Davis:
Thanks, I am stuck with this one. The manufacturer machined the top of the
cylinder totally flat - just too much trouble to make a raised face I guess.
And could they even make a ring joint???Noo.
But, right on with the smooth faces. The cylinder and flange are reasonable rough, but the orifices are near polished finish, definitely not a threading cut. But what really gets me is the gasket - essentially cut Garlock material. And once it starts to leak, the gas is going to be cutting a channel. I'd like to see a manufactured type of gasket, possibly with some type of reinforcement wrapped around the ID to get the maximum crush, sort of like an automotive head gasket. Trouble is, these units are wanted on line, and everything good takes time...
We had done the lube and so forth - problem being, after a couple of times of tightening, we were skating on the plastic region on the bolting. DON'T want to go there...
George McK
George, you're going down the right track, seems to me. You need more load on the gasket and reducing the surface area under compression is the easiest and quickest way. Also...I've seen lot's of flat faced flanges that are machined pretty smooth. A sheet gasket will need some kind of finish to "bite" into. Smooth surfaces are extremely difficult, especially at that pressure. Best range is 125-500 RMS or AARH. Graphite would be your best bet for smooth flange faces and the thinner the better (1/32" or 1/16" tops if you flanges are "parallel"). Don't forget to lubricate the bolts and nut bearing surfaces so as to get even more load (less torque to friction, more for clamping).
Good Luck...........ohmmmmm
Hail, O mighty guru! A lowly and insignificant worm seeks erudition: I am troubled with gaskets.
We have an installation where a gas compressor cylinder has a flat faced flange, approx. 18 inch bore. Then, we have a pulsation reduction orifice and flat faced inlet flange. This whole business operates at up to 900 Psig, and up to 150 degree F temp. It was assembled with standard fiber type gaskets, no reinforcements or sealing rings. Amazingly, it leaks in spite of torquing to upper limit of the bolting. My take is that we are spreading the clamping force over the whole gasket area, while we are actually only sealing with the area from the bore out to the bolt circle. I am suggesting going to a Flexitallic type gasket, which would put the clamping load within the bolt circle. But, delivery on these is LONG! Alternate is to machine the thickness of the orifices (1/2" thick) outside the bolt circle, to put all the clamping force on the inner area, and go back to gasket material, but possibly with a sealing ring in! the ID. At least we could get this done quickly. Any alternate suggestions?
Thanks
George McKinney
----- Original Message -----
From: DAVIS MCCONNICO
To: PipingDesign@yahoogroups.com
Sent: Friday, January 23, 2004 1:56 PM
Subject: Re: [PipingDesign] What is Parallel?
Ha Ha Paul. But of course, the question was regarding flanges, not
gaskets. Hey, come to the mountain-top and ask me a gasket question, anything.
I'll answer as soon as I'm done meditating....ohmmmm.
Shouldn't someone with a screen name of "gasket_guru" know this already?
Just a cheap joke,
Paul
> From: gasket_guru
> When preparing to bolt up a gasket between two flanges, if a
> pipefitter were to say the flanges were "out of parallel", what
> exactly would he mean by this?
>
> Would he mean:
>
> A. Each flange face is flat, but relative to the mating flange, the
> sealing surfaces are not pareallel to EACH OTHER, or
>
> B. The sealing surface of each flange itself is not flat, but "wavy"
> or "warped", or
>
> C. Something comletely different.
>
> Finally...are there any ASME spec's regarding allowances or
> tolerances for A. or B.
>
> Regards,
>
> Davis
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[Non-text portions of this message have been removed] Received on Fri Jan 23 15:38:00 2004
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