Date:         Wed, 28 Nov 2001 18:50:43 EST
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Re: Missing Exhaust bolts
Comments: To: lkadams@telusplanet.net
Content-Type: text/plain; charset="US-ASCII"

In a message dated 11/28/01 3:29:26 PM, lkadams@TELUSPLANET.NET writes:

<< http://gerry.vanagon.com/cgi-bin/wa.exe?A2=ind0012B&L=vanagon&P=R12840 >>

Keith,

As a practicing chemist myself with extensive experience with Stainless
(particularly 304 and 316) I must say that I'm in vigorous agreement with
both your current and your archival post.

The last way I would describe stainless is to say that it was brittle. In
fact if anything the grades used in SS bolts tend to flow or elongation,
particularly at elevated temperatures. Nonetheless, this material performs
superbly to temperatures in excess of 450C. At this point it can react with
hydrocarbons (modest rates) and water (high rates) leading to hydrogen
embrittlement. This is the internal failure mode seen in SS mufflers mounted
on a Vanagon exhaust with afterburner (rich mixtures and short length pipe
phase resonances - putting hot gases in a high pressure zone outside the
head, often at the entrance to the muffler). Got nothing to do with bolts
sitting outside in atmospheric oxygen and water vapor. The key to stainless
is the protective oxide film.

I only use stainless connectors, tubing, bolts and mufflers so long as the
opportunity presents itself.

Brittle! Humbug!

Frank Grunthaner