Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
High temperature resistant nickel base and cobalt
base superalloys are employed as materials for casting or
forging gas turbine blades and vanes. The gas stream in
turbines can contain in the order of 15 per cent oxygen
and have inlet temperatures, for example, in the order of
1700-2300F, creating surface temperatures in the first
: stage blades and vanes averaging 1650F and peaking at
about 1750F. This relatively high speed stream of oxidizing
combustion produced gas is a rigorous environment and
requires parts to be fabricated from these sophistlcated
high temperature superalloys.
Varlous grades of petroleum fuels are avallable
for use in gas turbines~ varying from crude oils to high
distillates and varying in impurity levels of certain trace
.
.
46,411
'
iL4
elements that become part of the gas stream and add
additional corrosion problems to the materials exposed
to the stream. Alkali metals (sodium and potassium)
and vanadium fuel contaminants are known to create such
corrosive problems. The higher grade fuel oils, e.g.
the higher distillates, will ordinarily contain reduced
amounts of these contaminating elements. Water washing
can be employed to reduce the alkali metal concentration,
primarily prior to distillation but also thereafter, since
these are typically present as soluble chloride salts.
Where hot section corrosion is to be held to a minimum,
gas turbine fuel specifications typically limit both the
..
alkali metal elements and vanadium to a maximum 0.5 ppm
by weight. Reducing the hot corrosion in this manner can
be expensive because such fuels may require more treatment
than the more contaminated lower distillates, residuals
and crudes but this expense is balanced against the less
, .
frequent replacement of blades, vanes and other parts,
particularly those in the first stage of a turbine.
Reducing the temperat~re of the gas stream may
also reduce corroslon rates but again must be balanced
; economlcally against lower gas turbine efflciencies.
It should also be noted that alkali metal contaminants are
also known to find their way into the gas stream from
sources other than the fuel. Alkali metal salts are, of
course, present in salt water operating environments. These
salts may be present in the combustion air or combustion
cooling water, particu~arly in marine equipment, equipment
installed on coastal sites or other salty environments.
Studies of the individual high temperature corrosion
~ -2-
: '~
46,411
`
1~856
mechanisms ~or (1) alkali metals and (2) vanadium have
resulted in another use~ul way o~ reducing corrosion due
to these di~ferent individual contaminants. It is known
that alkali metals, whether introduced into the combustion
process in the fuel or inlet air, combine with the sulfur
normally present in the fuel and form alkali metal sulfates
(e.g. Na2S04). When these sul~ates contact the hot alloy
parts, the alloy deteriorates by a mechanism known as sul-
~idation. The addition o~ chromium and certain other metal
element compounds to provide metal oxides (e.g. Cr203) in -~
the gas stream are d~sclosed in the prior art as ef~ective
in reducing or inhibiting hot corrosion of coated and
uncoated superalloy parts due to the aforesaid sulfidation.
The chromium oxide is not known to be effective in
inhibiting the degradation or corrosion due to vanadium ~uel
contamination and intolerable degradation would occur i~
only chromium oxide is added to gas streams resulting from
fuels containing, for example, several ppm of vanadium.
Degradation o~ the superalloys occurs through a dlf~erent
mechanism, best described as gross oxldation, because o~`
this vanadium contamlnatlon. Vanadium ln the ~uel is
oxidized to ~orm molten vanadium pentoxide (m.p. 1274F).
When the pentoxide ~luxes exposed hot metal surfaces such
as turbine blade and vanes or even boiler tubes, rapid ~ ~
oxidation o~ the alloys takes place. The uninhibited ~-
rapid oxidation will rapidly degrade and require early,
costly replacement o~ metal parts so exposed. However, ;
it is known that this oxidation degradation due to vanadium
contamination can be remedied by lntroducing a magnesium
compound into the gas stream. It is believed that magnesium
r
46,411
S~
, .
oxide formed in the hot gas stream reacts with the vanadium
pentoxide to form magnesium orthovanadate (3 MgO.V2O5), a
compound inocuous to the superalloys at normal operating
temperatures of gas turbines and boilers. When alkali metal
,
contaminants, such as sodium and potassium, are also present,
the effectiveness of the magnesium additive is significantly
diminished.
