System for supplying lubricant, apparatus for manufacturing seamless pipes or tubes, and method of manufacturing seamless pipes or tubes

An apparatus for manufacturing a seamless pipes or tubes, comprising:

• a piercing mill including a plug oriented in a piercing direction, a pair of disc rolls disposed on both sides of an axis of the plug in a first plane including the axis, and a pair of main rolls disposed on both sides of the axis with a predetermined inclination to a second plane including the axis and orthogonal to the first plane;
• and
• a system for supplying a lubricant including a storage tank of the lubricant to be supplied to the disc rolls, a plumbing extending from the storage tank to a position near the disk rolls, a spray nozzle provided at the tip of the plumbing, a device for switching flow direction provided in some midpoint of the plumbing, a plumbing extending from the device for switching flow direction to the storage tank, and a device for releasing pressure in the plumbing to the storage tank while the piercing mill is not at work, the pressure releasing device provided between the device for switching flow direction and a spray port to the disc rolls of the plumbing.