Confined Space Case study 2012 - UW Courses Web Server
Transcript of Confined Space Case study 2012 - UW Courses Web Server
United Airlines Fatality
Case Study � UAL IL (Will & Tim) crew is called to repair a seal leak in a dry bay at Dulles
airport, and train VA crew. � Prior to arrival, fuel is removed from wet and dry bay and fuel cell was
venFlated � Atmosphere is measured for explosive levels � IL crew requests compressed air (from VA crew) to determine where the leak is
located � Will enters dry bay and VA member enters wet bay and quickly idenFfied leak
locaFons � Both crews go to break
Case Study � Upon return, area is prepared for
repair work � Will is “tank watch” while VA crew
enters wet bay to begin repair work � Tim works with VA crew on dry bay � Direct read for explosives is placed
in dry bay and VA crew goes to get gas for heater to cure seal
� Tim enters dry bay with half mask organic vapor respirator, MEK and vacuum and begins scrapping seal
� Hand vacuum is powered with compressed air to clean up seal
Case Study � Will hears silence in dry bay 2
minutes aRer Tim enters the space
� Will looks in dry bay and is immediately overcome and passes out
� 911 is called and mulFple aUempts are made to remove the body
� Air monitor is found on floor and atmosphere is test
� ARer 1 hour of rescue aUempts, five mechanics removed the body
WHAT WENT WRONG?
Root Causes � All UAL mechanics were trained to enter the fuel cell
� Regardless of frequency they performed the work � Monitoring VOC levels by measuring flammable levels
� At lower levels a meaningful conversion cannot be made � Did not measure O2, and air contaminant levels � Tim had no aUendant
� UAL policy was one aUendant per space � Was not in contact with anyone while in the space, and Will was not noFfied he had entered
� Minimal plan for rescue � No usable supplied air � Unsure of points of entry � Unsure of atmospheric condiFon
� Mechanic entered space mulFple Fmes � Not trained rescuers � Lacked proper equipment � Lacked understanding of hazards upon entering for rescue
� Hand vacuum was powered with N2, not compressed air � Vacuum exhausts air at handle � Dry bay was quickly flooded with N2, displacing the O2
CorrecFve AcFons � Limit who could perform fuel cell work
� Only two staFons � Only specific crews � Consistent training for all performing the work
� Purchase PIDs � Use prior to and during entry to monitor flammability, O2, and air contaminant levels
� Use supplied air respirators � Treat fuel cells as permit required confined spaces � Align wriUen program with OSHA
� Used OSHA language-‐i.e. confined space, aUendant etc � Use Push/Pull venFlaFon system
� Defined locaFons for venFlaFon � More effecFve method of venFlaFng space
� Best pracFce procedures developed by NaFonal Safety Council for fuel cell entry: Safety Handbook AviaFon Ground OperaFons
Best PracFce Controls • Best pracFce controls for confined space entry can be found in ANSI Z117.1-‐2009, Safety
Handbook AviaFon Ground OperaFons and through NIOSH. Hazards to consider: • Physical:
– Head strikes, cuts and laceraFons – Eye protecFon
• Goggles for overhead work or splash potenFal – Electrical and igniFon sources
• All electrical equipment (lights and tools) cerFfied for hazardous environment • StaFc discharge must be controlled-‐clothing, vent ducts, plasFc bags and rags • Prohibit food, drinks, metal clothing, jewelry and electronics
– Working at heights – Noise exposure
• Ensure hearing protecFon does not prevent communicaFon with aUendant – Heat exposure caused by space, clothing or work – Engulfment/Drowning
• Blind, disconnect, remove or double block and bleed
Best PracFce Controls � Ergonomic:
� Restricted entrance/exit or workspace � RepeFFve moFon-‐especially in rework � Tool vibraFons � Task lighFng
� Atmospheric: � RepresentaFve test of space
� Test space a mulFple levels � InhalaFon Hazard
� TLVs of the chemicals being used � Account for surrounding work with chemicals or vehicles
� CombusFbility of atmospheric � Account for surrounding acFviFes
� Oxygen Deficiency � Inert gas such as N2 and Ar should only be used with special procedures � Oxygen enrichment should never be used
Best PracFce Controls � Emergency Response Plan
� Consider response Fme and available equipment: � SCBAs or supplied, fire exFnguishing equipment, tools to cut the space and life
supporFng/first aid equipment. � Responders must be physically capable of entering the space. � Familiarize rescuers with restricFons of the space and physical and atmospheric
hazards and pracFce rescue entry � Simulate actual rescue condiFons
� CommunicaFon: � AUendants and entrants must be capable of constant communicaFon
� Tapping or pulling on lifelines/air hoses-‐limitaFons in the amount of informaFon portrayed
� Electronic communicaFon through two-‐way radios or hard-‐wired intercoms equipped for tone, flasher or vibrate alert-‐ voice capability is desirable.
� If an electronic system is used it must be cerFfied for use in a flammable/combusFble environment.
� Test equipment � Bump test direct read instruments prior to use � Test venFlaFon and supplied air for effecFveness