It has been a common practice, therefore, to
remove the alkali metal contaminants from fuels also con- ;-
taining a relatively high level of vanadium contamination
by water washing to a level below which sodium does not
extensively add to the degradation process. Typically, a
maximum of 0.5 ppm of sodium plus potassium is specified
for fuels entering gas turbine combustors. The level of ~
the alkali metal contaminants in the fuel or, more import- `
antly, in the gas stream~ is even more critical if the
vanadium exceeds the typically specified maximum limit of
0.5 ppm in the fuel. The corrosive degradation of hot
section alloy parts when both alkali metal and vanadium are
present in concentrations of more than 0.5 ppm for each
is not merely equal in rate to the rates encountered by ;~
each alone at the given concentration levels but may be - ;
several orders greater than the individual rates added
; together. This undesirable corrosive synergism is believed
to be caused by the formation of extremely corrosive low
melting sodium vanadates, although the study of these
combined reaction mechanisms at high temperatures is diffi-
cult. The aforesaid increased degradation rates, however,
have been experienced. Lower melting corrosive compounds,
it should be noted3 also cause corrosion in a greater number
-4-
; .
~ 46,411
.
-
~ S614
of gas turbine stages.
PRIOR ART ~ -
U.S 3,581,491 discloses ~he attenuation of
sulfidation attack of nickel-base and cobalt-base alloys~:~
in gas turbine engines by treating the gas stream con-
~` taining alkali metal salts with oxides of chromium, tin,
; :: -
samarium and columbium. -
An article by R. C. Farmer entitled IlRx for
: , .
Sodium Sulfidation," appearing at pages 32-35 of Gas
10Turbine Internat~onal, (Vol. 15, No. 5), September-October
1974 discloses Cr2O3 as an inhibitor of sulfidation
degradation due to the sodium contamination of hot gas
- streams in gas turbines and the efficacy of adding to the
fuel a chromlum containing organic compound in a fuel-
soluble solvent. `
An article by S. Y. Lee, W. E. Young and G. Vermes
entitled, "Evaluation of Additives for Prevention of High
Temperature Corrosion of Super Alloys in Gas Turbines,"
appearing at pages 333-339, Transactions of the ASME,
20Journal of Engineering For Power, Vol. 95, Series A,
No. 4, October 1973, dis¢loses certain additive elements, ;~
including magnesium, for reducing corrosion due to vanadium.
An article by S. Y. Lee, W. E. Young and C. E.
.
Hussey entitled, "Environmental Effects on the High-
Temperature Corrosion of Super Alloys in Present and Future
Gas Turbines," appearing at pages 149-153, Transactions
; of the ASME, Journal of Engineering for Power, Vol. 94,
Series A, No. 2, April, 1972, discloses the high temperature
corrosion of certain superalloys due to contaminants in
- 30 fuels.
-5~ ;
,. ..
1~856~4 ~
An article by F.J. Wall and S.T. Michael
entitled "'Effect of SuLate Sal~s on Corrosion
Resistance of G~s Turbine Alloys," appearing at
; . pages 223-245 o Hot Corrosion Problems Associated
~with Gas Turbines, ASTM Special Technical Publication
No. 421 (lg67) discloses corrosion test'results on
. . .
' alloys.'exposed ta sodium.sulfate and mag~esium
sulfate which ~orm a low melting eutectic. .'
