Hi,

What is the value that should be used in CAESAR II to calculate the reactions due to the thrust force in curves in a transient event?

T = PxA

or

Resultant = 2xPxAxsin(Angle/2)?

See Figure Attachment

Depends on the event.
If you are evaluating a pressure wave traveling through the system, the imbalance will be in each straight run of pipe. That run will have a higher pressure on one end than the other. The load would be delta P times the inside area of the pipe and it is directed along the run. Exceptions include reducers and similar where the area changes. Here it's your T=PxA.
If, however, you are looking at a change of momentum caused by a change in mass (a liquid slug in a vapor line), the vector sort of resolves in the direction of your (2PAsin...) but it has nothing to do with P. I would use something more like SQRT(2)*rho*V^2*A for that vector magnitude.

Depends on the event.
If you are evaluating a pressure wave traveling through the system, the imbalance will be in each straight run of pipe. That run will have a higher pressure on one end than the other. The load would be delta P times the inside area of the pipe and it is directed along the run. Exceptions include reducers and similar where the area changes. Here it's your T=PxA.
If, however, you are looking at a change of momentum caused by a change in mass (a liquid slug in a vapor line), the vector sort of resolves in the direction of your (2PAsin...) but it has nothing to do with P. I would use something more like SQRT(2)*rho*V^2*A for that vector magnitude.

Thank you Dave.

In my case I am evaluating a pressure wave traveling through the system, then T = PxA acting tangent to the curve.

But I have a question, is the intensity of this pressure wave independent of the angle of the curve? Will it have the same effect for a 15 degree curve or for a 90 degree curve?

Hi,
Any answers?

I'm afraid that mixing in your sentences "pressure wave traveling", "T = PxA", "acting tangent to the curve" and "intensity of pressure wave dependent on (or independent) on the angle of the curve" you succeeded to destroy all the good intention I would have. I think your first step would be to understand what Dave wrote.

Separate the resultant force into x, z direction(y is vertical)

Mariog ... what's your contribution to the question? be clear...

The question is, in a transient event, regardless of the angle of the curve, the intensity of the applied thrust force tangent to the curve is the same (for liquid). See Fig 13-13.

What Dave said is clear, I just need confirmation of the angle of the curve ..."If you are evaluating a pressure wave traveling through the system, the imbalance will be in each straight run of pipe. That run will have a higher pressure on one end than the other. The load would be delta P times the inside area of the pipe and it is directed along the run."

Thank you

Yes, what Dave said is clear, "the imbalance will be in each straight run of pipe" "the load would be delta P times the inside area of the pipe and it is directed along the run." I mean it's about delta P and not P, it's about straight runs of pipe, not other tangent to the curve, etc.
Obviously, a consequence of the angle of curve is the position of the adjacent straight run. And no, the theory does not consider any other "wave intensity" when travels through the system.
In case you are able to develop other theory, more elaborate, I'll be happy to see it.

My contribution to your original question would be to convince you that the effect of the same P*A on both "ends" of a straight run is a longitudinal stress commonly counted as PD/4t (or more accurate P*A/Am), i.e. one already considered in calculation. In case you consider a transient event, the figure you've attached is not helpful because there the pressure is considered with the same values at both ends of curve.

In case you are focused on transient events as slug, I think you may take a look to the article I attached in http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=60278, even it's possible to rise up questions instead to give certitudes.

Thanks mariog for your help!

I'll clarify my doubt.

See the figures below:

Note: The graph (trip pump) refers to the pressure peak at node 850.