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From: rollhaus@dtoa3.dt.navy.mil (Charles Rollhauser)
Newsgroups: sci.military
Subject: Re: DDG-51
Message-ID: <1991Jun6.063244.5654@amd.com>
Date: 3 Jun 91 17:08:05 GMT
References: <1991May31.061148.13091@amd.com> <1991Jun1.012802.27928@amd.com>
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From: rollhaus@dtoa3.dt.navy.mil (Charles Rollhauser)


fcrary@lightning.Berkeley.EDU (Frank Crary) writes:
> Why does the Burke have an all steel design? I had thought all
> recent ships used aluminum?

... discussion by several posters as to burning characteristics of
	aluminum, citing Belknap, Sheffield, and British frigates.

norton@manta.nosc.mil (LT Scott A. Norton, USN) writes:
> NO, NO, NO!  Sheffield was all-steel.  Also, the missile hit in the
> main hull, slightly above the waterline.  The fires were due to
> flammables such as electrical cable insulation.

While theoretically aluminum could burn, there has been no documented
evidence that it will burn in shipboard fires. In most cases it will
weaken, collapse, and possibly melt at temperatures lower than would
happen with steel structure.  While these are obviously undesirable
characteristics in a warship, the problem is nowhere as bad as it has
been made out to be.  When Belknap was recommissioned, she had a new
ALUMINUM deckhouse, with high temperature insulation protecting vital
structure. (The accident - collision with the Kennedy, and the dumping
of hundreds of gallons of fuel onto the superstructure - caused a fire
involving flammables carried aboard every ship.)

> ....Aluminum-qualified welders are not as common as steel welders.

LT Norton hit the nail on the head when he cited maintenance problems
as the reason aluminum deckhouses have been abandoned by the USN. The
problem is this: Structural aluminum is not the same as the stuff of
beer cans and rain gutters; it gains strength by heat treating. Welding
aluminum is an art in itself, and when it is welded it looses a
substantial amount of strength, unless properly heat treated.

Sielski gives an account of the history of aluminum as a Naval
structural material, and the reasons for its elimination in combatant
ship design in "The History of Aluminum as a Deckhouse Material," in
the Naval Engineers Journal, May 1987 Vol 99 No 3, pp 165-172.

Chuck