This document consists of the detection and verification of a failure in the area of sea water pump of a Yanmar 6HAL2-DTN Auxiliary Engine no1 with 439800 running hours. Trend line was drawn using the sea water pump pressures from the engine sea trial record.
The sea water pump condition is based on the pressure readings taken during the engine operation. The data obtained from the engine analysis was processed, analyzed and compiled by a qualified professional analyst, resulting in the following recommendation:
Sea water pump condition has to be checked.
2.1 THEORETICAL REFRENCES:
Low pressure of the sea water pump indicates a problem of excess clearance or damage on the impeller running surfaces.
2.2 VIBRATIONS SHOWN
Pressure measurements acquired can be shown as follow:
The sea water pump pressure is much lower than the pressure from the sea trials. As a conclusion of this analysis, it was recommended to check the sea water pump condition.
3 SHIP ENGINEERS CHECKS
The engine has been shut down then the sea water pump was disassembled to access the pump impeller. The clearance on the impeller was measured and was found to be substantial. For this type of sea water pump clearance on the running surface of the impeller should be between 0,20[mm] and 0,50 [mm]. The pump impeller has been replaced with a new one. Pump bearings and mechanical seals were also replaced.
After the pump reassembly was made the engine was started with the overhauled sea water pump and new measurements were taken the results can be shown as follow:
It is clearly shown that the sea water pump pressure is in the sea trials limit.
It can be concluded that the diagnosis obtained from the measurements and the data analysis was correct.