Motion on FPSO. How Does it affect the rotating machinary.

[MechanicalGraduate]

Hi All,

How does the motion on FPSO affect turbine, pumps, lube oil system?.

Are there considerations we should take into account when selecting the rotating machinery?.

Regards,

Mechanical Graduate.

 

[pennpiper]

Well??? Lets see if we can figure this out logically?
Jet Engines are a form of turbine.
Jet Engines are classified as a piece of rotating machinery
Jet Planes have lots of pumps and lube oil systems
Jet planes are subject to lots of motion
Fighter jets are subjected to very complex twists and turns
So? Does the motion of high performance aircraft have a serious negative effect on the Turbines , pumps or lube oil systems?
The considerations you should take in to effect for a FPSO pump would be the same considerations you would have for an onshore pump.
What considerations do you use for an onshore pump?




prognosis: Lead or Lag

 

[moltenmetal]

The motions of an FPSO do affect many aspects of the design of not just rotating equipment, but even "static" stuff like piping. Depending on what you're planning to do on that FPSO, that can make doing it a hell of a lot more complicated than it would be to do the same thing on terra firma- even to the point of rendering that idea "dead in the water".

But remember, an FPSO has at least one big piece (or many smaller pieces) of rotating equipment on it- to drive the screws. So it is possible. People who build rotating equipment for offshore use know how to deal with it.

 

[lsrisurya]

very good question Mr.MechanicalGraduate,

Greetings for the day


Finally,Motion of FPSO will be effecting Rotating machines and Piping or not ?Anybody can explain me in details ?
I want to know what is average or ideal speed of FPSO when floating based on turret?

 

[Pumpsonly]

The motion of FPSO caused by the wave will affect all equipment. The wave action will rock the FPSO left and right, up and down.These movements cause acceleration and deceleration of the equipment and imposing extra load on its foundation and anchoring due to the inertial of the equipment. Very often these days, equipment vendors are required to carry a seismic study on the complete package.

 

[LittleInch]

It can affect it by adding some loads due to reaction forces on the spinning shaft not normally seen on fixed foundations and also additional forces on the mounting bolts / locations due to mometum changes of the mass of the item. However, most of these are realtively small and providing you can tell the vendor what the maximum acceleration and velocities are in x, y and z plus any rolling motion, then they will be able to beef up the bearings say or the mounting frame to take account of it, in much the same way as you design for earthquakes, hence the seismic study noted above. The problem arrives if no one tells them and you end up with a bit of kit deisgned to use its mass weight only down and then gets subjected to motion in x and y and rips the mounting bolts off.

It shouldn't have any real affect on the speed of the rotating shaft as normally this is far higher than the movement of the FPSO

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[zdas04]

FPSO's and Drill Ships have VERY precise position-holding ability. They use the same turret-mount screws that are becoming normal on cruise ships. These gadgets rotate the each screw through 360° independently. They also have very complex trim and ballast capability. Finally, they are similar in size to an aircraft carrier. All together this kit keeps the FPSO in a very narrow range of positions in 3D even in bad weather. You approach potential racking by building rigid foundations for the pumps and vessels. These are problems that were discovered and solved in the early steam engines in the 1700's and 1800's. Maritime Engineering standards are pretty mature.

David Simpson, PE
MuleShoe Engineering

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