B31.3 and iso 14692 together: OCC factor in load case disapp

I have a caesar model where part of system follows B31.3(metal pipes) and the other part of system follows ISO14692(GRP pipes).

If you have a iso14692 model only, in load case you will have OCC factors for SUS, HYD and OPE cases.
(see this image https://i.imgur.com/zykrpmk.jpg )

BUT...

when you add a pipe B31.3 the load case table will change and part of OCC factors disappears.
(see the image https://i.imgur.com/xOs0u55.jpg )

So the question is: OCC load factor are needed for GRP pipe to calculate che f2 factor. but if OCC factor in table disappear... how can caesar calculate f2 in right way?


How can i solve this problem?

The typical advice is to essentially double up the load cases and ignore stresses in sections of the model that do not apply to the pipe in question. If you organize your system well, you can use the filter options in the output editor to semi-automatically report accordingly.

The alternative would be to model all your cases with CNODE anchors at specification breaks, ignoring stresses altogether, and obtaining displacements, and applying those displacements to "b31.3 only" pipe and "ISO14692 only" pipe in separate models.

can you please explain to me how can i do it?

1)
if i double the load cases (how can i do it?), i always will have the "missing OCC factors"?

2)
how can i set the model to ignore stress for some part of model?
doing so, the OCC factor will appear again?

thank you

I can see how how our application of design factor and part factor for ISO 14692 piping can compete with the B31.3 "occasional load factor" (k, the 1.33 in the 1.33Sh limit for sustained plus occasional stress evaluation).
Rather than doubling up on the load cases, I suggest you consider running the model twice - once under B31.3 and a second time using
ISO 14692.
I cannot completely endorse this approach because I have not confirmed that the structural evaluation (pipe position and loads) is relatively consistent between the two codes.

I'll defer to Dave's expertise on this, but to answer your question, you can instruct the output editor to filter your results by node number.

I would also add to it that you can choose to alleviate the problem of computational paralysis through administrative adjudication. Place an anchor near the pipe interface and analyze them as two separate systems.

Although it does not allow the user to explicitly enter the occasional load factor, I have made some cross checks on the allowable stresses calculated by Caesar II for the parts under ISO 14692 and noticed that the correct value of the occasional load factor was automatically considered.

It would be nice if Dave or someone from coade can confirm this.

Thanks

As long as you have proven it thru manual checking, I think it's enough proof that Caesar is doing its job internally in its system. Actually, Caesar have done a good job in automating this ISO 14692 Compliance check. I remember one FPSO project I've involve with where our Senior Stress Engineers have set up a spreadsheet to do this ISO 14692 Compliance checking.

Now it's very convenient, but still it's nice to know how to do it manually, so you have enough confidence in interpreting the results in whatever software you are using.

Cheers!!

To ensure the correct factors are being used, you best first make all the required load cases and then add the steel parts/code to your model. In my experience it can get messy when load cases are added/altered after both ISO and steel codes are in the model. Haven't checked this with v12 though.