Prevent rainwater in vent pipes
Prevent rainwater in vent pipes
(OP)
I have a small problem in my plant with vent lines. The current design has the tip of the pipe slightly angled (45 deg) to prevent rain water entering the main system. But this is not sufficient and it is important for the system to remain dry. I am tempted to increase the angle to a full 90deg or place a shroud over it but I am concern about dispersion issues. Has anyone dealt with this before??
Point to note, these vent lines are used occasionally, say once every two months.
Point to note, these vent lines are used occasionally, say once every two months.





RE: Prevent rainwater in vent pipes
RE: Prevent rainwater in vent pipes
I recommend That you leave the vent pipe pointed straight up. The end of the pipe may be straight cut or 45 deg angle cut, it makes no matter. At the bottom of the vent pipe, in the horizontal portion after the PSV drill a "weep" hole in the bottom of the line. In this way any rain water will drain out and not cause back-pressure problems.
If there is a concern about vapors purging out the "weep" hole during a major relief then connect a drain line to the "weep" hole and run it to a safe location.
RE: Prevent rainwater in vent pipes
RE: Prevent rainwater in vent pipes
A better answer seems to be the poly "socks" that people are putting over the pipes these days. It only takes a couple of oz dP to launch them and once they're gone they don't create any dispersion issues (like the hinged caps can). If you can't find the cap after a launch, they're not very expensive.
David
RE: Prevent rainwater in vent pipes
I would like to review the use of these ‘poly covers’. Does anyone the technical name for these??
Many thanks again.
RE: Prevent rainwater in vent pipes
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You can also review the conversation at this thread on this website:
thread292-168893: ASME VIII, I, UG-135 vs API 510
RE: Prevent rainwater in vent pipes
Why not just fit a 'gooseneck' on the end of the vent. This can be welded to the end or a clamp-on arrangement. A gooseneck is a 180 degree turn on the pipe vent end., so there is no ingress of rain. A fine metal screen, similar to a pot scourer can be incorporated to act as a spark arrestor. This is a common arrangement on fuel and chemical tanks.
Offshore Engineering&Design
RE: Prevent rainwater in vent pipes
Good luck,
Latexman
RE: Prevent rainwater in vent pipes
David
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
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RE: Prevent rainwater in vent pipes
A larger diameter end section of some length fits over the tip and is fixed and located concentrically with the vent by at least three space bars to leave an annular space between vent stack and new tip.
Any rainfall that is not exactly vertical will impinge on the inner wall of this end section, run down and then drip down the outer wall of the main vent stack.