~, ' ., The present invention provides a'fuel
additive composition for petroleum fuel oils con~
~ . :
,taminated with alkali metal and vanadium which com~
prises a solution of a petroleum fuel soluble solvent
and compounds of.,chromium and magnesium. Acc~rdi'ng to'
a specific embodiment ~he chromiu~ com~ound, is '- .
chromium octoate... The magnesium compound may be '. '.~
magnesium sulfonate. According to one embodiment o~ ' .;~`
the invention, the composition comprises a petroleum . '.
fuel oil containing more than 0.5 ppm alkali metal,
more than 0.5 ppm vanadium and both chromium and magnesium
in amounts e~fecti~e to inhibit or reduce m~tal degrad-. ;
ation by a gas stream produced by the combustion of the
fuel oil.
The present invention also provides a method of
reducing the corrosion of nickel base and cobalt base
alloys traversed by a hot'gas stream containing both
alkali metal and vanadium contaminants, which method
'`
6 ~
. . . .
,: ' . - ~ .
0l~5614 : :~
.
comprises the step of exposing the stream to a com-
bination of chromium and magnesium. According to one ~ ~-
embodiment, the ratio of chromium:alkali metal in the
fuel is about 4.5:1 and the ratio of magnesium:vanadium
is about 3:1.
It is the primary object of this invention to
provide a composition that can be added to petroleum
fuels having relatively high concentrations of contam-
inating alkali metal salts and vanadium compounds and
thereby decrease the degradation caused by the presence `;
of these contaminants or products thereof in hot gas
~` streams impinging on superalloy combustion chamber or
t ` gas turbine parts. Another object of the invention is
to provide a reduced rate of degradation on turbine vanes
and blades by gas streams produced by combusting petroleum i
: .
uels containing a relatively high concentration of sodium
and vanadium particularly high grade crudes containing
more than G.5 ppm o sodium plus potassium and more than
0.5 ppm of vanadium.
~ hese and other ob`jects are preferably accomplished
with a combination o at least two compounds, one compound
containing chromium and one containing magnesium which are
dissolved in petroleum fuel oils. When the fuel is com-
busted, the added compounds will provide chromium and
magnesium oxides in the hot gas stream. The combination ;~
of these oxides will inhibit or reduce the rapid degradation
otherwise produced because o~ the combined presence of
- 6a -
.
' ~,~'' ' . ' ~
46,411
:3L tD8 5614
,~ , .~ .
relatively high but typical levels of both sodium and
vanadium in Saudi crude fuel (in the order of 3 ppm
; sodium and 5 ppm vanadium). Thus, Saudi crude or other
economical ~ut contaminated fuels containing more than
0.5 ppm alkali metal and more than 0.5 ppm vanadium may
be combusted and employed in gas streams to drive gas
turbines with reduced corrosion or degradation of uncoated .
: or coated blades, vanes or other components made from
nickel base or cobalt base superalloys. :~
BRIEF DESCR:I:PTION OF THE DRAWINGS : ::
Figure 1 is a graphic plot illustrating the
degradation of samples of X-45, a cobalt base alloy, in
several different ~as streams at 1650F; and
Figure 2 is a graphic plot illustrating the
degradation of samples of U-500, a nickel base alloy, in
several different gas streams at 1650F.
~,
,"
,.,!~ ;
, ~.`'1.
,1 . .
,', ' - ' ,
' ~
-7-
.... .. .
, .. , , . . ... . , , . .... ...... ......... ..... ,. . j., .. .. -. . -.. ..... ... . . .... . ..... .. .. . ... ~
46,411
S~
DESCRIPTION OF THE INVENTION
We have dlscovered that the unusually high rate
of degradation of nickel base and cobalt base superalloys
when sub~ected to gas streams resulting from the combustion
of petroleum fuel oils containing more than 0.5 ppm of
alkali metals (sodium plus potassium) and more than 0.5 ppm
of vanadium can be reduced, preferably by the addition of a
combination of a soluble chromium compound and a soluble
magnesium compound to the ~uel oil prior to combustion.
