Case Study on Catastrophic Failure of the Cooling Water Pump DE Bearing

Abstract

Abstract Case study on Catastrophic Failure of the Cooling Water Pump DE Bearing due to High vibration and Flow turbulence. The Cooling water pumps are the core unit in the Gas separation plant for cooling the Condenser during gas separation process and these pumps are required in operation 24/7. This case study represents the Catastrophic Failure of the Cooling Water Pump DE Bearing assembly due to High vibration and Flow turbulence within 90 Days from the commissioning. The function of a cooling system is to remove heat from processes or equipment. Heat removed from one medium is transferred to another medium, or process fluid. Most often, the cooling medium is water and the same get cool into ambient temperature when passes through the Cooling tower. In Oxygen gas production cooling water is circulated into the Surface condenser to remove the head during gas separation. High-capacity cooling water pump (6000 m3/hr.) plays an important role for continuous circulation of the cooling water in the closed loop. During operation, a sudden increase in Pump B DE bearing temperature and immediately the pump tripped due to high current. During site inspection we found the DE Bearing housing was cracked and Pump rotor was shifted towards the Motor. We have noticed the peaks at 1x, 7x & 14x in the FFT Spectrum along with Raising Floor noise which give the sign for the Flow turbulence/cavitation and VP Frequency. Additionally, inspection on the Pump internals and other parameters was checked.DE bearing was completely damaged condition.DE Mechanical seal was also damaged condition.Found there was VPF and turbulence in the vibration spectrum.The Suction and Discharge piping was inspected, and suction isolation (Butterfly valve) position was shifted from Vertical to Horizontal for operator convenience. Performed Butterfly Valve flow pattern using the software tool and found the most recommended pattern is vertical. Flow turbulence could occur if the Butterfly valve is in Horizontal position as this is Double suction pump. The suction piping with necessary Valves and fittings needs to be designed & installed as per Pump OEM recommendation as it is important for the Pump to operate without any interruption. The Valve position is also very important and if any changes at site and the same required approval from the OEM.