[PSUBS-MAILIST] anecdotes re: elastomer performance at low temperatures

["Sean T. Stevenson" <cast55@telus.net>]

I seem to recall a discussion a while ago, and memory fails me as to who it 
was with, regarding the effect of extremely low atmospheric temperatures on o-
ring performance in submersible applications.  A brief look at the Parker 
manual indicates that the standard nitrile compounds will perform to 
specifications down to about minus forty degrees (C / F), so one would expect 
that this would be a moot point in submersible operations, with the coldest 
sea temperatures only ever being a couple of degrees below freezing; however, 
atmospheric temperatures can and do dip below the minus 40 degree mark, and a 
submersible sitting on deck in such conditions prior to a dive is presumably 
subject to failure of such elastomers to function as intended if at a 
temperature below their design specification.  Indeed, this effect was 
implicated in the 1986 Challenger space shuttle disaster when the launch went 
ahead on a particularly cold morning despite engineers' reservations.  I am 
curious to know if anyone knows of any anecdotes from submersible operators, 
ROV operators, or ship's crew running submersible gear in extremely cold 
weather, regarding either failure or averted failure of o-rings, gaskets or 
other elastomeric parts due to low temperature, and of any SOP's instituted to 
address this problem. 

Anyone?



************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
	removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************