|
Items in cart [0] |
Questions? Call 888-624-8373 |
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 58
Appendix B
Leakers by Munition Type
MC-1 GB BOMBS
Metallurgical analysis carried out by the Army Ma-
terials and Mechanics Research Center to determine
the cause of GB leakage in MC-1 750-lb bombs deter-
mined that weld crater cracks, as well as other weld
defects such as porosity, cold cracks, and incomplete
weld penetration, provided a continuous leak path (U.S.
Army, 1986a). An example of one of these defects is
shown in Figure B-1.
Additional leakers resulted from a poor fit of
threaded alloy steel plugs into the tapped holes that had
been drilled to obtain samples for analysis as part of
the SUPLECAM program. This problem is limited to
those known units from which samples were obtained
in this manner.
155-MM GB PROJECTILES
GB 155-mmprojectiles were examined with the fol-
lowing results (U.S. Army, 1984a, 1985a):
.
.
· Cracks were found in the welded joint between
the burster tube and shell of one sample, probably
allowing leakage.
The evidence strongly suggests that the brazing al-
loy line defects constitute a major cause of the GB leak-
age for 155-mm GB projectiles with two-piece burster
tubes. As discussed below, similar defects were ob-
served with 105-mm GB projectiles having two-piece
burster tubes.
105-MM GB PROJECTILES
In three samples with a two-piece burster, a large
amount of porosity was observed at the brazed
joint between the burster tube and the sealing
plate; this allowed leakage.
The region of the press fit exceeded the specified
surface roughness in a sample of a one-piece
nurster, which might allow some leakage.
Twelve GB 105-mm M360 projectiles were exam-
ined in 1981 as part of the Stockpile Reliability Pro-
gram (U.S. Army, 1983~. Six of these projectiles were
nonleakers, one had never been filled with chemicals,
and five were leakers. Projectiles that had leaked were
those with two-piece burster tubes in which an end plug
of resulfurized steel was brazed to the main casing sec-
tion. The agent had leaked through defective (porous/
incomplete) brazed joints and reacted with moisture
and air, leading to agent hydrolysis. This in turn made
the agent corrosive and resulted in attack of the steel at
the braze metal and at the sulfide stringers in the end
plug. The brazed metal-steel junction may have caused
some galvanic attack, which in turn may have increased
the damage to the steel at the edge of the brazed joint.
In this case, the initial leak of agent was through a de-
58
OCR for page 59
APPENDIX B
59
FIGURE B-1 Crater crack in MC-1 750-lb GB bomb. Source: Lis A. Wachutka, Soldier and Biological Chemical Command,
Stockpile Management Team, sent by e-mail March 19, 2002.
fective brazed joint to the inside of the burster. In time,
this led to corrosion of the end plug and an increased
leak path. The units with one-piece burster tubes had
neither the brazed joint nor the resulfurized steel end
plug and therefore did not have this problem.
8-INCH GB PROJECTILES
A comprehensive metallurgical analysis of three
leaking 8-inch M426 GB projectiles was conducted to
determine the cause of agent leakage (U.S. Army,
1984b). A through-the-wall crack was observed in the
nose end of one of the leaking projectiles. In the other
two leaking projectiles, a through-the-wall crack was
observed in the burster tubes. These cracks were the
cause of agent leakage. In the first case, GB agent
leaked from the inside of the shell to the exterior. For
burster tube cracks, agent leaked from the exterior to
the interior of the tubes. In all cases, manufacturing
defects were thought to be responsible for the cracks
rather than corrosion. The shell crack most likely
formed during the press-fitting of the burster tube into
the shell due to the combined effects of preexisting
surface flaws and the generation of hoop stresses. The
burster tube cracks resulted from improper fabrication
procedures.
M55 GB ROCKETS
M55 GB rockets have an aluminum alloy warhead.
GB agent reacts with the aluminum, causing general
corrosion, pitting, and, eventually, leakers. Leaking
rockets were first found in 1966 (U.S. Army, 1966).
