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From: rollhaus@dtoa3.dt.navy.mil (Rollhauser)
Newsgroups: sci.military
Subject: Re: USS IOWA
Message-ID: <1990Jun28.025910.19410@cbnews.att.com>
Date: 28 Jun 90 02:59:10 GMT
References: <1990Jun11.211201.18187@cbnews.att.com> <1990Jun27.021058.1535@cbnews.att.com>
Sender: military@cbnews.att.com (William B. Thacker)
Organization: David Taylor Research Center, Bethesda, MD
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From: rollhaus@dtoa3.dt.navy.mil (Rollhauser)

Steve Creps writes, "I thought Sheffield was lost because she was
    made of aluminum, which was ignited by the burning missile (metallic Al
    will burn at high enough temperature.)"

	 The Type 42 Destroyer (Sheffield) was not constructed with
    extensive aluminum structure, so the fire resistance of aluminum did
    not really affect the performance of this ship. (Lots of people are
    under the impression that the Sheffield was aluminum.)
	 The missile that hit Sheffield hit in an unfortunate place (the
    junction of three fire zones. It did not explode but spread fire over a
    large area. Being a modern ship, Sheffield was equipped with
    miles of electrical cable, tons of paint, and lots of "habitability
    materials," all of which was closely compacted for easy ignition. (This
    stuff helped cause enough smoke and toxic fumes to impede the most
    dedicated firefighters.) Key control positions had to be abandoned due
    to smoke.
	 Some fire pumps couldn't be operated, and there wasn't enough
    pumping capacity remaining to fight the fire. Breathing apparatus ran
    out of air. Eventually, fire spread near the magazines, and Sheffield
    was abandoned. She was finally sunk by the Royal Navy.

[mod.note:  I recall an article some time ago in USNI Proceedings, which
gave a large share of the credit for saving the USS Stark to the timely
arrival (by helicopter) of extra air tanks for the firefighters.  - Bill ]

	 Aluminum does burn, but I haven't seen any evidence of this
    happening in a shipboard fire. Aluminum melts at about 1200 degrees F.
    In the fires I've set, it just drips down onto the deck and forms a
    puddle. (BTW there are two ways to extinguish a metal fire: 1) exclude
    air by covering with sand or special Class "D" extinguishing agents, 2)
    cool it by applying lots of water (from a distance.))


	 Nigel Tzeng writes, " Hmmm...isn't steel harder to ignite than
    aluminum?  Isn't this why the Navy is starting to steer away from
    aluminum superstructures?
	 "I've heard that's its near impossible to put out an aluminum fire
    but I have no idea how true this is...anyone who knows for sure?  The
    Stark seemed to have survived a fire but the Sheffield didn't."

	 The official reason for the USN's decision to discontinue
    use of aluminum in deckhouses is the poor performance of the material
    in a marine environment. Several ship classes had stress cracking
    and/or corrosion problems that were a maintenance headache. Modern
    corrosion resistant steel designs were seen as a way to reduce life
    cycle costs. Increased survivability of a steel deckhouse... well at
    least the steel won't melt.  

	Chuck

    Standard Disclaimer: My opinions, not the Navy's