While water washing is a relatively convenient and inexpenslve
way of reducing the alkali metal concentrations to levels be-
low 0.5 ppm (because the alkali metals are present as water
soluble salts), there may be areas where the readily avail-
able wash waters are themselves contaminated with alkali
metal salts, thus precluding effective water washing.
Already washed ~uel may be later contaminated by residual
alkali metal salts due to the purging of tank cars, tanks
and pipelines with sea water. An ability to use fuels such
as several light Arabian crude oils and particularly Saudi
20 crudes whlch have more than 0.5 ppm o~ sodium plus potassium ~;
,.~
and more than 0.5 ppm o~ vanadlum ln the absence o~ potable
wash waters would be desirable if the high temperature
corrosion could be reduced.
In accordance with our invention both chromium
and magnesium are added to or preferably dissolved in the -
contaminated ~uel oil. Magnesium, in the form of oil
soluble organic salts such as magnesium naphthenate or
magnesium sulfonate is added to the ~uel oil to preferably
provide a weight ratio o~ about 3:1 o~ Mg:V. (A11 concentra-
`30 tions and proportio~s herein are on a weight basis unless
.
., :
.. . .... .. .,.. . ... ., . - .. . -.. , .. , .. , . ,.. .... , . .. . ; , ", , .: .. ,.. , ", .,, ~ , .. ;:
46,411
8 ~ 6
,~
otherwise stated.) Chromlum, also preferably in the form
of an oil soluble organic salt such as chromium octoate, is
also added to the fuel oil, preferably in an amount to pro-
vide a ratio of about ~.5:1 of Cr:Na+K. The ratios of
Mg:V and Cr:Na*K may vary considerably ~rom the preferred
ratios and yet provide the advantages of reduced corrosion
or degradation. The use of fuels with lower than preferred
ratios of Mg:V and Cr:Na+K may result in an undeslrable more
frequent gas turbine blade and vane replacement but the
presence of even these lower ratios of our combined additives ; -
will provide a long~r life than would be obtained wlthout
our additives. Ratios higher than the expressed preferred
ratios should provide the full advantages of reduced corrosion,
indeed may permit even higher than currently recommended
inlet gas and blade temperatures, but suffer the dis-
advantages of more copious deposlts within the turbine.
Consequently more frequent washing away of deposits on the
gas turbine parts would be requiredO The disadvantages of
these copious deposits would also be present if, for example,
fuel oil~ containing 10 or even 100 ppm o~ vanadium was
present in the fuel oil and even the preferred ratio of
Mg:V was employed. The advantages of reduced corrosion would
nonetheless be obtained.
The most convenient method of in~ecting our
additives into the fuel oil is by means of a solution of the
magnesium and chromium in a solvent which is in turn soluble ~ ;
in the fuel oil. This solvent may be a high petroleum fuel
distillate orJ preferably, a fuel soluble solvent such as
kerosene, mineral spirits or benzene. These latter solvents
have significantly lower pour points and viscosities and
_g_ ~ .
Ll6, 411
1a~8561~
'`':" '
provide solutions which can be more easily pumped, poured
and otherwise handled. That ls why we pre~er as an additive
composition a solution of chromium and magnesium compounds
in a fuel soluble solvent~ The concentration of chromium
and magnesium in the solution is not critical. For
convenience in reducing the volume of solution to be
handled, relatively high concentrations are advantageous.
Chromium octoate and magnesium sulfonate can be dissolved -~
- in relatively common and inexpensive oil soluble solvents
to provide a solution containing about 8 percent chromium
and 8 percent magnesium. Solubility of various organo-
metallic compounds containing either chromium and/or magnesium
can be easily determined by trial. Petroleum solubility of
.
solvents ~or these compounds can be similarly determined.
