Gearbox leveling on a ship or FPSO 1

[rQuestionEngineering]

Is it required to repeat leveling check and adjustment for gearbox installed on a ship ?
Everything was adjusted and test run from the factory and released for site installation.

Link

 

[TugboatEng]

Yes, installation error could cause distortion of the gearbox case and misalignment leading to failure. This is so critical that it's standard practice to check the gearbox after installation AND after launching and ballasting the vessel if the install was done in drydock or outside of normal operating parameters.

If the foundation is sufficiently rigid and resilient mounted the second check may not be necessary but my experience is that most manufacturers won't begin warranty without a field verification. Your class society may also require it.

 

[rQuestionEngineering]

GB foundation check and GB deflection check after launching onto water will not be valid because it is not possible to have the precision level keeps moving. Is this a fact or a myth ?

 

[Artisi]

In a marine installation the check is the coupling alignment between the driver and the gearbox and the coupling alignment between the gearbox and the driven component, it has nothing to do do with levels.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[TugboatEng]

The contact pattern also needs to be checked as gearboxes can twist.