Prediction of safe life of propellants

32 Pages·1.281 MB·English

by  Garman N.S., Picard J.P., Polakoski S., Murphy J.M.

AD-763 879
PREDICTION OF SAFE LIFE OF PROPELLANTS
N. S. Garman, et al
Picatinny Arsenal
Dover, New Jersey
May 1973
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TECHNICAL REPORT 4505
PREDICTION OF SAFE LIFE OF PROPELLANTS
N. S. GARMAN
J. P. PICARD
S. POLAKOSKI
J. M. MURPHY
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3 REPORT TITLE
PREDICTION OF SAFE LIFE OF PROPELLANTS
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N. S. Garman J. M. Murphy
J. P. Picard
S. Polakoski
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IS, AMSTRACT
The measure of chemical stability and the prediction of safe storage life is of prime
interest to the manufacturer and use of propellants. This report will discuss the re-
suits obtained with standard artillery propellant when exposed to artificial ageing at
various temperatures. The measurements of residual stabilizer versus time have been
used as the criteria for propellant deterioration. A kinetic interpretation of this
deterioration phenomena employing Berthelot's Law demonstrates that a family of straight
lines can be plotted characterizing the length of time necessary at the various test
temperatures to obtain a given variation of stabilizer content. By establishing realist c
cut-off points in regard to stabilizer content, propellant safe life may be safely
calculated at any storage temperature.
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KEY WORDS
OLE SWIT ROLE SW T ROLE WY
Propellant
Safe storage life prediction
Propellant chemical stability
Artificial ageing
Propellant stabilizers
Berthelot's Law of deterioration
Propellant stabilizer analysis
Propellant surveillance practices
Propellant temperature resistance
A
Il0kiUtyN CLASSIFIED
Clasesiication
V
Technical Report 4505
PREDICTION OF SAFE LIFE OF PROPELLANTS
By
N. S. Garman
J. P. Picard
S. Polakoski
J. M. Murphy
May 1973
Approved for Public Release: Distribution Unlimited
AMCMS Code 4810.16.2954.1
Propellants Division
Feltman Research Laboratory
Picatinny Arsenal
Dover, New Jersey 07801
TABLE OF CONTENTS
Page
Abstract 1
Object 2
Summary 2
Introduction 2
Results 4
Discussion 5
Conclusions 10
Recommendations 10
References 10
Tables
1. Representation of Arrhenius' and Berthelot's Law 7
2. Propellant Compositions 11
3. Prediction of Propellant Safe Life 12
Figures
1. Stabilizer Depletion Rate for M6 Propellant 13
Conditioned at 900 and 100C.
2. Stabilizer Depletion Rate for M6 Propellant 14
Conditioned at 600, 700 and 800C.
3. Stabilizer Depletion Rate for M9 Propellant 15
Conditioned at 80' and 90*C.
4. Stabilizer Depletion Rate for M9 Propellant 16
Conditioned at 600 and 70*C.
5. Stabilizer Depletion Rate for M30 Propellant 17
Conditioned at 90' and 100*C.
TABLE OF CONTENTS (Cont)
Figures
6. :' bilizer Depletion Rate for M30 Propellant 18
Conditioned at 60%, 70* and 80'C.
7. Stabilizer Depletion Rate for MIO Propellant 19
Conditioned at 900 and 100*C.
8. Stabilizer Depletion Rate for M1O Propellant 20
Conditioned at 600, 700 and 800C.
9. Deterioration Phenomena Expressed by Berthelot's 21
Law for M6 Propellant
10. Deterioration Phenomena Expressed by Berthelot's 22
Law for M9 Propellant
11. Deterioration Phenomena Expressed by Berthelot's 23
Law for M30 Propellant
12. Deterioration Phenomena Expressed by Berthelot's 24
Law for M1O Propellant
13. Comparing Data from Arrhenius'vs. Berthelot's 25
Equations
Distribution List
ii
F
ABSTRACT
The measure of chemical stability and the prediction of safe
storage life is of prime interest to the manufacturer and userof pro-
pellants. This report will discuss the results obtained with standard
artillery propellant when exposed to artificial ageing at various
temperatures. The measurements of residual stabilizer versus time
have been used as the criteria for propellant deterioration. A
kinetic interpretation of this deterioration phenomena employing
Berthelot's Law demonstrates that a family of straight lines can be
plotted characterizing the length of time necessary at the various
test temperatures to obtain a given variation of stabilizer content.
By establishing realistic cut-off points in regard to stabilizer
content, propellant safe life may be safely calculated at any storage
temperature.
OBJECT
To apply standard analytical methods to propellant stabilizer
determination in order to establish the rate of loss of stabilizer
during periods of high temperature propellant ageing, applying
Berthelot's Law of deterioration phenomena to the resulting data in
an effort to predict propellant chemical safe life at any storage
temperature., -
SUMMARY
As part of a project entitled "Long Range Study of Prediction of
