Low pressure seal for Compressed Air 1

[mdossaji]

This is a two stage reciprocating compressor. The intercooler heads (aluminum) are bolted to the cast iron inlet heads with an aid of a aramid fiber gasket. I seem to have noticed that the gasket cannot seal the oil vapor released during compression. The pressure is 65 psi, temp= 250F. The heads are torqued using two 1/2-13 bolts at 4" apart. I did some pressure film test and it was obvious that the center part of the flange had very little compression. Any recommendation of gasket material and thickness?

 

[unclesyd]

Without a lot more details your best bet is to try sheet Gore-Tex (expanded teflon). A little expensive, but will do the job 95% of the time. I would try a 1/8" thick material. Check with a local gasket supplier as they should have a piece laying around.
If the bolts are not bottoming out you might have to use a liquid sealing compound used around cars.

You might want to look a set in stud and nut

Is the Al flange warping?
What grade bolts are you using?
How good are the CI threads?
How much sealing surface do you have on the Al flange(width)?

http://www.gore.com/sealants/english/

Good luck

 

[mdossaji]

We have tried goretex GR 1/16" thick (as recommended by Gore) but have had no success. The Al flange is definitely warping due to the fiber gasket's compressibility. The bolts used are grade 5. The CI threads are very strong. We normally yield the bolt before the CI threads strips. The thread hole in CI head is a thru hole.

 

[unclesyd]

Back to square 1.
Looks like you don't have enough Al flange.

Are the bolts causing the warpage of the flange?
Let the gasket come outside the bolt circle to keep tne moment off the flange.

Check the following website look at the heavy grade.

http://www.hylomar.co.uk/msdstemp.htm

I need to check on another possibility other than adding metal to the Al flange.

 

[JP0506]

With the gasket material smear a light film of grease on both sides of the gasket ( just coat the fingers and rub into gasket, don't over do it ), you will notice a slight change in colour of the gasket as the grease is absorbed, this softens the material and allows for greater compression and tends to take shape of the two mating faces much better.

 

[mdossaji]

Thank you all for your input. I went ahead and used klinger B-6287 controlled swell gasket. It took care of my problem and was able to reduce the torque due to the higher compressibility of the gasket.