grain handling safety osha - 29 cfr 1910.272
TRANSCRIPT
Paul SchlumperGeorgia Tech Research Institute404-407-6797
Oxygen
Confinement
IgnitionFuel
Dispersion
Dust Explosion Requirements
Adapted from CSB
Some event disturbs the settled dust into a cloud
Dust cloud is ignited and explodes
Dust explosion in a work area
Dust settles on flat surfaces
Dust
Adapted from CSB
Dust explosionsDust explosions
An initial (primary) explosion in• processing equipment or in an area
where fugitive dust has accumulated • may shake loose more accumulated dust, or• damage a containment system (such as a
duct, vessel, or collector). • The additional dust dispersed into the air may
cause one or more secondary explosions.
• These can be far more destructive than a primary explosion
Particles and PowdersParticles and Powders
Size• Pellets > 2mm
diameter • Granules 0.42mm and
2mm, and • dust particles < 0.42mm
(420μm)Hazard increases as particle size
decreases • larger surface area for combustion • Fine particle may have a larger role in
dust cloud ignition and explosion propagation.
Facility Analysis ComponentsFacility Analysis Components
Carefully identify:• Materials that can be
combustible when finely divided; • Processes which use, consume,
or produce combustible dusts;• Open areas where combustible
dusts may build up; • Hidden areas where combustible
dusts may accumulate;• Means by which dust may be
dispersed in the air; and • Potential ignition sources.
Facility Analysis ComponentsFacility Analysis Components
Identify and follow the applicable federal, state, and local laws and regulations. Some commonly applicable mandatory requirements
• OSHA General Duty Clause and Standards
• The International Code Council’s International Fire Code®
• NFPA’s Uniform Fire Code®.
29 CFR 1910
– Local building codes frequently adopt NFPA dust standards by reference
See Explosives
regulations
Dust CombustibilityDust Combustibility
The primary factor in an assessment of these hazards is whether the dust is in fact combustible.
*Determine if a dust cloud will:• Detonate• Deflagrate• Present a fire hazard• Or will Not burn or ignite
Testing may be necessary
Dust CombustibilityDust Combustibility
Combustible dust per NFPA 654• Prior to 2006 - “Any finely divided solid material that is 420 microns
or smaller in diameter (material passing a U.S. No. 40 Standard Sieve) and presents a fire or explosion hazard when dispersed and ignited in air.”
• *2006 Edition – A combustible particulate solid that presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations, regardless of particle size or shape.
Agricultural Dust per NFPA 61• Any finely divided solid agricultural material 420 microns or smaller
in diameter that presents a fire or explosion hazard when dispersed and ignited in air.”
*25 watt light bulb probably can not be seen through ten feet of a combustible dust mixture
Dust CombustibilityDust Combustibility
What bulb?
25 watts
2 meters
Glass Glass
40 g/m3 concentration of comb. dust suspended in air
What is wrong here?
Electrical classificationElectrical classification
• OSHA Electrical standard (29 CFR Part 1910 Subpart S)
• NFPA 70, the National Electrical Code®.
• NFPA 499, . . . Classification of Combustible Dusts and of Hazardous (classified) Locations for Electrical Installations in Chemical Process Areas.
ElectricalEquipmentClass IIDivision 1Division 2Group E
F G
CPL 03-00-008 – National Emphasis CPL 03-00-008 – National Emphasis ProgramProgram
“immediate cleaning is warranted whenever a dust layer of 1/32-inch thickness accumulates over a surface area of at least 5% of the floor area of the facility or any given room.”
NOTE: 1910.272 stipulates 1/8 inch for Grain Dust
Dust ControlDust Control
NFPA 654 - contains comprehensive guidance
Some of its recommendations:
Minimize the escape of dust from process equipment or ventilation systems;
Use dust collection systems and filters;
Utilize surfaces that minimize dust accumulation and facilitate cleaning;
Spots are not raindrops
?
