is referred to as ERW. Compared with submerged arc welding, the BERW process does not add any welding materials during the welding process, and the welding seam is formed without thermal melting, but the welding metal is recrystallized. Therefore, the chemical composition of the welding seam and the base metal is completely consistent 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, so the comprehensive mechanical properties of the ERW steel pipe are better.

Straight seam submerged arc welding (UOE steel pipe) uses the cold expanding process after welding to expand the pipe, so the geometric size of the UOE steel pipe is relatively accurate. The quality of the joint when using the UOE steel pipe is good to ensure the welding quality. Eliminates some internal stresses. 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 during welding, and has a small impact 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, it is expensive qualified, making users with tight funds discouraged.

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.

The 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 production diameter is 1422mm.

2. Welding difference
No welding wire is required for ERW steel pipes; welding wire is required for UOE steel pipes.

3. Appearance difference
The inner and outer welds of ERW steel pipes need to be removed, which is beneficial to corrosion protection; leaving excess welds on the inner and outer walls of UOE steel pipes is not good for corrosion protection.

4. The difference between purchase cost and difficulty
The purchase cost of ERW steel pipes is low, and the cost of UOE steel pipes is very high, and the general price difference is 15% -25%. There are fewer domestic manufacturers of UOE steel pipes, which makes procurement difficult. When the diameter is less than 406mm, the difference in purchasing costs is even greater. There are many manufacturers of ERW steel pipes and the
procurement difficulty is low. When the diameter is less than 406mm, 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-cold areas, and land types II, III, and IV.