Hot Tapping is the ability to safely tie into a pressurized system while it is on stream and under pressure. A typical Hot Tap installation consists of a tapping saddle, gate valve, and Hot Tapping Machine.
The Hot Tap cutter is advanced through the valve, to the pipe. The machine is engaged and the cut begins. When the cut is finished, the machine is disengaged and retracted beyond the gate of the valve. The valve is closed and the machine is removed. The coupon is retained by using a wired pilot drill. The wire on the pilot toggles, thus catching the coupon and preventing it from falling off.