Tube manufacturing

One of the most common form of tube manufacture is longtitudinal forming where the coil, line concept is employed

Raw material
The raw material is cold- or hot rolled Stainless steel coils. The coils are sheared in strips with the width and thickness that correspond to the final dimension of the tube.

Forming and welding
The strip is set up in a decoiler, and feeded into a forming and welding line. The strip is formed by rolls to a tubular form before the edges are welded together with multiple TIG or Plasma torches. TIG and Plasma is continously replaced with Laser welding, LBW.

Shielding gas
Argon or Helium and additions of Hydrogen are used as welding and shielding gas.

Filler metal
Standard grades and thin walled special grades are welded without filler metal.
Special grade pipe are welded with over alloyed filler metal in order to fulfill the specification.

The tube is tested with Eddy Current in the welding line and/or in a separate line.

Bead working
Most of the TIG- and Plasma welded tubes with OD < 114,3 mm are bead worked in the welding line.

Heat treatment
When required, the tubes are heat treated in-line in an open or bright atmosphere, or in a separate open furnace.

After heat treatment the tubes are straightened.

All tubes are pickled or bright.

Inspection and testing
The tubes are tested, marked and inspected according to the required standards. 

Dimension range, Tubes welded from coil