In situ machining of bolt holes for fitting of a new shaft line coupling

The cargo ship M/V Polaris Liberty, a 140-meter-long vehicle carrier, was in dry dock at a shipyard in Klaipeda, Lithuania, for repairs, including the installation of a new hydraulic shaft coupling.

During disassembly, scoring was observed in the fitted bolt holes connecting the intermediate shaft and the coupling.

MarineShaft was brought in to resolve the issue by supplying 14 new bolts for the flange connection and performing in-situ machining of the damaged holes.

We manufactured 14 bolts with dimensions Ø95 x 289 mm, featuring oversized bolt bodies to accommodate the re-machined holes. The bolts were made from 42CrMo4 steel and delivered with a 3.2 LR certificate.

Our portable machining equipment was sent to the shipyard, and two of our service engineers carried out the in-situ machining of 12 bolt holes on the coupling and intermediate shaft flange.

Final machining of the bolt diameters to match the repaired hole dimensions was performed by the shipyard.

The in-situ work was completed within just 3 days.

On-site repair of high-strength fixed-pitch propellers 

We recently completed an on-site propeller repair assignment for a vessel during its
dry-docking at Oresund Drydocks in Sweden.

The vessel was equipped with four fixed-pitch propellers – two aft and two forward – operating under conditions that require highly durable propulsion components.
All four propellers had sustained edge damage.

We mobilized a service team of four certified welders who carried out
manual metal arc (MMA/stick) welding on the high-strength steel propellers,
designed to operate in ice water.

MarineShaft has a wide range of class-approved welding procedures

Our repair scope included:
•    Grinding of the damaged areas to prepare for welding
•    Controlled preheating before welding
•    Welding of new material, shaped to match the original blade geometry
•    Slow cooling to ensure structural integrity and prevent stress
•    Liquid penetrant inspection (LPI) of all welded areas
•    Final inspection and approval by the classification society DNV