Tubes are manufactured from mild steel strips, slit from Cold Rolled Low Carbon Steel coils. The strip passes through a series of drive forming and fin rolls and takes the required circular shape and is welded continuously by passage of an electric current of high frequency i.e. 4, 50, 000 cycles/second across the abutting edges.
The tubes thus formed and welded pass through the sizing sections where dimensional deviations if any are corrected before the tubes are cut into required length by automatic cutting machines. The tubes are then end deburred and pressure tested. Thereafter protective surface finishing operations such as hot dip Galvanizing or varnishing is done as per specific requirement. The tubes are offered as plain, beveled, threaded ends or with flanges.
HR Coils are slitted to predetermined widths for each size of tube.
Slitted coils are initially formed into U shape and then into a cylindrical shape with open edges using a series of forming rolls.
After water quenching, slight reduction is applied to tubes with sizing rolls to give them desired accurate outside diameter.
Precision tubes are cut to required lengths by flying cut off disc/saw cutter.
The precision tubes ends are faced and bevelled by the end facer.
All the processes are continuous with auto arrangements. These plain ended tubes go for further processing as per the customer need like galvanizing, threading, black varnishing etc.