Comparing Allowable Force and Moments at terminal points in Caesar II
While doing Piping Flexibility analysis in Caesar II, whether we need to compare the forces and moments at terminal point with allowable?
If the terminal point is pump nozzle or vessel nozzle, the forces and moments from the piping can be compared with the allowable from the vendor. The forces and moments exerted from piping on pump/vessel nozzle should be less than allowable from vessel manufacturer. What we do if the terminal point is in pipe joints(our scope is before the weld joint and the customer's is from the weld joint). How to compare?
Kindly explain.
Thanks in advance.
Regards,
K.Parthy
Re: Comparing Allowable Force and Moments at terminal points in Caesar II
..from my experience..for instance for packages..one if the solutions is:
To create a real anchor point (rigid pont) at the point where your scope of work or delivery ends up..
so you your model ends up with an anchor..and the remaining part, which is not in your scope ends up with the same ancor
these anchor are also handy for shipping and hoisting the package(s)
Another solution is take/include in your stress model ..an overlap (which means include in addition to your own piping, a part othe piping with its supports, of the matching piping which is just outside your scope/boundaries, for guidance: include 5 to 6 rests and 2 guides + one axial stop )
Re: Comparing Allowable Force and Moments at terminal points in Caesar II
Thanks FATHI.
Normally we use the first method of creating a real anchor point (rigid pont) at the point where our scope of work or delivery ends up..
In one project we got the stress analysis report from customer for their scope of work. We had a common anchor point as you said.
From Restrain summary report, the forces and moments from our analysis at anchor point is Fx=-146Kg, Fy= -148Kg, Fz=107Kg, Mx=-164.8kgm, My=688.8kgm & Mz=17.8kgm but from the customer report we find their values(Fx=-2.1Kg, Fy= -3.799Kg, Fz=-300.9Kg, Mx=-60.5kgm, My=322.04kgm & Mz=8.2kgm) are less than ours. Their value is less because their routing is in such a way of reducing the forces. The pipe size is Dia.219x6.
But Code stress passes for both.
Then i tried by entering the forces from the customer report as input in my analysis, but found that the forces have been summed and the report is Fx=-148Kg, Fy= -145Kg, Fz=-194Kg, Mx=-255.4kgm, My=1010.9kgm & Mz=26.1kgm.
How to solve these kind of issue.
Re: Comparing Allowable Force and Moments at terminal points in Caesar II
..I suggest to segregate/ differentiate between the loads>
thermal apart.
weight apart
etc..
that way you will see better ..and can make a sound judgment
Re: Comparing Allowable Force and Moments at terminal points in Caesar II
Re: Comparing Allowable Force and Moments at terminal points in Caesar II
.I mean..in other words differentiate between Thermal , Wieight and pressure
I you have this in the piping Codes
And you have it also in ASME VIII div. 2 when one distinguish between primary , secondary and peak stresse..
combining the loads (use operating load) means almost nothing
Primary, secondary, peak and occasional have EACH ITS OWN ALLOWABLE LOAD OR STRESS
Re: Comparing Allowable Force and Moments at terminal points in Caesar II
.I mean..in other words differentiate between Thermal , Wieight and pressure
I you have this in the piping Codes
And you have it also in ASME VIII div. 2 when one distinguish between primary , secondary and peak stresse..
combining the loads (use operating load) means almost nothing
Primary, secondary, peak and occasional have EACH ITS OWN ALLOWABLE LOAD OR STRESS