Dust ControlDust Control
NFPA 654 – guidance
• Provide access to all hidden areas to permit inspection;
• Inspect for dust residues in open and hidden areas, at regular intervals;
• Clean dust residues at regular intervals;
Dust ControlDust Control
NFPA 654 – guidance• Use cleaning methods
that do not generate dust clouds, if ignition sources are present;
• Only use vacuum cleaners approved for dust collection;
HAZ LOC
Classified ElectricalClassified Electrical
Ignition ControlIgnition Control
NFPA 654, identifies comprehensive guidance
• Use appropriate electrical equipment and wiring methods;
• Control static electricity, including bonding of equipment to ground;
• Control smoking, open flames, sparks;
No!
Yes!
Ignition ControlIgnition Control
NFPA 654 - guidance • Control mechanical sparks
and friction;• Use separator devices to
remove foreign materials capable of igniting combustibles from process materials;
• Separate heated surfaces from dusts;
Magnetic Core
Non - Magnetic rotating drum
Ignition ControlIgnition Control
NFPA 654 - guidance • Separate heating
systems from dusts;• Proper use and type
of industrial trucks;• Proper use of
cartridge activated tools; and
• Adequately maintain equipment.
Hot work permit____________________________________
Grinder
Kaboom!
Ignition ControlIgnition Control
Other ignition sources
Use appropriate Class II Electrical equipment and wiring methods where required
OSHA 29 CFR 1910.178 (c) regulates powered industrial trucks in dust areas
Coal handling operations must comply with OSHA 29 CFR 1910.269
Class I & IIGroup D & G
Hazardous vertical surface accumulation
Employees need to be trained
• To recognize and prevent hazards associated with combustible dust
• In taking preventative action, and/or
• How to alert management.
TrainingTraining
Training Training
Management Responsibility• Comply with the Hazard Communication Standard• Have a qualified team conduct a facility analysis (or
have one done by qualified outside persons) prior to the introduction of a hazard and
• Develop a prevention and protection scheme tailored to the operation.
List of Chemicals
NFPA Standards – Dust HazardsNFPA Standards – Dust Hazards
61 Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities68 Deflagration Venting Systems69 Explosion Prevention Systems70 National Electric Code77 Static Electricity85 Boiler and CombustionSystems86 Ovens and Furnaces91 Exhaust Systems
NFPA StandardsNFPA StandardsElectrical & SystemsElectrical & Systems
484 Combustible MetalsIncludes Magnesium, Titanium, Zirconium, Aluminum, Tantalum and other reactive metals
499 Classification of Combustible Dust654 manufacturing, Processing and Handling of Combustible Particulate Solids655 Sulfur664 Woodand more
1910.272 – Grain Handling Facilities1910.272 – Grain Handling Facilities(Promulgated in March 1988)(Promulgated in March 1988)
• (a) – Scope• (b) – Application• (c) – Definitions• (d) – Emergency Action
Plan• (e) – Training• (f) – Hot Work Permit• (g) – Entry Into Grain
Storage Structures• (h) – Entry Into Flat
Storage Structures
• (i) – Contractors• (j) – Housekeeping• (k) – Grate Openings• (l) – Filter Collectors• (m) – Preventive
Maintenance• (n) - Grain Stream
Processing Equipment• (o) – Emergency Escape• (p) – Continuous-Flow Bulk
Raw Grain Dryers• (q) – Inside Bucket
Elevators
Application of StandardApplication of Standard
Sections (a) – (n) Apply to all grain handling
operations, such as elevators, mills, etc.
Sections (o) – (q) Apply to grain elevator
operations only.
