Boiler Flange, Gasket or sealant?

I have an oil-fired boiler for heating my home. This one is welded steel. There is a large flange (about 9" in diameter & secured by 6 bolts) where the controls & immersion coil go into the water jacket. It is currently sealed by the original gasket which is now leaking a bit. I bought the standard red 1/4" thick gasket matetial with plans to cut out a new one & replace it, but I have to wonder if there isn't a better, cheaper way.
Can I simply seal this flange with high-temperature RTV (also known as Silicone Rubber). The Black stuff is rated for about 600 degrees. Any thoughts?
Mike N.
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Do you want it cheap?? or do you want it right??

Yup, quit while your ahead, call a *competent* tech that has the correct gasket out of the proper material, and the correct sealer. Have you thought about what you gonna do if your repair leaves you worse off than when you started?? wrong gasket?? worse leaks?? broken bolts?? cracked flange?? flange corroded beyond acceptable limits?? FWIW, RTV is not a good thing on *ANY* steam system.
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posted for all of us...

Call the nice person that services your boiler (if you get it serviced). This job can be a real pain in the rear to fix and do it now while they are not backed up stem to stern with service calls and it's not real cold and snowy and messed up. It might be painful to pry a few bucks from your purse but think of the satisfaction you will have when you watch the poor person struggle with it to fix it and you can put wooly socks on your feet propped on the barfolounger with your loved ones surrounding you with warm tidings of the holiday season and winter instead of flames and hot spit emanating from both your spouse and boiler in equal amounts because you patched it with rubber cement.
--
Tekkie Don\'t bother to thank me, I do this as a public service.

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Gents,
How about some information rather than just lecture..... Is there something wrong with High-Temp RTV? If so, what it is it that is wrong? It works in automotive applications at higher temperatures and similar pressure.
For what it's worth; I have a supply of the "correct" gasket material. I also see that the same material installed about 10 years ago in other small flanges on my system, is now rock hard. So, I suspect the classic material is not ideal either.
Mike
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Pardon me Mr Tightwad, but as I said before RTV is *NOT* designed for nor is it intended for use on a boiler. Try this http://www.lawsonproducts.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId 001&storeId001&productIdS822&catpath=All+Products%2F%2F%2F%2FUserSearch%3DANTISEIZE The gasket material itself is not supposed to last forever either.
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Noon-Air,
I don't particularly care for your derogatory tone or the childish name calling.
In addition, you appear to be not-very-well-infomed as in the mean time I found a reference in a Carrier Manual on servicing their cast boiler. Carrier instructs.... "Reseal seams between adjacent sections as necessary with 400F RTV"
Mike
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Noon-Air,
One more thing... You had best get in touch with Weil-Mclain also & let them know that "RTV is *NOT* designed for nor is it intended for use on a boiler."
It seems they are unaware of this fact. Damn those stupid manufacturers....They call for & recommend it to seal boiler sections too. In this case they cal for "RTV silicone sealant (Dow Corning 700 or 732 )"
Mike
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No. There's nothing long and painful about replacing a gasket. Use a Flexitallic if applicable.

No one will stop you. Why don't you just do it then? You came here asking, didn't like what you heard, and are now "telling" how it could be done? Nice...
It may not leak right away. Does that mean it's fixed? It is not the correct or acceptable way to repair your leak, nor is it safe. Considering "how" it will fail as a blow-out instead of a small leak as gaskets are anticipated to do, should they fail.
If you called a repair company out, and this is how they "fixed" your boiler, you would be told how you got screwed, and the tech should be fired. End of story, do it right. Don't take this the wrong way, but you do not appear to be qualified for tackling this particular repair properly.
-zero

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Actually I got to the bottom of the issue by digging into the manufacturer's info available (but pretty buried) on the web.
1.) RTV is the recommended material to re-seal boiler sections. Manufacturers recommend it in locations where the seal is not at a serviceable location. RTV has longer life & less degradation with temperature than the gasket material (which is Buna S). But it has disadvantages too.....
2.) There is a cure time, so the boiler can't be promptly fired up. In addition, it not easy to take apart later. So it is not ideal for a seal which has to be broken for service in the future.
In my case, the flange mounts an immersion coil. The coil is meant to be serviceable, so naturally they use a gasket to allow disassembly.
I don't use the coil any longer, I'm actually going to discard it & plug the ports.
With the coil discarded, this flange never needs to come off again. So, I think I'll use the sealant that manufacturers recommend on their non-serviceable joints (like boiler sections).
Mike
p.s. Thanks for your gracious & professional exchange of information
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On Fri, 28 Dec 2007 06:34:33 -0800 (PST), ml snipped-for-privacy@yahoo.com wrote:

Like most of us in here really thought you were even going to listen................haaaaaaaa. Oh, by the way, in a boiler.........never say "Never". Its only a matter of "when". Are you an EE? Bubba
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In addition to everything everybody else said, be prepared to have to drill out and replace at least one of those bolts that will probably break when you try to unscrew them to remove the domestic water coil. That's why nooner referred you to the anti seize product you should use on the new bolts when you put them in.
This not a fun job and if you are going to do it yourself, this is not the best time of the year to have your boiler disassembled and unable to put back together in a timely manner.
On the other hand if you enjoy complete frustration, this will be an enjoyable job. Piece o' cake.
Make sure you are likkered up when you do this, as it helps you laugh at yourself.
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