CAD/PAD Propellant Stability Program

Transcription

1 CAD/PAD Propellant Stability Program Emily Vandevender and Justin Gamble E22 Ordnance Assessment May 23, 2017 FINAL. Distribution Statement A: Approved for Public Release; distribution unlimited Images herein are credited to NSWC IHEODTD.

2 Customer/Deliverables Sponsor: Naval Air Systems Command (PMA 201) Customer Advocate: Joint Program Office (JPO) End User: Naval Air Systems Command (PMA 201), USN/MC Requirements: Bulk IMHR End-items OPNAVINST C & C Deliverable: bulk historical data records; one analysis per each Ordnance Assessment report for end items 2

3 Overview What We Do and Background Types of Nitrate Ester Propellant Result of Nitrate Ester Decomposition Stabilizers and Effective Stabilizer Safety Criteria Test Methods Bulk Sample Selection and M6 Incident End-item Sample Selection and XW50 Incident Future Questions 3

4 What We Do Monitor the stability of CAD/PAD government-furnished material (GFM) propellants Conduct testing to ensure the safety of propellant Bulk and loaded (end-items) Alert users of unsafe conditions Forecast chemical shelf-life 4

5 Stability Testing Background Two propellant stability test programs at Naval Surface Warfare Center Indian Head Explosive Ordnance Disposal Technology Division Bulk propellant and loaded propellant (end items) Bulk stability test program has been ongoing since late 1970s Currently monitoring 20 bulk formulations, 37 granulations End-item testing originated in 1996 Currently monitoring 50 end-items 5

6 Propellant Configurations GFM Propellants (Bulk configuration) End Items (Loaded configuration) 6

7 Types of Propellant Three main categories of propellants that contain nitrate esters Single-base: nitrocellulose (NC) Double-base: nitrocellulose and nitroglycerin (NG) Triple-base: nitrocellulose, nitroglycerin, and nitroguanadine (NQ) Stability testing is conducted on single-base and double-base propellant NQ less sensitive to thermal stimuli Nitrate ester 7

8 Stabilizers Prevent Decomposition Incorporating stabilizers into the propellant mix slows down decomposition of propellant, but does not completely prevent it As the propellant ages, the capacity of the stabilizer to prevent decomposition is reduced, and the stabilizer concentration is depleted Rapid depletion indicates propellant that is potentially becoming unstable Three main stabilizers: Diphenylamine (DPA) 2-nitrodiphenylamine (2NDPA) Ethyl centralite (EC) 8

9 Result of Nitrate Ester Decomposition Bulk Propellant Loaded Propellant Building 518 fire at NSWCIHDIV (August 1994) FA-18 PDRM auto-ignition at NAS China Lake (July 2007) 9

10 Effective Stabilizer Stability testing determines how much of the stabilizer remains in the propellant To quantify amount of stabilizer, the Effective Stabilizer (ES) concentration is calculated Aggregate concentration of effective stabilizer compounds in the propellant Expressed as a weight percent in terms of virgin (primary) stabilizer Takes into account stabilizer daughter products that form and also help stabilize propellant 10

11 Propellant Stability Safety Criteria Minimum safe stabilizer levels are 0.10% virgin stabilizer or 0.20% effective stabilizer (ES) ES is determined based on the contribution of the derivatives of the virgin stabilizer Maximum acceptable stabilizer depletion rate is 10% per year Rapidly depleting propellant is disposed of even if stabilizer levels are within safe limits 11

12 Test Methods: Visual Inspection Visual Inspections conducted during sampling operations to check for discoloration and deformation PDRM propellant grain: KU and Mechanite 19 Color change shows depleting virgin stabilizer (2NDPA) and effective stabilizer (2NDPA + Daughter Products) 1.49% ES 0.95% ES 0.0% ES 12

13 Test Methods: HPLC High Performance Liquid Chromatography (HPLC) used to measure the concentration of the stabilizer and daughter products which are used to calculate the effective stabilizer Stabilizer is extracted from propellant to prepare test samples HPLC Instrument 13

14 Sample Selection: Bulk Propellant Ammunition Distribution and Control (AD&C) reviews propellant in the Ordnance Information System (OIS) monthly and provides identification information of propellant that need tested Bulk propellants are tested on a 2 or 3 year cycle, depending on the stabilizer Bulk Propellant Grains 14

15 M6 Propellant Stabilizer Depletion September 2014: Routine Bulk Propellant testing on M6 propellant Lot HIK95L M6 Bulk Propellant Lot HIK95L Stability Results Stabalizer Percentage (%) %DPA 0.60 %ES 0.40 DPA Spec ES Spec Age (Months) 15

16 M6 Mitigation Plan Bulk M6 propellant All drums placed in condition code H via Notification of Ammunition Reclassification (NAR) Condition code H: segregation and immediate disposal Loaded M6 Propellant M510 cartridges pulled from stock and emergency downloaded and tested Stability analysis showed concentration below minimum specification for virgin stabilizer; above minimum specification for ES All remaining M510 stock sent for immediate disposal due to low stabilizer; NAR drafted for all remaining M510 cartridges in stock 16

17 Sample Selection: End Item The Ordnance Assessment (OA) program determines when loaded propellants are tested End items on the OA schedule are tested on 3 to 5 year cycle Special safety tests and assessments are performed on items that tested low or failed stabilizer tests during an OA XW50 Impulse Cartridges 17

18 Downloading End-Items Downloading is the process of removing loaded propellant from an end-item Item is usually cut (dissected) X-rays and sectional/top assembly drawings used to determine location of cut Remote cutting process to ensure safety of personnel: Diamond Wire Saw Millennium Diamond Wire Saw 18

19 XW50 Investigation XW50 impulse cartridges contain the same propellant as the PDRM Different location on the ejection seat PDRM higher on the back of the seat XW50 lower on the back of the seat Different cartridge exteriors PDRM has a black exterior XW50 has a shiny silver exterior Stability testing was performed to ensure stabilizer levels were within safety criteria 19

20 Stabilizer Thresholds for Fleet-Returned XW50s Two different propellant shapes per XW50 slug and disk Stability testing showed that virgin stabilizer was below specification, but ES was above specification XW50 cartridges were placed in a monitor status, no service life change % VIRGIN STABILIZER KU Slug Virgin Stabilizer KU Disk Virgin Stabilizer % EFFECTIVE STABILIZER KU Slug Effective Stabilizer KU Disk Effective Stabilizer Installed Time (Months) Installed Time (Months) 20

21 Future Endeavors Bulk propellant and End-Item stability data will be incorporated into the Virtual Fleet Support (VFS) database Exploring new methods of monitoring stabilizer depletion such as micro-chips or microelectromechanical systems (MEMS) in rocket motors or PADs Continued testing of hot climate fleet-returned assets 21

22 QUESTIONS? 22

23 Contact Information CAD/PAD