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Electric Resistance Welded (ERW) Tube Making Process

Below is a general description of Webco's ERW tube-making process. Inquire for more detail on Webco's extensive engineering, customization, testing, and quality-control capabilities.

Process
Description of Manufacturing and Testing Process

Raw Material: Slit Coils

Webco purchases prime sheet coils from the approved steel suppliers that conform to Webco's raw material specification requirements.

Coil Slitting

(Coil Slitter)

 The coil is slit to planned width while maintaining lot traceability to supplier's heat number and coil number.

Tube Forming

(Roll Forming Tube Mill)

Continually forms the slit coil to tubular shape through series of forming and fin rolls. Mill tooling is designed by our engineering group to perform consistent dimensional control and result in optimum welding condition.

Welding

(HF & LF Welder)

Both edges are welded continuously using high frequency or low frequency electric resistance induction welding method.

Flash Removal

(Flash Cutting Tool)

Due to the upset work during welding process, a small amount of metal will be extruded from the upset edge. This squeezed metal, called weld flash (or weld bead) will be removed by specially designed cutting tool from the inside and outside of the tube.

In Process Non-Destructive Electric Test

(Ultrasonic Tester)

Conduct in process non-destructive inspection on weld area using ultrasonic testing method to detect any possible weld discontinuities to ensure the quality of the weld.

Sizing

(Roll Sizing Mill)

Through sizing roll section of the tube mill, tube outside diameter will be reduced slightly and size to final outside diameter dimension. Outside dimension can be maintained to a half industrial standard for special application.

Cut to process or finished Length

Cut-off M/C

 Cut to the process length or mill finished length depend on the requirements from the customer.

Inspection

 Dimensional inspection and process destructive testing is conducted. Destructive testing includes a flattening test and a reverse flattening test, which are both conducted to monitor the soundness of the weld.

Heat Treating

(Roller Hearth Furnace)

 Unless the specification calls for finishing in as welded condition, tubes will be heat treated (normalized) in a controlled atmosphere continuous furnace and cooled in air.

Straightening

(Two Plane Straightener)

The tube is straightened longitudinally in vertical and horizontal planes through a series of offset rolls achieving a straight tube with a minimal degree of cold work. Straightness can be maintained to a half industrial standard for special application.

Final Non- Destructive Electric Test

(Eddy Current or Ultrasonic Tester)

100% inspection of the tube by the industrial test specification or special customer testing specification with eddy current or an ultrasonic non-destructive electric test method.

Length Cut and End Finishes

(Cutting and End Finishing Equipment)

 Tubes are cut to the finished length and the ends finished, with options such as de-burring or OD/ID chamfering available. If required, the tubes will be stenciled with specified information. The tubes will be bundled in hex shape with proper lot identification information.
Inspection and Testing
 Final dimensional inspection and destructive testing (if required) is performed. If any mechanical property or other special testing is required, a proper sample will be collected for further testing at the metallurgical testing lab.