It should also be understood that the relative
proportions of chromium and magnesium in the oil solublesolution
may be formulated or des~gned to provide the preferred ratios
o~ 3 Mg:lV and 4.5 Cr:l Na+K where the proportlon of V:Na+K
in the fuel is known~ More specifically, for example, ~or
a Saudi crude consistently containing 3 ppm sodium plus
potassium and 5 ppm vanadium, the weight proportion o~'
chromium to magnesium would be 13.5:15 in the oil soluble
solution. That one solution could be added to the Saudi
i; . . .
crude fuel oil, in a predetermined measured amount, with the
knowledge that the two preferred ratios are accommodated so
long as the concentration and proportion o~ sodium plus
potasslum and vanadium did not significantly change. Where
:` the contaminating constituents vary extensively either in ~`
conc~ntration or proportion it may be more convenient to
employ two separate oil soluble solutions, one containing
:' -1O- ;
.,
.. :
- . , .. . , ., . ~ . ., .- .;.. ~ .. .. . . . . ... . ..... .. . ..
46, 4
~L~856~4 :~
magnesium, the other chromium and then varying the pro-
portions of additions in response to the changes.
The possibility of alkali metal contamination
in the hot gas stream from sources other than the fuel oil
or in addition thereto should also be recogni3ed. In
coastal and marine installations~ alkali metal contaminants
may be introduced in the air employed for combustion or in
water that may be in~ected into the combustion chamber to
control the flame temperature. Regardless of source, the
alkali metal contamination in the gas stream, together with
the vanadium contamination, will cause rapid degradation
of the superalloy parts. This degradation or corrosion can,
of course, be reduced or inhiblted by adding the combination
of soluble magnesium and chromium compounds to the ~uel oil.
` ~he concentrations and proportions of the magnesium and
chromium in the fuel shouId be selected to provide the
hereinabove described preferred ratio of Cr:Na~K taking into
account all of the alkali metal which may find its way into
the gas stream regardless of source. This may be done, for
example~ by measuring the sodium plus potassium in the com-
bustion air and converting that into an equivalent concentration
in the fuel. This back calculation is relatively simple f;
since fuel:air ratios are known.
Although we believe that the addition of the
combination of chromium and magnesium is most conveniently
effected with soluble compounds in the fuel, it should be
understood that other modes of introduction and other com-
pounds may be employed so long as the result is the inclusion
or in~ection of the combination of the chromium and
magnesium in the hot gas stream to negate the corrosiveness
',
,
~856:1.4 r
o~ the alkali metal and vanadium present in the stream~
It is, of course, the contaminants in the hot gas stream
that cause the co.rrosion of the superalloy components. - The
combined chromium and magnesium additions could with greater ;~`
difficulty be made by injecting the compounds directly into -~
thç combustion chamber or with the stream of air for the ~:
comhustion. The benefits of our invention would also be
iprovided, for example, by coating the exposed metal par~s ;~
;with a material containing both chromium and magnesium. .~:
Inaeea, the benefits of red~ced corrosion may be obtained . ;~
wherever combustion product gases containing both alkali ;~
~metal and vanadium con~aminants (a~ individual l~vels . :
equivalent to about O.S ppm in the fuel) impinge on compo~ents
fabricated ~rom nickel base or cobalt base supe~alloys.
Returning now to the gas turbine speciically.and
the use of fuels containing more than 0.5 ppm of alkali metal
and 0.5 ppm of vanadium ~or gas streams containing ~hese - ~-
elements in equivalent levels~, we prefer to provide ~hromium
in.the fuel i~ an amount so that the ratio of chromium to
alkali metal is about 4.5:1 and magnesium in ~he fuel in
amounts to provide a ratio of magnesium to ~anadium o~ about
.3:1. Employing these fuels in gas turbines with blades o
nickel base superalloys and vanes of cobalt base alloys,
satisfactory first stage life can be obtained at average blade
and vane temperatures of 1650F and spot peaks o 1750F.
In present day commercial gas turbine technology nominal inlet
gas stream temperatures of about 2070F are consistent with
the above first stage metal component temperatures and the .
gas stream temperatures may vary from nominal ~300F.