As discussed earlier in the chapter, four subtypes of
GB were loaded into various lots of M55 GB rockets
(U.S. Army, 1985b). In 1985, the Army found a direct
correlation between leakers and the subtype of GB
agent filled into the rockets, as shown in Table B-1.
OCR for page 60
60 EFFECTS OF DEGRADED AGENT AND MUNITIONS ANOMALIES ON CHEMICAL STOCKPILE DISPOSAL OPERATIONS
TABLE B-1 M55 Rocket Leaker Detection by GB Agent Type
Type of GB Number of Number of Number of Percent of Stockpile
Agent Rocket Lots Rockets Leakers Detected Found to BeLeakinga
PRO 294 330,000 203 0.06
PR-RS 5 15,000 96 0.64
RD-RS 10 14,000 77 0.55
RO-RS 9 10,000 476 4.80
aThese leaks were detected by periodic surveillance and were external to the rocket.
Source: U.S. Army (1985b).
Three GB rockets that had not been leakers previously
were found to have external leaks after being trans-
ported to the disposal facility. Two rockets were from
one PRO subtype lot and one was from an RD-RS lot.
The Army estimated with 95 percent confidence that
up to 1.8 percent of the rockets could develop leaks as
the result of handling and movement and concluded
that all rockets had the potential to become leakers
while in storage or as a result of movement (U.S. Army,
1985b).
The 1985 investigation found that GB agent purity
and its degradation by-products correlate with the his-
torical leaker rate and the degree and severity of corro-
sion found in metallurgical examinations. The authors
observed that there appears to be a correlation between
acid content and leakers (U.S. Army, 1985b). How-
ever, as shown in Table B-2, acidity levels for the PRO,
PR-RS, and RD-RS GB subtypes are similar, but the
percent of PRO-filled rockets that leaked is much
smaller than that of PR-RS or RD-RS filled rockets.
This suggests that some factor other than acidity is af-
fecting corrosion behavior.
Table B-3 identifies the distribution of GB rocket
lots by agent type. All the rockets containing the most
corrosive subtype of GB agent, RO-RS, have already
been destroyed. Extreme pitting depth and corrosion
were reported on metal parts from rockets containing
all four agent subtypes. Table B-4 reports the condition
of the warheads examined in this study. However, since
the samples were selected because they appeared to
have leaks, they were not representative of the condi-
tion of the overall stockpile of rockets when the study
was conducted. The Army stated that a better charac-
terization of the condition of the overall stockpile of
rockets at that time is given by Table B-5 (U.S. Army,
1985b).
Pitting in the aluminum rocket warheads was re-
ported to be worst at the agent liquid level line. Pitting
at this location, which is encountered quite frequently
in corrosion events, results from attack at the liquid/
vapor interface, which may be due to condensation of
moisture at the liquid surface. The extent of attack has
been correlated to the acidity of the agent.
Burster casing corrosion (pitting) was less severe
than that on the warhead body. This was attributed to
the fact that the burster casing is always below the agent
liquid level. Of the 43 burster casings examined, 31
had no pits, 9 had a few shallow pits (less than 30 per-
TABLE B-2 Acidity Levels for Various Types of GB-Filled M55 Rockets
Acidity Level 95 Percent Percent of Stockpile
Type of GB Agent (ma H+/100 g) Confidence Interval Found to Be Leaking
PRO 25.2 21.2to 29.2 0.06
PR-RS 29.2 15.6 to42.8 0.64
RD-RS 22.2 9.6 to 34.8 0.55
RO-RS 61.8 43.7 to 79.8 4.80
Source: Adapted from U.S. Army (1985b).
