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Simultaneous underwater repairs on two offshore vessels in Mexico


Hydrex divers performed underwater thruster operations on two vessels simultaneously in Coatzacoalcos, Mexico. Repairs were carried out on both azimuth thrusters of an FPSO while the thruster seals of a heavy load carrier were replaced.

Both vessels, managed by the same company, were suffering from leakage problems on their propulsion systems.

The stern thruster tunnel of the heavy load carrier was sealed off with our flexible mobdocks. All water was then emptied from the tunnel, creating a dry workspace around the thruster unit. A full inspection of the unit revealed that all blade and shaft seals were leaking. Divers first replaced the four blade seals. The three shaft seals were then replaced in cooperation with the representative of the OEM.

The other vessel was an FPSO which had suffered a problem in the oil distribution box of one azimuth thruster. A special cofferdam, designed by Hydrex R&D department, created a dry environment around this part of the thruster and enabled a repair without removing the thruster. The other azimuth thruster had more serious problems and a complete removal was required – as the thruster was not designed to be removed underwater, a custom procedure was developed.


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