We have conducted corrosion tests in a laboratory
.
- 12 -
:
L~ 6, 4 11
`"
` ` 1~8S6~ ~
':
turbine simulator where samples of commonly used gas
turbine nickel base and cobalt base superalloys are exposed
to gas streams containing vanadium and sodium contaminants.
The fuel employed in these tests was a No. 2 petroleum
fuel oil distillate containing, according to specification,
less than 0.5 ppm of either sodium or vanadium. To simulate
a crude of the nature heretofore described, the actual
concentration of both of these elements in the test distillate -
were determined analytically. Then, test sample levels of
10 sodium and vanadlum were provided by appropriate additions ~ ;
of sodium carboxylate and vanadium carboxylate to the test
fuel oils. The test fuels also contained 0.5 percent
sulfur. Chromium was added to the fuel test samples as
chromium naphthenate. Magnesium was added as a fuel oil
soluble solution known as KI-16, commercially available from
the Tretolite Division of Petrolite Corp. Dosages of the
; additives provided fuel test samples havi.ng Cr:Na ratios of
4.5:1 and Mg:V ratios of 3:1. Oxidation results were
obtained with natural gas which does not contain sodi.um or
vanadium. The alloy test samples were 1/4" dlameter pins.
The pins were mounted in a high pressure corrosion test
passage where they were exposed to test gas streams ;
; characteristic of those encountered in gas turbines. Additional
details of the test facility and operating procedures are
disclosed by S.Y. Lee, S.M. De Corso and W.E. Young in an
article entitled "Laboratory Procedures for Evaluating High- ;
Temperature Corrosion Resistance of Gas Turbine Alloys"
appearing at pages 313-320, Transactions of the ASME, Journal
of Engineering for Power, Vol. 93, Series A. No. 1, July, 1971
3~ and incorporated herein by reference. The article also
-13-
~ ' ''
~L~856~4
,` . ':
sets forth the compositions of nickel base and cobalt basP
superalloys. Corrosion results in descaled metal weight
loss and metal diameter recession rates were measured.
Results of tests at 1650F on X-45, a typical gas
; turbine vane alloy and ~-500, a typical rotating blade alloy
are illustrated graphically in Figures 1 and 2, respectively.
The test resul~s confirm a significant reduction of corrosion
rate due to vanadium and sodium ~uel contaminants when our -
combination of magnesium and chromium was also included in
the-fuel. Indeed r the combination of chromium and magnesium ,
additions give some degree of protection to superalloys rom
the simple oxidation that occurs in tests employing con-
taminant-free natural gas. The e~feçtiveness of the adaitives
applies equally well to various nickel base and cobalt base
.
;superalloys used in gas turbine engines. The additives are
efficacious with coated blades and vanes as well.
. . ~ . '
~ dditional test results confirming the e~ficacy
of the combined magnesium and chromium ~dditions in the
pre~erred Cr:Na and ~g:V ratios are summarized in Tables
1 and 2.
~ ~.
- 14 -
'.
.
~' ' :
- ~0~3~i61~L ~
TABLE I - CORROSION RATE IN WEIGHT LOSS
~a) Result at 1~50F with fuel containing 3 ppm sodium an
5 ppm vanadium ~reated with chromium and magnesium
additives.
Corrosion r~te expressed as weiqht loss, Mq/cm~
A~LOYS 115 hour result 300 hour resul~
_ . , - .
-X-4~ 4.74 or 0.041/hr 3076 or 0.013/hr
:: : , , . ............ . _ . . _ : :
U-500 4.72 or 0.041/hr 9.70 or Q.032jhr :
' . ~ , _. '~'' '
U-520 4.75 or 0.041/hr ~.13 or 0.007/hr. . ,, _ , ~ . _ .
