Electric resistance welded pipe (ERW) is manufactured by cold forming steel sheets into a cylindrical shape. Electric current is passed between the two edges of the steel, bonding the edges together without the use of welding filler materials.
The following steps are required in the manufacturing process
Raw material preparation: Select the appropriate steel strip coil and check the quality, size and chemical composition of the steel strip.
Uncoiling: Unroll the rolled steel strip.
Leveling: Straighten and flatten the steel strip through a leveling machine to eliminate the bending and wavy shape of the steel strip.
End trimming: Trim the two ends of the steel strip to ensure alignment during welding.
Forming: The steel strip is gradually bent into a tube by a forming machine.
High-frequency resistance welding: The resistance heat generated by high-frequency current passing through the contact point is used to instantly heat the edge of the steel strip to the welding temperature and pressurize it to achieve welding.
Deburring the internal and external surfaces of the weld: Deburring the internal and external surfaces of the weld is removed by a special device to ensure the quality of the weld and the smoothness of the inner wall of the steel pipe.
Weld heat treatment: Appropriate heat treatment is performed on the weld to improve the structure and performance of the weld.
Sizing and shaping: The diameter and shape of the steel pipe are accurately adjusted and shaped by the sizing machine.
Nondestructive testing: Ultrasonic, eddy current and other nondestructive testing methods are used to check the quality of the steel pipe weld and pipe body.
Cutting and finished product inspection: The steel pipe is cut to the specified length and the final quality inspection is carried out, including appearance, size, performance and other aspects.
