Hello,

I got a few questions about slug loads.

I have read that "Slug force need not to be applied at the elbow in the vertical down comer".
Why?
because of the gravity?
and what if the elbow in the vertical down corner is at an angle?(from XY direction to Z direction)

Best regards,
Rick

Its need to be applied. Slug flow is intermittent two phase flow, where in the there is mixture of heavy settled slug and liquid/gas.
there are other types of two phase flow annular/dispersed etc but slug flow analysis is not required in these cases.

In slug flow the slug is forced by gas/liquid hence create an impact, its applicable in horizontal and vertical case both.

Hope this clarifies your query.

If there is a rigid vertical support anywhere along that vertical run, the vertical component of slug's change in momentum will load the restraint rather than cause the piping to move off its centerline and produce a bending stress. In this sense, there is little reason for a CAESAR II evaluation of that vertical component.
While the vertical component of this slug load causes no bending stress, I would ensure that the pipe/support assembly can withstand two times the calculated change in momentum load (i.e., DLF=2).
The load requires consideration, it may not require analysis.