Doesn't the order of the load cases matter, so the OPE+FORCE should be above the sustained case? Or does that not matter in your example because there's no expansion cases doing algebraic combination?
Thanks sjkji. But the skid edge loads are not Occasional load, I guess. Do you apply the skid edge allowable loads for maximum and minim design temperature too. Or only operating temperature.
What do you mean by "edge load"? Caesar II is looking at the piping so if you're talking about skid anchor bolts or something that is not really relevant.
If you have some defined force on the pipe at the edge of the skid, ensure there's a node at that location and apply external force/moment. You need to consider what is causing the force. If it's occasional due to equipment loads or something, then it is an OCC load. If it's something in the skid that is 100% always applying load and not dependent on temperature, I would consider adding it (F1) to the sustained case.
So both L1 and L2 in sjkji's example above would now contain F1 and L3-l5 would go away.
Hi RVAmeche, Thanks for your reply. I am given a Skid Edge Allowable Load Table by the EPC for different class of flanges to apply at the skid edge where the yard piping will get connected with package (skid) piping. These loads will be always there. In this case, should I consider these loads as occasional load? The load cases shown by Sjkji is for Occasional Load such as PSV force/slug force etc.
I think you're misunderstanding what you're being provided.
The EPC is giving you the ALLOWABLE loads on the flanged skid connections. What you need to do is analyze the piping at these connections and ensure the configuration is such that the allowable loads of these connections is not exceeded.
The EPC is not saying these are constant loads that are always present in the system; they are saying the forces applied to the skid cannot exceed those values. This is common for equipment connections where exceeding those forces could result in damaging the equipment.
In other words, there are no applied/external forces being put on the piping here; you need to make sure the piping is not putting forces greater than the given allowable loads at those connections.
Thanks RVAmeche for the nice explanation. I 100% agree with you and that was my initial understanding. However, EPC is saying that the yard piping is gonna give these load to the skid piping and the skid piping support has to be strong enough to take these loads.
The EPC is saying that the piping connections to his skid MUST be subjected to those loads all the time? What? Unless there's something odd about the skid that you haven't mentioned, that makes no sense.
If he's worried about your pipe support just outside the skid, you can apply the external force vector, with the same magnitude as the allowable loads provided, at those connections to make sure the support loads are still adequate. If so, the initial load case example provided still applies.
But seriously, ask him what he's talking about. The skid piping connection can handle x (loads given to you). The piping outside the skid being analyzed by you will result in y (loads determined by Caesar). As long as y < x and your supports can handle y, everything is fine.
