Wheep hole on RF pad
Wheep hole on RF pad
(OP)
Dear experts,
Is there any article or code that we can refer to about the requirement of wheep hole or vent hole on RF pad on the shell plate ?
RF pad for nozzles and manhole always with vent hole. But RF pad for pipe supports or other attachments could be there is or there is not.
What would be the serious impact if there is no vent hole on RF pad of pipe supports or other attachments ?
Some of my welding supervisors explain me the welding method for the RP pad without vent hole to minimize gas trap.
Any comments ?
Is there any article or code that we can refer to about the requirement of wheep hole or vent hole on RF pad on the shell plate ?
RF pad for nozzles and manhole always with vent hole. But RF pad for pipe supports or other attachments could be there is or there is not.
What would be the serious impact if there is no vent hole on RF pad of pipe supports or other attachments ?
Some of my welding supervisors explain me the welding method for the RP pad without vent hole to minimize gas trap.
Any comments ?





RE: Wheep hole on RF pad
Of course, it allows you to leak-test the fitting welds, and allows you to detect leaks on the interior welds.
And it allows venting of that space.
Uniform pressure inside a cylinder tends to keep it round. If you have a reinforcing pad sealed to the shell, with the space between it and the shell somehow vented to the inside, rather than the outside, that little section of shell plate will have zero net pressure acting on it, and would tend to form into a flat spot, transferring the load to the repad instead of the shell. I've never seen this effect discussed anywhere, never heard it given as a reason for that vent, but it seems to me that it does serve a structural purpose as well.
RE: Wheep hole on RF pad
Are you perhaps lonely or just enjoy the company of a merry tune ???
https://answers.yahoo.com/question/index?qid=20130...
MJCronin
Sr. Process Engineer
RE: Wheep hole on RF pad
RE: Wheep hole on RF pad
I am sorry for misspelling.
But the question still the same. What would be happen if there is no vent hole on the RF pad of pipe supports ?
Is there any significant effect ?
Syah
RE: Wheep hole on RF pad
A significant issue behind having a weep hole, as note above, is that the re-pad attachment to the pipe is not designed or tested to be pressure containing. If you get any corrosion hole or other hole developing in the main pipe, you want this to be noticed before the re-pad becomes the pressure containing element, hence the other names - vent hole (gas) or weep hole (liquid) or tell-tale ( either).
The issue over gas blow into the weld is also significant, but the pressure containing bit is the most critical for me.
Welding RF pads for supports sounds a bit old fashioned to me if these are just used for direct contact onto a rubbing bar or similar. Clamp type supports are now much more common in my experience.
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RE: Wheep hole on RF pad
RE: Wheep hole on RF pad
Reading API 650 a bit closer shows that the only requirement for non opening attachment requiring a tell tale hole are when you run over a seam weld.
However I still think it's a good idea regardless - 5.8.11.4 applies here. Note requirement for rounded corners.
Makes more sense now why this is in the storage tank forum....
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Wheep hole on RF pad
For API 650 new tanks, the only requirement for a tell tale hole are when you run over a seam weld. Otherwise it's a non-issue.