Application of Temperature loads for Horizontal Vessel 1

[AlbertStructural]

Dear All,
I am having to design an oil & gas platform structure supporting a vessel equipment. As per the loading table and requirements given by the consultant, we need to input the "Temperature loads".
I was wondering how to do an input for temperature loads? I haven't applied this loading before so need a real help/input from anybody expert in this regard.

I have attached a general sketch of the problem here with for more clarity.

Regards.

 

[thaidavid40]

Is the vessel fixed at both saddles? Usually, vessels "float" on one of the saddles, and are fixed laterally at the other. This float takes out almost all of the thermal expansion stress on the saddles. The only lateral component left would be the weight of the vessel times the frictional coefficient of the bearing contact areas. If the vessel is laterally fixed at both saddles, then I would assume an equal and opposing reaction on each saddle (assuming they have about equal stiffnesses, including their connections and supports).
Dave

Thaidavid

 

[dig1]

Albert,

In my experience one of the saddles is fixed and the other allows movement in the longitudinal direction of the vessel due to thermal expansion. The sliding saddle is also, usually restrained from lateral movement, as is the fixed saddle.

There is s friction force on the sliding saddle due to the coefficient of friction between the base of the saddle and the support (steel on steel or whatever the two materials are) multiplied by the weight/gravity force on that saddle.

If both saddles are fixed for longitudinal movement then the thermal expansion of the vessel is restrained and the axial compression force in the vessel is distributed to the the saddles and then to the supporting structure as a load. Depending on the temperatures involved, materials of construction (i.e. SS expands ~50% more than CS), etc. these forces can be large.

BR,

Patrick

 

[AlbertStructural]

Thank you very much ThaiDavid and dig1.

In our case we have provided some room for movement via slots in bolted connection of saddle and the supporting structure so YES there is allowance of movement in ONE plane (longer side of vessel). And the sliding forces (frictional forces in analysis and design) are considered using "MU" value of steel with steel and then multiplying the same with weight of vessel.
I was wondering how significant are the thermal forces in smaller direction (perpendicular to the longer direction which is having space for movement) ?

Regards.

 

[dig1]

Albert,

Normally I have not see these to be significant. You would need to see how large the movement is and the vessel designer may need to take this in account.

Patrick