Bowthruster |
It was noted that of 8 anodes fitted in this space, 7 had no remaining anodic material. The final anode was severely depleted.
The ropeguard was damaged by corrosion and the effects of cavitation and turbulence
The Support tube was pitted to a depth of 20 mm on the blade facing face.
This damage in particular was carefully examined to ensure that there were no structural strength or stress raiser issues
The adjacent areas to the blades on the tunnel were pitted and evidence of grooving either side of a circumferential weld.
Repairs
The areas were grit blasted to allow further inspection. This revealed that there was sufficient depth of material remaining to allow repairs to be carried out. Shown is an area on the Tunnel adjacent to the blades after blasting and part coated with repair productAfter further cleaning and friable material removal Belzona 1111 was applied to the damaged support tube and tunnel areas. An overlap of around 50mm was given to ensure that any edge lifting would not affect the main repair.
The initial application concentrated on ensuring full contact with the base material by forcing small quantities of product into the pits removing any air bubbles. The main layer was then built up on top of this.
Cleaning of tools was made possible by use of a release agent Belzona 9111
Notes were made to specially inspect the damage at next docking. Were edge lifting is evident it is possible to cut back the damaged areas and overlay again with Belzona 1341.
The shaft seal landing face was machined to remove a grove formed by rub of the two parts. The blade palms were inspected and no significant damage noted. All seals were replaced and new anodes and ropeguard fitted.
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