[alfa] Stainless fasteners in exhaust systems

["Jay Mackro" <jmackro@xxxxxxxxxxxx>]

Dean Cains had suggested:

> If you want a trick to make the exhaust installation a bit easier, buy a
> set of stainless steel nuts, bolts, and washers for the connection between
> the manifolds and the downpipes.  Weld .....

I had tried something a bit simpler, and had some strange results.
My '76 spider has a catalytic converter attached to the exhaust
pipes with two, three-bolt flanges.  I figured "hey, SS is the way
to go", and bought some 5/16" X approx. 2-1/2" stainless bolts,
nuts, and lockwashers.  I needed to remove the cat a couple of
months later, and tried to loosen the six bolts.  Two of them were
locked up - totally frozen.  The bolts fractured before the nuts
would loosen.  No they didn't look corroded, and no, I hadn't
used Loctite or anything else on the threads.

My question for all you metallurgists out there is: Does stainless
steel tend to "gall" or otherwise  lock up, especially when exposed
to heat?  Should I have used oil, anit-seize, or some other lubricant
on the threads (of course, would that have survived the heat of the
exhaust system?).  I replaced the SS nuts with regular steel ones,
but retained the SS bolts.  My hope is that this combination will give
the desired result.

Jay Mackro, San Juan Capistrano, Ca.
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