At present, tubes are manufactured inone line that is equipped with following equipment

• Rotary hearth furnace
• Vertical piercing press
• Piercing mill (elongator)
• Pilger mill
• Circular hot saw to sawing tube ends
• Reheating push furnace
• Sizing mill
• Straightener with hyperbolic rolls
• Heat treatment continuous furnace
• Finishing shops for tube finishing and inspections including hydrotest equipment and ultrasonic nondestructive inspection

Principle of tube rolling by pilger mill process

The tube manufacture by pilger method has in our company long years tradition. Already in 1890, the first thin wall tube was manufactured here using this rolling method.

The principle of seamless tube manufacture by pilger method consist in piercing of heated ingot or billet in piercing press (into hollow with bottom) and this hollow is pierced and elongated in piercing mill using cross rolling method into shell (without bottom). The shell is put on on pilger mandrel and is rolled in longitudinal direction in rolls with continuously varying diameter of groove. This rolling is discontinuous (step forward, step backward). After sawing the ends off, the tubes are reheated and sized in longitudinal direction in two high stand to obtain precise outside diameter and roundness.

After cooling, the tubes are transported into finishing shop to make required inspections, tests, end finish, marking and shipping.

Tube manufacture chart - here