A word of caution: you mention 7-8 feet, for combustible vapors, it should be
minimum 10-ft
See API-521 section 5.3.2
Where the atmospheric vent handles combustible vapors,
the outlet from the vent should be elevated approximately 10
feet (3 meters) above any adjacent equipment, building,
chimney, or other structure. Provisions should be made for
drainage of each vent pipe so that liquid cannot accumulate in
the vent.
Paul Bowers <pbowers@pipingdesign.com> wrote: Nozzle/twister writes at <a href="http://www.eng-tips.com/viewthread.cfm?qid=156173&page=6:">http://www.eng-tips.com/viewthread.cfm?qid=156173&page=6:</a>
<<What I've been taught is that the bevel is to deflect the release and noise away from the structure or operating area. In the old days it was common to see short tail pipes at the edge of a structure at mid-level. Now most vent pipes exit at a minimum of 7 or 8 feet above the highest nearby access level.
The bevel does create a horizontal component (on a vertical pipe) that serves to increase the bending moment on the tail pipe dramatically, increasing stresses and complicating the support/guide scheme. There is a good discussion of this in ASME B31.1, Appendix II.
The bevel does not increase the capacity and has outlived its usefulness. A bird nest is not going to slow down a release, though the bird may get the ride of his life.
As a Pipe Stress Engineer who is responsible for supporting and restraining these vent pipes, I always request the ends to be square cut at 90 degrees unless the client has dictated otherwise.>>
See the URL above for more discussion on the subject.
Paul
[Non-text portions of this message have been removed] Received on Sat Feb 10 12:20:00 2007
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