In Double/Twin screw pumps, the variety of parts is more than Triple screw pumps. The main damage in this model of screw pumps is related to the timing gears. Power is transferred from the driving screw shaft to the driven screw shaft through these timing gears. It is very important to monitor the condition of the gears and carefully check the temperature, oil level, vibration and sound of the gears. In such a way that the smallest problem in the operation of the gears leads to the loss of the buoyancy of the screws, and the direct result is severe wear of the flankes of the screws and their destruction. Refurbishment of screws and coating of screw crowns, reconstruction of the main cylinder wall and reconstruction of the mechanical seals are the most important processes of reconstruction and repair of this model of screw pumps.