CRANKSHAFT FAILURE OF SHIPBOARD HYDROBLASTER
25th April 05
The Hydroblaster was placed onboard for forepeak tank derusting and painting. Riding team was there to do the job. A 60 kw motor drove the pump shaft at tremendous rpm to produce 400-500 bars at nozzle for rust removal.
The "stuffing box" of this kind of p/p is prone to leaks. The Riding teams would work 12-14 hours a day and the p/p was being overworked. When the stuffing box leaked, there were tell-tale holes in the bottom to indicate which unit out of the three was leaking.
The Camshaft runs on roller bearings inside a gearbox filled with T-78 turbine oil.
In one situation, the stuffing box of one of the units was leaking and because the 2/E was busy elsewhere due to hectic schedule of the ship, it was decided that the repair would be done later and till that time the leaks were channeled into the forepeak itself. One of the Polish riding gang was too bothered by the leak and he decided to plug the 10 mm tell-tale hole by pushing in a grease nipple. The leakage water found its way into the gearbox, emulsified the turbine oil level, but was not noticed.
After stopping for the night when next morning it was switched on, the camshaft was already seized on to the bearing. The strong motor still tried to move the shaft, shearing the camshaft into two.
Effects :- 1. Repair quoted price: USD 5000/-
2. Polish team replaced by Indians.