Safe Life of Propellants", benefits which may be derived by the appli-
cation of testing procedures or concepts are reviewed and evaluated to
determine their relevance. To this end, the testing technique described
in this report and the kinetic interpretation of the resulting test
data have shown much promise as a method of forecasting propellant
chemical safe life on small samplings of standard single-, double- and
triple-base U. S. Army artillery propellant formulations. However,
work must be expanded to make a more comprehensive review of pro-
pellants of U. S. Army interest and to study and refine the approach
so that full application of this testing routine can be included in
the propellant surveillance effort.
INTRODUCTION
One of the major problems concerned with the manufacture and use
of propellants is the measurement of their chemical stability and the
prediction of their safe storage life. The U. S. Army has substantial
quantities of artillery propellants in storage. These various artillery
propellants are subject to degradation with ageing, the end result
being spontaneous ignition. Therefore, it is mandatory that a con-
tinuous knowledge of the stability status of this stock be acquired.
The Propellants Division, Picatinny Arsenal, has the responsibility
for this mission, and currently maintains control over these stocks
by conducting the 65.5*C. Surveillance Test and the propellant stock
activity described in references (1) and (2) respectively. These
two programs involve all lots of artillery propellant manufactured
for the U. S. Army.
The 65.5%C. Surveillance Test depends upon an end-point which
is defined as the appearance of visible red fumes of nitrogen dioxide
over the propellant sample stored at 65.5%C. It has been established
through years of experience that the development of the end-point in
20 days or less denotes a storage hazard of the ambient stored stock
but with an ample safety margin for disposition action on any remnant
2
of that lot of propellant.
The propellant stock program has only very recently been implemented,
the scope of this activity now relating to propelling charges and/or
bulk propellant actually on hand in Field Service and Industrial Stock
installations. Stabilizer content determinations of representative
samples of each lot forwarded to this installation from the storage
facilities form the basis for safe life determinations of this active
stock. From the data developed by this program, in addition to
those results observed in the 65.5*C. Surveillance Test, a sound,
comprehensive stability control of all U. S. Army propellant stock is
accomplished.
The benefits derived from such programs far outweigh the costs of
testing, in that these measurements are the controlling factor in pre-
venting loss of property and possibly life. The results of these
programs can be translated into money, material and manhour savings
by insuring the use of only acceptable propellant in loading and re-
blending operations, and by reducing storage costs through the dis-
posal of unserviceable propellants. Additionally, a technical advan-
tage is realized from conducting the 65.5'C. Surveillance Test in that
opportunity is provided to perform related studies concerned with the
safe life properties of propellants.
It is widely recognized in the study of propellant chemical
deterioration that the measurement of residual stabilizer content
offers the best means of establishing the stability potential of these
materials. The method of analysis is, of course, of the greatest im-
portance. It must be analytically sound, reproducible, relatively
simple and capable of providing results which can be meaningfully
interpreted. In the last few years, such a method was developed and
is presently replacing some of the older wet chemical methods whose
results were questionable when applied to aged propellants. This method
is described in detail in Reference 3. The available propellant
stabijizer is separated from hot alkali by steam distillation and
analyzed spectrophotometrically. For this, the distillate is diluted
to a standard volume with ethanol and the absorbance of the solution
measured at 285 and or 247 mu for the determination of available
stabilizer as diphenylamine or ethyl centralite respectively. This
method of analysis is employed to accomplish the surveillance activity
described in Reference 2.
Recently the NATO countries were in need of an evaluation pro-
cedure that would assure acceptor countries that propellants receive-d
from others would have a proven chemical stability for a given
period of time Then stored at ambient conditions. After many stability
tests were reviewed and evaluated through the conduct of round robins
to insure that strict analytical agreement could be realized among
3