Dear all,
my question is:

When using Cold Load Spring Hanger Design the load variation in the hanger report is calculated by dividing the |(travel)x(spring rate)| by the cold load instead of the hot load.

Can anyone comment on this?

Can you tell me if this is supported in any standard or recommended practice?

Thanks in advance,

Eduardo

The CAESAR II hanger selection process collects two values to select your spring - a load and a travel. The stiffness of the spring "candidate" is used with these two values to test min/max loads and load variation.
At this point there is no distinction made on the load used - cold or hot, or, better, installed or operating. It's the (default) hot load or the user-specified cold load.
MSS SP-69 defines a "variability factor" = (travel*k)/Operating Load.
I would call our term "load variation" = (travel*k)/Hgr Design Load.
They may not be the same.

Hello Mr. dave

Thanks for the reply.I have the same query. Can you please elaborate your answer in view of question asked by Mr. Eduardo.
I also want to ask when cold load spring design is used.

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Regarding hot setting and the details you can see this- "Piping design and Engineering", by ITTGrinnell.

The denominator in % variation calc (while doing manually) depends on hot/cold setting.

In simple terms to differentiate.
Let us assume a Rest/+Y support has been placed in place of hanger and the SUS load is W1.

Hot setting/Selection is done in such a way that Hanger carries W1 load at Operating, ex: W+D1+T1+P1, i.e, It is designed to take Dead weight at Hot condition.

Cold setting/Selection is done in such a way that Hanger carries W1 load at SUS ex: W+P1, i.e, It is designed to take Dead weight at Cold condition.
In this type of setting, System floats/balanced at hanger location in Cold condition.

You can do a simple homework for a CAESAR II file with hanger close to nozzle, you will find that Hot setting in most cases yields a lower load at Nozzle in OPE cases.