HSOS Industrial Services restored the shaft seat of a dredging pump to slide-fit tolerance directly on board a vessel in the Netherlands, including installation of a new water chamber sleeve.
Background
A dredging vessel operating in the Netherlands required urgent attention to the main shaft of its dredge pump. Wear on the shaft seat had progressed to a point where reliable sealing was no longer possible. Transporting the pump to a workshop was not feasible – downtime had to be minimised and the vessel needed to return to service quickly.
Challenge: Precision Machining Aboard a Vessel
Achieving slide-fit tolerances (ISO 286) on a pump shaft at sea demands exceptional tooling, fixturing and alignment control. Any deviation from concentricity results in vibration, accelerated bearing wear and premature failure. HSOS designed and manufactured a purpose-built machining tool tailored specifically to the geometry of this pump, enabling accurate on-site material removal while maintaining true centreline alignment.
Self-Alignment via the Pump's Own Drive
A key engineering decision was to drive the machining tool using the pump's own drive system. This approach guarantees perfect coaxial alignment between the cutting axis and the pump shaft axis – a condition that cannot be reliably achieved when using an independent external drive unit.
New Sleeve Installation
Following precision machining of the shaft seat, a new sleeve was fitted into the water chamber. The sleeve provides the dynamic seal between the rotating shaft and the stationary water chamber housing, and protects the shaft from further erosion by the pumped medium. Wall thickness, material grade and fit were specified according to the operating parameters of the pump, including flow rate, pressure and media characteristics.
Results
- Shaft seat machined to slide-fit tolerance without pump removal
- Custom tool with integral self-alignment using the pump's own drive
- New water chamber sleeve installed
- Entire scope completed on board – no dry-dock or workshop required
- Vessel returned to dredging operations without delay
This project demonstrates how purpose-engineered tooling combined with on-site machining expertise can eliminate costly off-vessel repairs in demanding maritime environments.