Vandenberg AFB Launch Equipment Room Electronic Drawer Corrosion Control Program VALEDCCP

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Vandenberg AFB Launch Equipment Room Electronic
Drawer Corrosion Control Program(VALEDCCP)

• KyAnn Myers
• Program Manager
• ICBM System Program Office
• Ogden ALC, Hill AFB, Utah

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Program History

• Hill AFB was tasked by AF Space Command to find a
  solution to Vandenberg AFB electronic drawer
  corrosion problem
• Electronic drawers at VAFB are experiencing a
  significant amount of corrosion
• These drawers are used in Intercontinental
  Ballistic Missile (ICBM) test launch operations
  at VAFB
• VAFB launch silos are extremely close to the
  Pacific Ocean and are exposed to the corrosive
  effects of sea spray, ocean salt, fog, and sand
• These drawers pass electrical checkouts, but fail
  visual corrosion inspection criteria in the
  Technical Order (TO)
• TO requires no visible corrosion, but waivers to
  use corroded drawers are routinely being
  processed

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VALEDCCP Program Elements

• Program is designed to execute in three elements
• Element One Corrosion control enhancements to
  VAFB Minuteman Launch Facilities
• Element Two Procedural changes for drawer
  handling post launch
• Element Three Cleaning, repair, and conformal
  coating procedures for drawers that fail
  electrical checkout

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Element One Corrosion Control

• ELEMENT ONE - Designed to slow corrosion by
• Reducing humidity with a Dehumidifier
• Filtering out corrosive gases and contaminants
  from launch gases and refurbishment activities
  with a Gas Phased Filter Cabinet
• Preventing debris (salt, sand, etc.) from
  entering the area in the missile silo where the
  electronic drawers are used with Environmental
  Curtains and Covers

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Dehumidifier

• Commercial grade dehumidifier successfully
  installed and validated/verified.
• Estimate that in a worst case scenario (open
  hole, no barriers) dehumidifier will remove 3.5
  gallons in a 24-hour period.
• Dehumidifier maintains area at 40 relative
  humidity. MIL-HDBK-1250 (18 Aug 95) 5.2 The
  moisture level inside electronic equipment shall
  be maintained below 45 percent relative
  humidity.

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Gas Phase Filter Cabinet (GPFC)

• The GPFC utilizes four filters a pre-filter, a
  post-filter, and two chemical filter cells.
• The lower chemical filter cell consists of two
  modules containing activated carbon impregnated
  with potassium hydroxide (KOH). (High pH)
• The upper chemical filter cell contains a
  mixture of 75 virgin carbon and 25 activated
  carbon impregnated with citric acid. (Low pH)

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Environmental Curtains

• Environmental curtains were installed over the
  diving board and launch tube access
• The curtains are overlapping 8-inch strips of
  plastic designed to protect the drawers from
  moisture and debris
• Very effective on 8/30/02 humidity was 74 out
  in the launch tube and 40 in the area where the
  electronics are used

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Miscellaneous Covers

• Additional covers also over collimator slot,
  PAH floor plate, and others.

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Accomplishments

• Humidity verified at sustained 40 relative
  humidity in Launch Equipment Room
• Verified gas filter performance through refurb
  activities where corrosive gases/contaminants
  were introduced
• Corrosion coupon differential between inlet and
  outlet
• Chemical analysis of filter media verified pH
  move to neutral (indicates removal of corrosive
  gases)
• Tests verify environmental curtains isolate
  dehumidified environment during open missile silo
  activities

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Element Two Procedure Changes

• ELEMENT TWO - Designed to prevent further
  corrosion by implementing the following drawer
  handling procedural changes
• Drawers will be packaged in dehumidified silo
  following launch for shipment to Electronics Lab,
  to prevent activation of contaminants
• Drawers will be inspected, wiped with alcohol,
  and vacuumed within 48 hours of a launch to
  remove debris
• After Electronic Lab vacuuming, drawers will be
  packaged for storage in single use plastic bags
  impregnated with a corrosion inhibitor
• Procedure will be added for cleaning air passages
  and ducts in the Minuteman missile silos

