I have two questions:
1. In the "Valve Flange database", what is "FLG.PR"?
2. How is a flanged relief valve modeled?

Thank you.

1) FLG.PR is a pair of flanges.
2) Build your flanged relief valve as a bunch if appropriate rigid and pipe elements. There is no assembly for you to select from a database.

Thanks Dave,
So, do you build valve from elements and make them "rigid" individually (say a piece of pipe and a flange) or together?

If together, do you use the range of nodes to cover the parts and then make the "assembly" a rigid part?

Individual pipe elements can be pipes or rigids. I rigid element has a stiffness based on the entered OD & wall thickness using the calculated ID and 10 times wall. You can also specify the weight of these rigid elements.

So, it's a collection of pipes & rigids.

If you do not expect any relative distortion of this assembly, I'd run it as a single rigid element; of maybe two if you want to go up first, then over.