I'm modelling a slug flow condition using spectrum analysis. In the field the pipe goes up and down due to vibration in some places and hit the structural supports. This condition finally produces oil leakage at the junction pipe-support. I´m trying to avoid this using clamps in order to control the vibration. The problem is to calculate the vertical force(up) that I need to control.
When i use SRSS or ABS combination I get a force at the support without sign (+ or -). I understand this force is going down (-Y), but What about force going up? (like in the field trying to lift the pipe?)This force can't be the same magnitude of the force going down because the weight is acting always in the -y direction.
Can anyone help me with this problem?

Regards,
Edgar Rincon

Edgar,

Are you sure that this is "slug flow"? To me it seems more like an abrupt process condition with intermittent flow conditions (I mean a pulsating type of flow)!!Though I can't be 100% sure about it as you've not mentioned whether your line is horizontal or vertical at the points of vibration. Can you elaborate your problem a bit more like the layout,supporting,process parameters & line size.

In the meanwhile, get information from the site such as the displacements (amplitude) of vibration, nature of vibration (like incessant or occuring at longer intervals) etc!!

As you've correctly said , the forces in negative & positive directions won't be equal in magnitude.
But in order to get to the crux of the problem, elaborate your problem.

SJ,
According to the process department the flow pattern is intermitent (slug). The pipe is 24 OD Sch std. Liquid density: 59,2 lb/ft3, mixture velocity 34,66 ft/sec.
You can see 3 pics with the configuration

Edgar,

The data is still vague to reach to any conclusion. As you've quoted, slug is intermittent & therefore, shouldn't cause cracks at the locations suggested in the snapshots!!!

Moreover, these are the locations with no fittings attached except the supports. The cause of the leakage could be the high reaction forces in the pipe at the support locations causing the support to penetrate or develop crack in the pipe.

Try to get the vibrations data from the site & carry out local load analysis at these points (you may use FE pipe etc) & if required, strengthen the pipe at these locations if Support penetration is the root cause.

Also, carry out a validation of the supports at the site (whether they conform with the supports given in analysis). Sometimes the things at site are different than what is expected through design!!

I hope you've ensured that your analysis is correct!!!

Dear Edgar Rincon,

With reference to your information, the problem may be due to large displacements. Try to provide axial restraints as many as possible near to the large displacement locations.

My query may be silly but still i need to mention it. Is your piping system is provided with Reinforce Pad (RF pad), since you mentioned that the leakage is at the contact between the pipe and support.