Henry:
Long ago, I asked for this question to be resolved: a very well known
Aerospace consulting organization that did the work could not find any
significant difference between the Soviet and US Titanium; nor, in limited
testing, were they able to duplicate the previous American work with either
American or Soviet Titanium.
But one’s bottom is better covered if you follow ASTM....
Bill
On Mon, Mar 15, 2021 at 12:48 PM Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Mon, 15 Mar 2021, William Claybaugh wrote:
The Antares launch vehicle uses dozens of Titanium high pressure He
tanks *inside* the Lox tank. Neither that vehicle nor the hundreds of
Russian and Soviet heritage designs have ever had a failure caused by
the presence of Ti in a Lox bath.
However, quoth ASTM's "Safe Use of Oxygen and Oxygen Systems", 2nd ed.,
2014, p. 48:
"Restricted Alloys
"In oxygen systems, the use of certain metals, including titanium,
cadmium, beryllium, magnesium, and mercury, must be restricted. Titanium
alloys are generally avoided because they exhibit very undesirable
flammability and ignition characteristics. Tests have indicated that
titanium, α-titanium, and α2-titanium alloys can be ignited and sustain
combustion in oxygen at absolute pressures as low as 7 kPa (1 psi). A
reaction of titanium and LOX or GOX may propagate and completely consume
the metal [11,64–66]. Various titanium alloys tested (α, α−β, β alloys)
have shown very high sensitivity to mechanical impact in oxygen [55].
Frictional heating tests conducted on titanium and titanium alloys
indicate that the Pv product for ignition is extremely low (Table 3-5).
Recent tests indicate that titanium and its alloys also can be ignited in
air in frictional heating tests. In addition, titanium particulates are
extremely flammable and are exceptional as particle impact ignition
sources."
So, not absolutely out of the question, but not generally considered a
good idea.
Henry