Confined Space Entry. Objectives This is intended an overview of the confined space hazards and...
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Transcript of Confined Space Entry. Objectives This is intended an overview of the confined space hazards and...
Confined Space Entry
Objectives
This is intended an overview of the confined space hazards and control
Students should: Understand the extent of the problem Know applicable definitions Recognize the hazards of confined spaces Be familiar with methods to control these hazards Know basic OSHA requirements for confined
space entry
Confined Space: Definition
A Confined Space means a space that:Is large enough and so configured that an employee can bodily enter and perform assigned work ; andHas a limited or restricted means for entry or exit (For example: tanks, vessels, silos, pits, vaults,hoppers);and,Is not designed for continuous employee occupancy.
Permit Required Confined Space: Definition
A Permit Required Confined Space means a confined space that has one or more of the following characteristics:
Contains or has a potential to contain a hazardous atmosphere,
Contains a material that has the potential for engulfing an entrant,
Permit Required Confined Space: Definition (cont’d)
A Permit Required Confined Space means a confined space that has one or more of the following characteristics:Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section. Contains any other serious safety or health hazard.
Confined Space Risk
Confined spaces are deadly. OSHA data (annual)
63 fatalities 5000 serious injuries Up to 60% of victims are would-be rescuers
NIOSH documents: Preventing Occupational Fatalities in Confined Spaces Preventing Entrapment and Suffocation Caused by the Unst
able Surfaces of Stored Grain and Other Materials (1987) Preventing Deaths of Farm Workers in Manure Pits Preventing Occupational Fatalities in Confined Spaces
Confined Space RiskUtah has many recent fatalities: Two welders died inside a pipe from argon asphyxiation,
1997 An employee died after being buried with salt while
cleaning a bin, 1995 Two maintenance workers (one was a "rescuer") died from
nitrogen asphyxiation while working in an oil-refinery tank, 1995
Two relatives (uncle and nephew) died inside an asphalt truck tank, 2000
A central Utah dairy worker was asphyxiated when he fell into a manure pit, 1998
A truck driver died when he went into a storage tank
Causes of Death (NIOSH)
Atmospheric hazards - 56% of fatalities
Engulfment (34% of fatalities)
Causes of Death (NIOSH)
Oxygen-deficient atmospheres
Oxygen is consumedGases displace oxygen
Combustible atmospheres
Flammable gas, vapor or dustOxygen enriched Combustible concentrations are far above safe toxic exposure
Toxic atmospheres
Product stored in the spaceActivity in the confined spaceSources outside the confined space
Engulfment
BridgingSlumpingHang-upRat hole
Safety and Physical hazards
Temperature extremesConverging walls or floorsMechanical hazardsElectrical hazardsNoise?Falls - slick/wet surfacesFalling objects
Initial Atmospheric testing
Oxygen Oxygen meters
Electro-chemical detectors Instrument displays %
Oxygen Minimum 19.5% O2
(OSHA limit)Test oxygen first
Initial Atmospheric testing
Combustible gases and vapors Combustible gas meters,
“Heat of combustion" meters Combustible gas meters need oxygen to work Instrument displays Percent Lower Explosive Limit (LEL) (OSHA uses the term Lower Flammable, LFL)
No more than 10% LFL (OSHA)Combustible dusts No more than LFL (OSHA) LFL at approx. 5 foot visibility
Initial Atmospheric testing
Toxic gases and vapors Toxic gas meters Electrochemical detectors Detector tubes, etc.
No more than PEL (TLV, etc.)Toxic agent may cause injury or impair escape (OSHA)
Additional atmospheric testing
After ventilating the spaceUpon first entryContinual monitoring if conditions could change Personal alarms (for entrants) Periodic re-testing
Instruments for confined spaces
Combination instruments commonly used Multi-gas, LEL, Oxygen
Instruments must be properly calibratedUsers must be trained
Ventilation
Inerting Inert gas displaces oxygen (to control flammable
hazard) IDLH hazard!