OCR for page 61
APPENDIX B
TABLE B-3
Agent Type
Distribution of GB Rocket Lots by Storage Location and GB
Number of Rocket Lots (number sampled)
Storage Location PRO PR-RS RD-RS RO-RS Total
Anniston 22~3) 5 (5) 0 0 27 (8)
JohnstonIslanda 45 0 0 0 45 (0)
Lexington-Blue Grass 34~3) 1 (1) 0 0 35 (4)
Pine Bluff 126 0 0 0 126 (0)
Tooelea 74 (6) 0 7 (7) 10 (10) 91 (23)
Umatilla 70~10) 1 (1) 1 (1) 0 72~12)
Total 371 (22) 7 (7) 8 (8) 10 (10) 396 (47)
aGB munitions at these locations have been destroyed.
Source: U.S. Army (1985b).
cent of the wall), 2 had pits with 30 to 50 percent pen-
etration, and 1 had severe pitting, with five of the pits
having greater than 65 percent penetration. The burster
. . . .
warn severe pining was found to be leaking.
There was a puzzling inverse relationship between
warhead corrosion and burster casing corrosion. War-
heads with severe corrosion had burster casings with
no corrosion. The two bursters with medium pit depths
(30 to 50 percent) came from warheads with little cor-
rosion. The leaking burster casing came from a war-
61
head that also had little corrosion. The one factor in
common was that the agent acidity associated with the
three burster casings with medium to severe pitting was
low, i.e., an average of 9 mg H+/100 g.
Gelled agent did not have a consistent effect on war-
head corrosion. Two samples had general corrosion
with no deep pits. This agent had no acidity. A third
warhead had severe pitting, with two pits exhibiting 58
to 71 percent penetration. Agent acidity from this war-
head was high, 65.3 mg H+/100 g.
TABLE B-4 Condition of M55 Rocket Warheads Examined: Average Number of Pits in the Warhead Sample
as a Function of Warhead Condition and Pit Depth
Percent of Wall Penetrated
Type of GB Warhead Sample
Agent Condition Size 0-14 15-41 42-57 58-71 72-100 Comment
PRO
PR-RS
RD-RS
RO-RS
Good
F.
alr
Poor
Good
Fair
Good
.
Falr
Poor
Good
Fair
Poor
11
2
s
2
2
4
2
2
1
3
1
3
2
62
1.5
s
0.5
o
28
1
o
12
6
50
39
43
0.1
4
56
o
2
o
o
8
1
o
o
1
40
10
25
o
1
1
o
o
o
o
0.5
o
o
o
o
s
3
s
o
o
o
o
o
o
o
o
o
o
o
o
1
2
2
o
o
o
o
o
0.25
o
o
o
o
o
o
Leaker
Burster tube leak
E.
ven corrosion
One leaker
Seal ball pitting
Gelled agent
Gelled agent
Known leakers
Source: U.S. Army (1985b).
OCR for page 62
62 EFFECTS OF DEGRADED AGENT AND MUNITIONS ANOMALIES ON CHEMICAL STOCKPILE DISPOSAL OPERATIONS
TABLE B-5 Results of Visual Inspection for Sampled M55 Rocket Warheads
No. of Samples No. of Pitted Percentage of 95 Percent
Type of GB Agent Examined Warheads Pitted Warheads Confidence Interval
PRO 44 4 9 3-22
PR-RS 14 4 29 8-58
RD-RS 20 7 35 15-59
RO-RS 16 9 56 30-80
Total 94 24 26 17-35
Source: U.S. Army (1985b).
M2A1 4.2-lNCH HD ROUNDS
In 1986, 4.2-inch HD rounds from Pueblo Army
Depot were studied (U.S. Army, 1986b). Both were
from the same box and had been stored in the vicinity
of four other rounds that were confirmed as heavy
leakers. One round had only the deterioration associ-
ated with storage. The second round had significant
deterioration on the forward end (including the fuze,
ogive, and body section). Analyses of deposits on this
round confirmed the presence of mustard agent. The
deterioration of this round was attributed to corrosion
from the mustard agent.
