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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

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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.

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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).

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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).

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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~.

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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.