Hello to all,

I was searching for postings concerning Nozzle Loads, but I am not satisfied with what I have found, and I got confused along the way, so I made a new post for my question.

EXAMPLE:
W: Weight of pipe filled with fluid.
T1: Maximum operating temp.
T2: Minimum design temp.
T3: Maximum design temp.
P1: Operating pressure.
P2: Design pressure.
E1: Seismic
W1: Wind


LOAD CASES

L1: W+T1+P1 (OPE)
L2: W+T2+P2 (OPE)
L3: W+T3+P2 (OPE)
L4: W+P1 (SUS)
L5: W+P2 (SUS)
L6: W+T1+P1+E1 (OPE)
L7: W+T1+P1+W1 (OPE)
L8: L6-L1 (OCC)
L9: L7-L1 (OCC)
L10: L8+L5 (OCC)
L11: L9+L5 (OCC)
L12: L2-L5 (EXP)
L13: L3-L5 (EXP)
L14: L12-L13 (EXP)

When checking nozzle loads, which load case do we consider?

Do we consider only L1 for the nozzle loads or do we take whichever is greater between L2 and L3?

Do we also have to consider L6 and L7 for the nozzle loads?



Thank you,
PIZZAPIPE

Q: When checking nozzle loads, which load case do we consider?

A: Follow the rules of your governing Codes.

Q: Do we consider only L1 for the nozzle loads or do we take whichever is greater between L2 and L3?

A: Refer to your design codes.

Q: Do we also have to consider L6 and L7 for the nozzle loads?

A: Refer to your design codes.

I'm sorry if this will require you to do actual work to collect your paycheck. Sometimes, it's unavoidable.

Well, I cannot argue with that Mr. CraigB.

You have been so kind, thank you very much.

Have your work checked by ur supervisor. I fear you are missing nozzle displacements. Your load cases also need a review!Question of nozzle loads come second to all above.

Hello Skyofstars,

Let's skip the nozzle displacement part, or the nozzle softness etc. I am already well aware of that.

My point is, there has been many discussions about this topic but no one seem to specify what they mean by T1 or P1, in a load case W+T1+P1.

Does T1 mean maximum operating temperature or is it the greater between maximum and minimum design temperature.

I am working with two fo my senior Pipe Stress Engineers here, but they have different ideas. One is considering T1 as maximum operating temp in his load cases for checking the nozzle loads, and the other guy is using the greater between the maximum and minimum design temperatures.

Thank you very much for your comments.


Best regards,

Pizzapipe,

Assuming you have +ve and -ve temperatures, the nozzle will be subjected to forces and moments due to thermal expansion OR contraction from the INSTALLATION temperature to maximum or minimum possible (design) temperature. It doesn't matter what you call it, T1, T2 etc.

The nozzle cannot see a coincident -ve to +ve temperature load. That is used to establish the STRESS RANGE.

Hello MoverZ,

So are you saying that we consider only the maximum operating temperature for nozzle loads in our load cases? and that the purpose of the max and min temp are only for the overall stress range, and that it has nothing to do with nozzles?

Thank you,

You can consider whatever you want to in your load cases.

Thermal nozzle loads caused by piping are primarily due to the change from installation temperature to whatever temperature exists in the piping. That may or may not be max or min operating, since there may be upset, excursions, regeneration, steam-out or other conditions to consider.

Stress range may have nothing to do with nozzle loads, particularly in a system with both high and low temps. In a system with a single temperature path (say from installation to hot), the same calc may be used for stress range and nozzle loads. However, you can use the hot modulus for loads, but not for stress range.

Dear PIZZAPIPE,

It's generally to include occasional load in checking nozzle load. For your load case using L1 to L7. Look at your client specification if they provided the nozzle allowable for such size and rating. If it is provided you can add one more load case for simply in checking Lxx = L1+L3+L4+L5+L6+L7) using max operation in load case combination TAB. If this pass no need to check one by one L1 to L7.

But new version of Caesar already provide the max without setting up load case Lxx I mentioned above if your nozzle node is in restraint (let say ANCH) or displacement boundary condition.

But don't ever use combination load cases in checking load. Only native load cases give the real result for force and moment like L1 to L7.