Gaskets for Flanges for low pressure steam--what type/material?

JUGHNE

Have to reconnect to existing flanges for steam job, the surfaces are less than perfect.

They were not leaking with 5 PSI on them from the old system.

I will be under 2 PSI on new system.

The flanges are cast iron, 4" pipe, 9" flange diameter, 8 X 5/8" bolts.

I was thinking of some standard 8 bolt hole gasket supplemented by hi-temp RTV to fill the imperfections on the flanges.

Supplier sent me "Flexitallic CG1L 150, these are drop in gaskets with no bolt holes.

Any thoughts on how these will seal versus the old school type with RTV.

Flexitallic states to not use any added sealant.

Intplm.

When the face of which the gaskets are to be applied and is a little damaged, the Flexitallic type gaskets are not always forgiving, ie. they don't always cover the imperfections of the face.
A high temp rubber gasket rated for steam and a full face, and not a drop-in are a good choice. Rtv added is fine to find and cover any imperfections on the metal face.

EBEBRATT-Ed

Flexatallic are usually used on high pressure steam. I would use just regular Garlock gaskets. Get the 1/8" thick ones not the 1/16". RTV can't hurt.

Technically, cast iron flanges(smooth face) are supposed to have full face gaskets and steel flanges can use ring gaskets but on low pressure this rule is violated all the time with no issues. I usually Never Seize the gaskets and the bolts

I would't use any rubber gaskets on steam. I have never seen one rated for steam

mattmia2

Synthetic rubber to some extent relies on flexing with expansion and contraction to seal and most formulas harden over time so they may cause a leak after a couple decades where a fiber composition gasket might not.

ethicalpaul

EPDM seems to be good to 120C or even 150C with special formulations.

dopey27177

Garlock gaskets for lp steam. Never ordered pre-made gaskets. Always made them on the job. My helper would clean the flanges while I made the gaskets. Only bought 4x4 sheets of garlock some 1/4" mostly 1/8" thick.

I guess for a big job like all the gaskets in the school I would buy pre-made gaskets.

Cleaning the face of the flanges, I used a Stanley Putty knife, Cut down to 2 1/2". sharpened the blade like a plane blade.

A wood chisel 1" was used for the real heavy stuff and the final cleaning the putty knife.

After cleaning the flanges where needed I used J&B epoxy to fill holes in the flanges and before the epoxy got hard I used a wet sponge to smooth out.

Using flexitalic gaskets one must be careful because in most cases they can be used only once. Looking at the flexitalic gasket you will see a raised portion of what looks like many rings around the gasket.
These rings collapse when tightening up the flange and as such make the leak proof seal.
When tightening the flange bolts you need to do that similar to tightening a wheel on a car. This will assure that the rings will compress evenly.

In my view flexitalic gaskets should only be used on high pressure steam 100lbs and above.

Jake

ChrisJ

I've never done it before, and I do not work with commercial steam, but what about cork sheets?

I've always had good luck making cork gaskets and they seem to last an awful long time. I can't imagine why they wouldn't work with low pressure steam.

JUGHNE

Thanks for all the input on this, learned a lot from all of you on this.
I have to deal with only 2 sets of existing 4" flanges and have positioned them such that they can come apart by maneuvering several 3" unions.
Hoping to never have to open them again.

Have some full faced 1/8" gaskets (not red rubber) for steam on their way to me.