ERW and SAWL steel pipe
Straight seam welded steel pipe, according to welding process can be divided into high frequency resistance welding (ERW Steel Pipe) and submerged arc welding (SAWL Steel Pipe), longitudinal submerged arc welded is short for SAWL, high-frequency straight seam resistance welding is short for ERW.
High frequency resistance welding steel pipe (ERW steel pipe) because of its welding and submerged arc welding in the welding process, ERW process does not add any welding materials, welding without heat melting state of weld metal, just after the recrystallization process, the formation of the weld and base material chemical composition completely.
Consistent, steel after annealing treatment, manufacture of cold molding stress, welding stress were improved, therefore the comprehensive mechanical properties of ERW steel pipe.
Longitudinal submerged arc welding (SAWL steel) because it uses the welding cold expanding process pipe, so the SAWL pipe dimension precision, using SAWL steel pipe butt counterparts in good quality so as to ensure the welding quality, through expanding technology to some extent by removing a portion of the internal stress. In addition SAWL steel pipe.
Welding multiple wire welding (three wire, the four wire), such that the welding process generated when welding line energy is small, the parent material of heat affected zone of influence degree is small.
Multiple wire welding after welding of former wire can rise to eliminate welding stress effect, thus the mechanical properties of steel pipe
The improvement of the mother can do by ultrasonic flaw detection of plate 100%, meet the high pressure pipeline of parent material requirements.
Although the SAWL pipe performance better than other steel tube, but its high price, make capital tension to the user and step back.
One, raw material and production capacity difference
ERW steel is the raw material of hot rolled steel coils, SAWL pipe material is hot rolled steel plate.
So ERW steel can achieve continuous assembly line operation, high production efficiency, low production cost; and SAWL steel is steel plate processing, can realize continuous production line operation, low production efficiency, high production cost.
Two, application difference
ERW pipe is mainly used in natural gas, crude oil, refined oil, pulp and other terrestrial long distance transmission pipeline.
SAWL steel is mainly applied to high-voltage undersea pipeline, alpine region, land two or three, area four class