Natural ventilation Wind Convection
Ventilation
Mechanical Ventilation Compressed air May be suitable for small spaces Venturi blowers make more efficient use of compressed air
Ventilation
Air mover at openingPortable ventilation system
Ventilation
Ventilation strategies Supply mode Exhaust Mode Simultaneous supply and exhaust Displacement ventilation
Removes hazard before entry Minimum 10 air changes (AC)
Dilution ventilation reduces hazard during entry
VentilationRecommended air changes
Contaminant reduction
Conditions
10 10 - 100x good mixing and negligible contaminant release
20-30 10 - 100x poor mixing or significant contaminant release
30 - 60 10 - 100x poor mixing and significant contaminant release
60 - 100 (ventilation alone may not be adequate)
Negligible air movement and high contaminant release
BAdapted from McManus, Safety and Health in Confined Spaces,1999
Isolation
Tag and lock out circuits and linesDisconnect drives and linkagesSecure moving parts
Isolation
Blank and bleed lines "Blind" flanges "Double Block and
Bleed "
Ignition, electrical
Ignition control Non-sparking tools Classified electrical equipment ("Explosion proof")
Electrical control Grounding Ground Fault Circuit Interrupters Isolating transformers
Personal protective equipment
Atmosphere supplying respirators
Personal protective equipment
Air purifying respirators Protective clothing
Retrieval devices
Retrieval systems Safety belt/harness, lanyards,
winch Required for top entry (OSHA)
Prepare for rescue before entry
Standby/Rescue
CommunicationsNever enter confined spaces alone! Outside monitor at all times Continuous communication with entrants
Rescue Rescue team on standby Monitor summons help Never attempt an unplanned confined space
rescue!
Confined Space Programs
Identify confined space hazards Find and
evaluate spaces Labels, signs
Confined Space Programs
Confined Space Entry Permit Test space before entry Specify precautions and conditions and duration of
permit Sign permit and post on site Permit cancelled at end of job or if conditions
change
OSHA, General Industry
1910.146, Permit required confined space Scope and application(1910.146(a) Definitions(1910.146(b)
Confined Space: Large enough to enter Limited entry or exit Not designed for continuous occupancy
Permit required confined space.-a confined space with: Hazardous atmosphere potential Potential for engulfment Inwardly converging walls Any other recognized safety hazard
OSHA, General Industry
General requirements(1910.146(c) Evaluate workplace Post signs Keep employees from entering,
-or- Establish entry program Alternate procedures for spaces where ventilation alone is
adequate to control hazard Re-evaluate as necessary Re-classify spaces as necessary Employer coordinates with contractors Contractors coordinate with employer
OSHA, General Industry
OSHA Permit-required confined space program, 1910.146(d) Prevent unauthorized entry Identify and evaluate before entry Develop means and procedures for safe entry Provide equipment, training Evaluate permit space conditions
Employee observation Inform employees of result
OSHA, General Industry
OSHA Permit-required confined space program, 1910.146(d), continued Provide outside attendant Provisions for multiple spaces (single attendant) Designate persons and roles Rescue and emergency procedures System for entry permits Procedures for contractors Procedures to conclude the entry Review to correct deficiencies Review and revise the program
OSHA, General Industry
Permit system, 1910.146(e) Procedures before entry Permit must be signed Permit available to entrants Duration specified Canceling the entry Retained for at least l year
OSHA, General Industry
Requirements for the entry permit, 1910.146(f)
Space Purpose Date and Duration Personnel Supervisor Hazards Control measures Acceptable entry conditions Test results Rescue provisions Required equipment Other information
OSHA, General Industry
Training, 1910.146(g) Provide all training needed When to provide training Establish employee proficiency Certify training accomplished Duties of entrants, 1910.146(h) Duties of attendants, 1910.146(i) Duties of supervisors, 1910.146(j) Rescue, 1910.146(k)
OSHA, General Industry
Appendix A - Flow ChartAppendix B - Procedures for Atmospheric testingAppendix C - Examples of Confined Space ProgramsAppendix D - Sample PermitsAppendix E - Sewer System Entry