A major water utility in Thailand recently awarded a drop-in pump replacement order to PSS. The original pump, a split case BB1 originally manufactured by a major Japanese OEM, suffered a catastrophic failure at site during restart operations. Upon opening the pump in the PSS Pump Repair Center in Rayong, our engineers witnessed severely distorted wear rings, fractured impellers, heavy corrosion on the body, and cavitation. Doing a RCA on this pump was not straightforward – as there were a combination of issues involved like corrosion, cavitation, fluctuating pump operation, etc.
A site survey revealed that the customer was operating the pump with low flow conditions. Due to variations in water demand, it was difficult for the water utility to operate the pumps at BEP, making this a good candidate for a VFD. The data further showed that during the last few months, the deterioration inside the pump caused an efficiency drop of nearly 10% from the performance curve. With a motor size of 1.3 MW, the utility was losing about 130 kUSD per year if they were operating the pump continuously over a period of 1 year.
In addition, a detailed investigation at stie on the pumped raw water showed high levels of chlorides, which accelerated the galvanic corrosion process between the stainless steel impeller and cast iron body. PSS Engineering recommended upgrading the pump metallurgy due to the changing water conditions.
The water utility Maintenance and Engineering team was quite satisfied with our analysis and accepted most of our recommendations. PSS was therefore awarded the contract for an upgraded drop-in pump in place of the Japanese pump. PSS had offered superior delivery times of less than 3 months (typical lead time for these pumps are about 6-8 months) and competitive pricing. PSS further ensured that no modifications would be required on the base plate, piping, and coupling to the 1.3 MW motor as we had done an extensive exercise with our 3d scanners. To further ensure a superior performance of the pumps, PSS will redesign the impeller vanes and diffusers. Finally PSS poposed coating the entire pump with the Enecon range of ceramic composite polymer coatings.