~ ~ ECY-768 4.62 or 0~04/hr 5.68 or 0.019/hr
'~ . , . ._ ._, , , . _
(b) Result at 1500F with fuel containing sodium and
vanadium not treated wit~ any additive.
Sodium and aorrosion rate i~ 150 hours of
Vanadium testing 2
Level ALLOYS Weight loss, Mg/cm
: _ _ . . . r - . _ ~ . . .~ :
5 ppm Na X-45 36.0 or 0.240!hr ~ ;
. . .. . ..
2-ppm V U-500 56.6 or 0.377/hr
.', ~ ,. . . ,, ._ . ,
2 ppm Na X-45 _ 12.2 or 0.081/hr
2 ppm V U-500 12.1 or 0.81/hr
. . ,
..
~c) Result at 1600F with uel containing no sodium or
; ~anadium. Additives not used.
Corrosion rate expressed as weight loss, M~cm2
ALLOYS
115 hour result 1 300 hour result 500 hour,result
, _ . .
X-45 7.5 or 0.06S/hr 13.9 or 0.046/hr 16.6 or 0.033/hr
i. . . .: . I
U-500 7.2 or 0.063/hr 1~:`6 or G.034/hr 15.5 or 0.031~hr
.~ _,, . . ' _ 1. ' ' '.'
'
~ :
.
- . . "" . . .. ~. ;., .. .... " .,, ;. ~.. ,., ;. .
56~4
. ` :'
TABLE 2 - CORROSION RATE AS METAL LOSSES
(a) Result at 1650F with fuel containing 3 ppm soaium and ~;
S ppm vanadiu~ treated with chromium and magnesium
; additives.
. . .
~__ _ _Diametçr metal recession, mils j
ALLOYS 115 hour result 300 hour resul~
~ . ,~ . , ;~ ,
~ 45 0.7 or 0.0061~hr 1.2 or 0.004~hr ~
: . . -................. . '. '. ~'; ' .
U-500 0.9 or 0.0078/hr 1.2 or 0.004/hr
~ .. ,.... ~ , ~, . . _ _ . -
~-520 1~3 or 0.0113/hr 1.2 or 0.004/hr
_ _ .T . ' , ~ , .
- ECY-768 1.3 or 0.0113/hr 1.3 or 0.0043/hr
!
~b) Result ak 1650F with a fuel containin~ 5 ppm Na and ~ ;
2 ppm V without additive treatment. - -
Diameter metal recession, mils -
ALLO~S 102 hour result 250 hour xesult 400 hour result ~
. , . .................. ... _._ . , .~ I ' .. ~: .
~ ~ X-45 13.8 or 0.1353/hr __ 26.1 or ~.0653/hl
.. ...... ___ , ~........... _ ,, , ~ ... .. ~,.; i .
U-500 12.3 or 0.1206/hr 37.6 or 0.1504/hr ~___- j
_ . . , , _ .. .
~c) P~esult at 1650F with a uel containin~ no sodium
or ~anadium. Additives not used.
~LL~YS Diameter metal recession in 298 hours, mils
X-454.1 or 0.0138/hr ~~
_ . A _ .. _.. : . .. . '
U-500 5.0 or 0.0168/hr
'.
- 16 - - ~
.
.:
,
.:
~' ' ' -:.
.. .. . , ,.,, . , . , .. . - ::
~C~l5 56
.
An additional advantageous feature o~ our
invention applies to fuels which al~o contain
lead as a contaminating element. Lead contamination
may occur where petroleum fuel oils are shipped
or transpoIted in tanks where gasoline residuas
remain. The magnesium additive is effective in
re2ucing corrQsi~n degradation ~ue to lead fuel
con~amination. If present, the concentration of .
the lead can be added to the concentration of the
vanadium and the amount of magnesium to he added
. will be determined ~rom that sum.
:
:
'
.
~ .
: ' , , . ~ '
` ' '`' ~;
- 17 -
`' ' '~
,.: .