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Element Two Needs

• Looking for equipment and procedures to clean
  debris from ducts in missile silos in an EPA
  approved manner
• Tentatively identified a single use plastic bag
  impregnated with a corrosion inhibitor, but still
  determining if a better/less expensive bag exists
• (Not a solicitation for bid)

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Element Three Corrosion Cleaning

• ELEMENT THREE - Designed to clean, repair, and
  conformal coat corroded assets that have failed
  without further damage to the ELECTRONIC
  components
• These cleaning processes are not for aesthetics
• Cleaning will NOT be performed on drawers that
  have visible corrosion, but pass an electronic
  functionality test
• All conformal coating and cleaning will be done
  with approved chemicals and procedures

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AF Research Lab Position

• Removing the corrosion because it looks bad (i.e.
  fails a visual inspection) will damage the
  drawers and cause more failures to occur
• AFRL Recommendation (From letter to AFSPC dated
  15 Jan 02)
• Cleaning should not be performed for only
  aesthetic reasons. If the components in the
  drawers have not experienced operational
  failures, cleaning may result in more damage than
  leaving components alone
• Example Cleaning corrosion from wire wrap pins
  may cause gaps in connections between the wire
  and the pin and thus lead to failure of the
  drawer

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Element Three Needs

• Looking for equipment and procedures to clean
  corrosion from ELECTRONIC components
• Looking for approved conformal coating product
  for aged electronic equipment that considers
  potential heat load increase
• Looking for vacuum bake out oven to dry
  components thoroughly
• Tentatively identified some of this, but looking
  for better/cheaper ways
• (Not a solicitation for bid)

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Program Outcomes

• Corrosion that is currently present on drawers
  can not be safely removed. What we can do is
• Retard additional corrosion
• Reduce humidity, harmful launch
  gases/contaminants, and debris
• Develop handling procedures
• Develop non-invasive, electronic-safe cleaning
  and conformal coating procedures
• Mitigate the effects of corroded drawers
• Educate users on reducing corrosion and using
  corroded assets correctly
• Best utilize corroded assets to support the ICBM
  weapons system to 2020

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Discussion Questions
Keeping the Crosshairs on the Target
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Items from AFRL Letter to AFSPC

• Cleaning should not be performed for only
  aesthetic reasons. If the components in the
  drawers have not experienced operational
  failures, cleaning may result in more damage than
  leaving components alone
• Recommendations
• Request waiver to cosmetic appearance
  requirements that are now driving the cleaning of
  fully functional equipment. Clean only those
  assemblies exhibiting failures induced by the
  presence of corrosion products
• Initial screening tests should be performed at
  the board level to isolate problems, rather than
  performing cleaning process on all the components
  in the drawer
• Any corrosion preventative compound proposed for
  use should be tested on conformal coatings used
  on these components to ensure degradation does
  not occur

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Recommended Cleaning Process Highlights

• Spot clean to remove corrosion in failed areas
  and prepare other specified areas (Option 3) for
  conformal coating.
• Remove corrosion by scrubbing with ethyl alcohol.
• Remove corrosion on ferrous and gold-plated
  surfaces by scrubbing with ammonium hydroxide.
• Avoid contact with aluminum (chassis), copper
  (wires), silver or lead surfaces.
• Avoid areas where ammonium hydroxide may become
  entrapped.
• Wire wraps must be removed before cleaning
  gold-plated pins.
• Surface preparation for conformal coating
• Remove any surface contaminants introduced by
  wiping with isopropyl alcohol
• Remove all remaining water and alcohol by
  thoroughly blow drying with compressed air and
  using bake out oven
• Conformal coating application
• Mask areas not to be conformal coated
• Apply Humiseal P/N 1B15H (NSN 5970-00-990-4924)
• Allow to cure and check under UV light for
  coating uniformity and missed (uncoated) areas