Modelling of large diameter valves

Hello everyone.
I have to modelling 48 inches ball valves in pig station. 48 inches ball valve weight is 24778 kg and running at X direction. Since the weight of valve is too big i have restrained the valve with +y supports, moment Rz and at X direction as limit X. Do you think these restraints are true?

What do you mean? What supports are actually near the valve?

Valve length is 1500 mm and from node 80 to node 85 is a ball valve. In real there is a concrete block support to carry weight of valve.

Valve length is 1500 mm and from node 80 to node 85 is a ball valve and rigid. In real there is only a concrete block support to carry weight of valve. But, to me since the valve weight is too much, valve can not move and rotate any direction. So i restrained valve with limit and Rz.

Ah I see. Personally I would rather model the simple +Y, with friction if applicable, to capture most of the valve weight (similar to actual condition) and see what the model does.

You're assuming the valve body does not move or rotate; I'd rather have the results confirm that's the case instead of assuming it. Just because it's heavy doesn't mean it doesn't move.

Mr. Richard, Mr. Dave could you please answer my questions?

Zall,

Nobody can answer that question without more exacting details on the support, except the person who can drive its design accordingly.

I will note that you have 2 +Y supports in close proximity to each other in this design. The only way the valve could rotate in the Z axis is if the line picks up off of one versus the other. Thus, it's likely that the RZ component is superfluous, regardless if it's actually true.

I will also note that if you have two limits without gaps between the two, you're going to end up with incredibly huge loads between the two. This is fine, unless you're using CAESAR to drive the design of the support. Simply having one limit should be sufficient for the task at hand.

Actually to i find for load on concrete support which arise from valve, i put two +y restraint. I thought that net force is average of two restraint load.

Again, I don't know what the support detail looks like, but let me ask a question:

If you stand on one scale, and I stand on another scale, how much load is placed onto the floor?

Your weight averaged with mine, or our combined weights?

I understand Mr. Fletcher. But i couldn't put only one +Y support In the center of the bottom of the valve. Then i put two supports.

Again, what is the actual support information.

Is the valve just resting on that concrete block in a saddle or something? Is it bolted/fixed to the support?

This drives how you model the support, not just the weight/size of the item.

The valve like in attachment and it has just resting on concrete block and there are a steel plate between concrete and valve foots. There is no bolt and not fixed.

Zall,

1 rigid element that's length L and mass W works the same way as 2 rigid elements that's length L/2 and mass W/2.

Common practice here would be to split the element in half and put the support in the center and place a +Y with friction.

Though, you could probably just get away with the 2 +Ys with friction, too.

If two, forces from both supports are to be added together for purposes of structural design.

Make no mistake - the valve can rotate in the Z axis. The criticality of whether it rotates on the first support or the second support is dependent on whether the distance between these 2 supports is anywhere in the scale of the rest of the pipe.

I wouldn't model RZ and X as you initially stated. You could model it like shown below, only +Y with friction at each support point.

The supports look flimsy to me. I wonder if it's actually meant for shipping only. You may want to do further checks to ensure that the supports can take the forces.

Agreed that those gussets look like they're for shipping. I'd definitely check the IOM or whatever documentation you have to ensure you're adequately supporting it.

Yes, looks supports for shipping only and I doubt they can take axial (thermal & frictional) loads from valve(self weight) plus piping. Better to ask valve supplier about it.

Well, this isn't the 48" valve that was referenced in the original post, otherwise I want to know what they're feeding the operators over there to operate a 48" valve with a handwheel.

But it is a valid point, nonetheless.

Michael, it's just a Manual Valve Actuator, worm gear type.

And the valve legs are common required under API 6D with the intention "provide a stable footing when the valve is set on a fixed base". It depends on the Manufacturer they are stiff or not as long they give this function.