The pump is running , off the best effiency point & almost less than 50 % capacity of its designed all the time.
The thrust went on increasing & the pump was tripped at the tripped seating 0.62mm.
At suction piping there is a immediat elbow on the pump flange, the first stage impeller is double suction, the pump is ballance opposed configeration & is 5 stage. The design flow is 4000M3 per hour.
The pump have this problem since commessioning & almost for last Three years.
There are three more identical pumps side by side but all other three pumps do not have this problem. They are also running almost at 50 % capacity since commessioning & last 3 years.
Can some body put a light on it?