Rupture Disk Reaction Forces For Closed System

I tis not possible to consider steady-state flow through a rupture disk, as by definition, before the disk bursts, the flow is zero, and after it has burst the flow spikes and then drops exponentially to protect the upstream vessel against overpressure.

My question is not to consider steady state flow through ruptue disc,but after first elbow downstream of RD ,will it be a steady state flow?The first elbow can be checked for Impact/shock loading as per API RP 520 Reaction force calculation,there is no clear guide lines in API RP 520 Part -II or ASME 31.1 regarding rupture disc.Do we need to consider the forces on each elbow in caesar modelling upto the header connection?if so what is the basis?If process confirms the flow type as steady state can we only check the piping for impact/shock loading at first elbow downstream of RD?

As a precaution: Our experiences with rupture disks show that they have very little tolerance for fatigue loads. You may find that pressure cycles on the disks will lower the rupture pressure of the disks. The vendor should be queried in regards to their product, if your pressure will be cycling on the disk.

dear BDThompson,

My Query is regarding stress analysis of the piping system involving consideration of reaction forces to be considered in software -CAESAR-II,API RP 520 & ASME 31.1 gives the formula for calculation of these reaction forces.

Usually PSV for closed system is checked for Impact reaction force & bending moment generated due to the forces ,forces considered only at first elbow downstream of PSV for steady state flow since the forces will get balance for rest of the elbow pairs,

But there is no clear gudelines I could get in applicable code for both PSV & RD?looking for basis to ignore these forces consideration except @ first elbow,flow type is confirmed as steady state flow @ downstream of PSV & RD.Could any one help me find the basis for this?