Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Exhaust flange sealing

Exhaust flange sealing

Exhaust flange sealing

I have built a one off exhaust system and the sections of pipe and manifold are joined with bolt together flanges.

I would like suggestions as to how to seal these flanges. My thoughts are for a silicon sealer, gasket sealer or a gasket material.

Pictures of my application can be viewed

Thank you


RE: Exhaust flange sealing

I use ordinary 3-hole header gaskets with excellent success on my fabricated exhaust systems.  Unfortunately your flanges are not standard header size.  Perhaps the material is available in sheets so you can cut your own.  McMaster-Carr may be a source?

RE: Exhaust flange sealing

Silicone sealant works fine so long as it is close to a water jacket, like pipe to head flange, or down around the collector flange or further back


RE: Exhaust flange sealing

Like Pat, I often use one of the high temp RTV's on the flange to head surface (THIN film) but the last several headers have had 1/2 inch flanges instead of the usual 5/16 inch material and, as surprising as it sounds and, with proper matching, the header to head pipe connection has needed NO gasket at all.  The half inch plate is not very heavy once it is fabbed into a standard three bolt shape.  I just used a standard flange as a template. Oh yes, I also went  to 3/8 inch SS bolts and nuts on the flange plates.
I have heard, from one of the local drag racer types, that on SBC's  the thicker plate results in the header assm  not loosening as often as thinner plates---seems logical.

Point of fact---I generally use a slip fit on any exhaust systems on the vintage road race cars.  They sit to low for clearance of a big flange and rules ban floorpan mods.


RE: Exhaust flange sealing


try Welltite. It is a cousin to Hylomar and was discovered/invented to seal WW2 tank head gaskets. I have not used it personally but it gets rave reviews in the UK.

BTW...you dont have Mcmaster-Carr over your way.

As a suggestion if you do another exhaust system, make the flanges a little thicker. Use .062" compressed asbesos sheet and cut your own gaskets. If compressed asbestos sheet is no longer availiable over your way, use other high temp material of at least 600 F.

Also instead of flat flanges you can use Marmon clamps...rock on over to Demon Tweeks and see what they have....a lot cleaner but more $$$ (lbs.)

good luck

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close