Modeling tank API 650

What is your opinion about modeling tank API 650 (rigid with displacement) including displacements as radial deflection due to fluid and temp as longitudinal rotational due to fluid and temp (these data from warnings output after modeling nozzle API 650).

Thanks

Nozzle with cnode which have the displacements (translations and rotations calculated by Caesar or by hand) + settlement is the proper way to model the tank because consider also the tank bulging.
The rigid without weight is not appropiate because it will reflect only the thermal expansion.

Regards,

I am facing the same problem with question of Hcamacho...so let me ask continued question..

If the nozzle is installed on the upper (but lower the top of shell height), Do we need to consider about tank bulging ?


If in case we need to consider about tank bulging, the method as below is correct or not for modelling support on the vertical pipe which attach to tank's shell?

1. At the nozzle : Model nozzle with cnode which only have displacement (translation and rotations)
2. At the bottom of tank : Model as rigid without weight which have only the settlement.
3. At support location : Model as rigid without weight with cnode to tank's shell

If not correct please suggest....


Thanks.

You can check and see that for a nozzle that is in the upper part the bulging and radial deflection due to fluid is small because the fluid column above nozzle is small.

But if you want to model your way, if nozzle displacements are D1 add also the settlement at nozzle on the same displacement set as for the tank (e.g. D9).

Regards,

Dear Dan,

pls enlighten me on tank modeling…

if tank is having Variable settlement say for eg 9” at the centre and 4” at the corner end in such case which settlement value shud I need to consider(9" or 4"?)

Case1: I not modeling tank ( pipe modeling upto nozzle+ CN Anchor + Settlement-upword thermal growth)

Case2: I’m modeling Tank (pipe modeling upto nozzle+ tank as rigid of tank size and thk +CN anchor + settlement) as shown below

4" for settlement.

Use case 1. Add also radial deflection due to fluid and temperature.

Thanks Danb for Earlier reply...
now I have one more doubt regarding rigid modeling for Tank

I have a Tank of SIZE 33 meters dia X 9 meter in height

Pipeline connected to tank nozzle of 56" size at height of 2 meter from bottom.

If I model rigid element with Tank dia 33m (1300") then I get heavy downword longitudinal Force (42tonnes) as compared to modeling rigid Tank with pipeline size of 56" loads are (18 tonnes).

and If Same system without modeling tank (rigid elements) with only using radial displacements and settlement

I get lower downword longitudinal force (4 tonnes) but huge moments

could you pls enligten

I'll correct my statement

"and If Same system without modeling tank (rigid elements) with only using radial displacements and settlement

I get lower downword longitudinal force (4 tonnes) but huge moments"

I get less logitudinal force but increment in logitudinal moment.

any experts from forum, kindly clear.