Meta to metal face seal

[asimpson]

I have been tasked to make a metal to metal static face seal for steel cycling between 20 and 900C to contain steam at maximum 5 bar.

No gaskets or extra sealing materials. Good contact between sealing faces for thermal conduction. About 100-150mm sqr. similar to flange or manifold and bolted together.

What sort of flatness would be required for a for a steam-tight seal?

I might be able to use soft metal gasket but it would have to make good thermal contact.

Any thoughts welcome?

Many thanks

 

[SnTMan]

Like copper?

 

[dvd]

Sounds difficult.

A picture would be helpful.

 

[IRstuff]

Indium is one soft metal used as gasket material for high vacuum applications.

TTFN
faq731-376

 

[KENAT]

I seem to remember when we were playing around with new ejector cartridges in a test rig that copper seals were used.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[btrueblood]

Indium will not stay put at 900C. You'll want copper, or even gold if you could afford it. Copper will tend to bond to steel at those temp's., gold not so much, and gold will survive more temp. cycles before it fatigues.

 

[IRstuff]

oops, soory, my bad, I misread a table.

TTFN
faq731-376

 

[dumpsta]

you can try loctite 504. I've used it for sealing water piping flanges. Its made for low pressure seals. It was checked for leaks at 125 psi without any problems. Not sure about conductivity. I'm sure there are several types of loctite formulas that might fit your application

 

[btrueblood]

I don't think any loctite (or any polymer for that matter) will stay in place a 900C either.

 

[dumpsta]

whoops, didn't see that you don't want sealing materials

 

[Cockroach]

You need about 0.002 inch maximum over the contact surface' length and width. Surface finish is no less than 16 Ra. I suggest flashing an electroless nickel coat of 0.00050 inch depth.

Good luck with it. Standard valve problem, gate valves.

Regards,
Cockroach

 

[Hidromar]

Hi!

Why not considering a single metal o-ring? this one will be good enough to make a good sealing, working at these temperatures wouldn't be any problem, and also it's a "soft solution" (because deformation) to don't worry about torque pressures

On the other hand, ceramic based seals will work also on such a low pressure

http://www.hidromar.es

 

[aroundhere]

he metal to metal seals I have done was having one side with an angle that when you screw the 2 parts together, the angle meshes together to form the seal. The is how a swageloc works. I always use an oring unless its just not possible due to size or space issues. I believe the part was 17-4 ss and the part with the angle and thredas were 360brass. It was just a fitting type adapter. I didnt believe that the brass would hold up to 10,000 psi, but it did. I would have to go back and make sure it was brass. If you have room, use an oring.

 

[Hidromar]

arounhere

The point with these seals (as far as I hardly know them) is that these seals are not prepared to work under these conditions, I mean, being face seal.

Swageloc system is good while fitting 2 parts (tubes...)

http://www.hidromar.es

 

[europipe]

Why not spiral wound gasket?

 

[HDS]

Is there a pressure vessel seal that would work? Some of them use stainless or copper gaskets. There is probably a nuclear part that does this.

Silver plating gaskets is a good idea at these temperatures.

 

[bcd]

I believe Flexitallic makes Thermiculite gasket material which is rated to even higher temperatures

 

[ShaggyPE]

The ultra high vacuum industry uses a seal methodology called conflat. Have a look a at

http://www.mdcvacuum.com

MDC calls the flange Del Seal.

-Dustin
Professional Engineer
Pretty good with SolidWorks

 

[Hidromar]

Hi!

Just like "brainstorming" (not to be critical)

Europipe: Spiral wound gasket will be good as far as maintenance will be considered, but, I think, this system would be "no maintenance". At the same time, torque tend to be higher, and temperature is a point to take care about. Regarding temperature, you'll need ceramic or metal "wound" but, on both cases, maintenance will be needed.

bcd: Thermiculite, as far a I know, is a "paper gasket" and, even withstanding such a high temperature is a "different" kind of gasket, I think, that the one needed just because it's asking good thermal conduction, and, as far as I know, this seal trend to issolate. By the way, it's a cheap solution (also to take care about)

ShaggyPE: I don't know this one, but, after taking a look at their web site, it seems to be, again, a "copper washer" working as seal. Isn't it?

Have a good day! B-)

http://www.hidromar.es

 

[SnTMan]

Well, as so often happens the OP has disappeared, leaving the rest to speculate on solutions to a problem the details of which are unknown.

Something to do, I suppose