Joint compound for exhaust hot section replacement

[ddomino]

In the process of troubleshooting a recalcitrant A4 to get it to start I found a small leak in the exhaust system at one of the manifold flange bolts. After unwrapping the insulating heat wrap from the first iron pipe section, I also found significant corrosion on the pipe, and the flange itself had also sustained some damage. I ordered a new flange from Don and have located the appropriate 1 1/4 in galvanized pipe nipple to use as the replacement. However, I was concerned about creating a good seal for the new connections and I'm looking for a recommendation for a pipe joint compound that will withstand the high temperatures just leaving the manifold. Anyone have any specific suggestions?

[msauntry]

Just did this in September. I greased the threads with the ubiquitous jar of Lanocote I keep on the boat. You just need something to lube it while you're spinning on the pieces.

[ddomino]

Ok, thanks. I see from web info that it has a reputation for ensuring that parts will still come apart after being attached for lengthy periods, a definite plus for parts you don't expect to mess with very often. But just to verify, it will retain those characteristics under high temperature, as well as providing a seal against CO blowing by the threads? No apparent issues in high temp applications?

dd

[rigspelt]

I see from my notes made while researching this point for my upcoming dry stack rebuild that one well known guru uses never seize to get the joints tight, allowing the pipe threads alone to do the sealing work.

[ddomino]

Ok, in addition to the two suggestions helpfully provided above, here's another that seem to fit the application, Slic Tite thread sealant. The company-provided data indicates specific capability in high temperature applications and long non-drying characteristics for easy future disassembly. Product details are available at http://www.laco.com/productDetail118.aspx. Does anyone have any experience with this product?

[msauntry]

The tight fitting pipe threads should provide a fine mechanical seal. The lube just helps the pieces spin on all the way. In spite of it, I seriously doubt my pipes will ever come apart again. I'm never that lucky! The high temp product certainly can't hurt, but I wouldn't go out of my way to acquire it.

[ddomino]

Yeah, I'm probably being a bit anal about the whole thing, but carbon monoxide kinda freaks me out..anyway I'm going to go with the Slic Tite. Both local plumbing supply houses carry it so easy enough to find. Thanks everyone for your input.

dd

[rigspelt]

carbon monoxide kinda freaks me out

Me too - importance of a good blower/ventilation system.