Hot Work PermitHot Work Permit
• Hot Work Permits• Written• Authorized by Employer’s Representative• Meet requirements of 1910.252(a)• Kept on file until completion of operations
• Exceptions• Authorizing agent is present• Authorized welding shop• Authorized hot work area – outside of grain facility
Contractor InformationContractor Information
• Fire Hazards
• Explosion Hazards
• Safety Rules of the Facility
• Emergency Action Plan
HousekeepingHousekeeping
• Housekeeping Program• Written• Establish Frequency and Methods to Reduce
Accumulations:• Ledges• Floors• Equipment• Other Exposed Surfaces
• Priority Housekeeping Areas, including at least the following:
• Floor areas within 35 feet (10.7 m) of inside bucket elevators;• Floors of enclosed areas containing grinding equipment; • Floors of enclosed areas containing grain dryers located inside the
facility. • Important: Fugitive grain dust accumulations exceeding 1/8 inch
shall be removed immediately from priority housekeeping areas.
HousekeepingHousekeeping
Housekeeping Housekeeping
•Compressed Air can be used for cleaning IF:• Machinery in area shut-down• All other potential ignition sources shut-down and/or removed.
HousekeepingHousekeeping
HousekeepingHousekeeping
Dust Collection SystemsDust Collection Systems
• Fabric Dust Filter Collectors• Pressure drop monitoring device• Located outside of facility, OR• Protected by an Explosion Suppression System, OR• Protected by Fire-Resistant Construction
Preventive MaintenancePreventive Maintenance
• Equipment:• Dryers• Grain Stream Processing Equip.• Dust Collection Equipment• Bucket Elevators
• Preventative Maintenance• Regularly scheduled inspections
• Mechanical• Safety Control Equipment• 1910.272(m)(1) The employer shall implement preventive maintenance
procedures consisting of: • Lubrication and other appropriate maintenance• Prompt correction of:
• Malfunctioning dust collection systems• Inside bucket elevator failures:
• Overheated bearings and/or slipping/misaligned belts• Certified Inspection Record• LOTO
Grain Stream Processing EquipmentGrain Stream Processing Equipment
• Grain stream processing equipment shall be equipped with an effective means of removing ferrous material from the incoming grain stream.
Continuous-Flow Bulk Raw Grain Continuous-Flow Bulk Raw Grain DryersDryers
• All direct-heat grain dryers shall be equipped with automatic controls that: – Will shut-off the fuel supply in case of power or flame failure or
interruption of air movement through the exhaust fan; and, – Will stop the grain from being fed into the dryer if excessive
temperature occurs in the exhaust of the drying section. • Direct-heat grain dryers installed after March 30, 1988 shall
be: – Located outside the grain elevator; or – Located in an area inside the grain elevator protected by a fire or
explosion suppression system; or – Located in an area inside the grain elevator which is separated
from other areas of the facility by construction having at least a one hour fire-resistance rating
Inside Bucket ElevatorsInside Bucket Elevators
•Bucket elevators shall not be jogged to free a choked leg.
•Belts and lagging shall be conductive• < 300 Megaohms electrical resistance rating
•Bucket elevators shall have a means of access to:• Head pulley area• Boot area
Inside Bucket ElevatorsInside Bucket Elevators
•Bearing are to be mounted external to leg casing Bearing monitoring device is required
Belt monitoring Motion detection device – to indicate choking condition Belt alignment device
Hazard Monitoring DevicesHazard Monitoring Devices
Sample Motion Probe Located on Tail Shaft of Bucket Elevator
Hazard Monitoring DevicesHazard Monitoring Devices
Bearing Temperature Monitoring Sample Display Internal Hot Bearing Sensor
Installed Through Grease Fitting
Hazard Monitoring DevicesHazard Monitoring Devices
Belt Alignment Monitoring
NFPA 61 – Standard for the Prevention of NFPA 61 – Standard for the Prevention of Fires and Dust Explosions in Agricultural Fires and Dust Explosions in Agricultural and Food Processing Facilitiesand Food Processing Facilities
1-Administration 2-Referenced Publications 3-Definitions 4-Construction
Requirements 5-Ventilation and Venting 6-Explosion Prevention,
Relief, and Venting 7-Equipment
8-Dryers 9-Heat Transfer
Operations 10-Dust Control 11-Pneumatic Conveying 12-Building Fire
Protection 13-Supplemental
Requirements
QUESTIONS?QUESTIONS?