TON CONTAINERS
GB
Four brass valves on ton containers of GB were ex-
amined in a 1986 report (U.S. Army, 1986c): one that
had been at the bottom of a GB ton container, one that
had been at the top of a different GB ton container, and
two new valves. Three plugs that had been exposed to
GB in different ton containers also were examined. The
bottom valve had corroded in the threaded section from
the inside in a nonuniform fashion. The top valve and
plugs showed no visible dimensional change, but the
interior surfaces of the plugs were covered with a black
deposit. The brass (60 Cu/38 Zn/2 Pb) in both the
valves and plugs had undergone intergranular corro-
sion as well as selective attack of the beta (zinc-rich)
phase.
iThe alloy composition has a two-phase structure, alpha and
beta, with undissolved lead. The beta phase has a higher zinc con-
tent than the alpha phase. Intergranular corrosion occurs at the grain
Mustard Agent
Reaction of degraded HD with the iron in the steel
container produced hydrogen, which can build up to
high pressure in the headspace (U.S. Army, 2001~.
Pressures of 8 to 136 psig have been found in ton con-
tainers and up to 200 psig in projectiles. This hydrogen
presents two hazards. First, it could cause degraded
plugs to pop out of the container. Second, it could ig-
nite when the container is opened and an ignition source
is present. For this reason, workers will need special
training for such operations, and areas where such con-
tainers are opened will need electrical services and ven-
tilation systems designed for the possible presence of
hydrogen.
REFERENCES
ASM (American Society for Metals). 1961. Properties and Selection of
Metals, prepared under the direction of the Metals Handbook Commit-
tee. T. Lyman, ed. Metals Park, Ohio: American Society for Metals.
U.S. Army. 1966. M55 Rocket and Aluminum Bomblets. Aberdeen Prov-
ing Ground, Md.: Program Manager for Chemical Demilitarization.
U.S. Army. 1983. Metallurgical Investigation of 105-mm, GB, M360 Pro-
jectiles Stockpile. Aberdeen Proving Ground, Md.: Program Manager
for Chemical Demilitarization.
U.S. Army. 1984a. Summary of AMMRC Findings from 155 GB M121/A1
Projectile Metallurgical Investigation at Tooele Army Depot. Aberdeen
Proving Ground, Md.: Program Manager for Chemical Demilitarization.
U.S. Army. 1984b. Leaking 8-inch GB M426 Projectile Resulting from
Crack in Metal Parts (Update on Memorandum). Aberdeen Proving
Ground, Md.: Program Manager for Chemical Demilitarization.
(crystalline phase) boundaries, and the grains of the beta phase ap-
pear to have been more rapidly attacked than the grains of the alpha
phase (ASM, 1961; see pp. 1013-1038, especially p. 1024~.
OCR for page 63
APPENDIX B
U.S. Army. 1985a. Minutes Ongoing Metallurgical Examination of Leak-
ing Toxic Chemical Items, January 8-9, 1985, Conducted at AMMRC.
Aberdeen Proving Ground, Md.: Program Manager for Chemical De-
militarization.
U.S. Army. 1985b. Independent Evaluation/Assessment of Rocket, 115-
mm: Chemical Agent (GB or VX), M55. Aberdeen Proving Ground,
Md.: Program Manager for Chemical Demilitarization.
U.S. Army. 1986a. Metallurgical Analysis of Leaking MC-1, GB and MK-
94 Mod O. GB Bombs. Aberdeen Proving Ground, Md.: Program Man-
ager for Chemical Demilitarization.
63
U.S. Army. 1986b. Cartridge, HD 4.2 Inch: Gas, M2A1 Postmortem Inves-
tigation Leakers (Case 4-PUDA-78). Aberdeen Proving Ground, Md.:
Program Manager for Chemical Demilitarization.
U.S. Army. 1986c. Ton Containers, Progress Reports. Aberdeen Proving
Ground, Md.: Program Manager for Chemical Demilitarization.
U.S. Army. 2001. Stockpile Tracking System Lot Book. Final Revision 2.
Aberdeen Proving Ground, Md.: Program Manager for Chemical De-
militarization.
Representative terms from entire chapter:
ton containers
