Dozer Engulfment Case Study
description
Transcript of Dozer Engulfment Case Study
Dozer Engulfment Case Study
Jack KatlicSr VP-Fuel Supply, AEP- Retired
Mark SkilesDirector of Technical Support, MSHA
Phil SouthernBodygard
Sunnie SouthernBodygard
Dozer Engulfment Case Study
• Agenda– Surge Pile Hazards
– Surge Pile Accidents
– Solutions for Stronger Cab Windows
– Demonstration
– Conclusion
– Panel Discussion
Dozer Engulfment Case Study
• Purpose– Share one method the coal industry has implemented to save lives
Surge Pile Hazards
Surge Pile Safety
Directorate of Technical Support Mine Safety and Health Administration
Slides with the MSHA logo were adapted from the MSHA website and can be found at: www.msha.gov
Surge Pile Hazards
• Feeding material acts like “quicksand”
Surge Pile Hazards
• The edge of the drawhole is unstable
Surge Pile Hazards
• Poor visibility
Surge Pile Hazards
• Since 1980, 19 persons have died in coal mining related surge pile accidents
• Most of the accidents have involved a hidden cavity created when material “bridged” over a feeder
Causes of “Bridging” Over a Surge Pile Feeder
• Bridging can occur– When equipment transverses
the material at the surface of the pile
– Surface material compacts creating a false roadway
– “Settling in” may occur in an idle pile and increase risk
Surge Pile Accidents
Note the thickness of the material that had been bridged over
Dozer Buried in Cavity
A hidden cavity collapsed under the dozer while it was pushing coal on the pile
Partially Buried Bulldozer in Fatal Accident in Pennsylvania
• Most fatal accidents occurred when the dozer cab windows either broke, or were pushed into the cab, allowing coal to fill the cab
Cab Filled with Coal
The coal has broken or pushed in the cab windows and filled the cab
Note: orange object under windshield is an self contained self rescuer (SCSR)
Windshield pushed back into cab
Best Practices: Ways to Improve Surge Pile Safety
Best Practices: Surge Pile Safety
• Provide equipment cabs strong enough to resist burial pressures
Solutions for Stronger Cab Windows
Available Solutions for Stronger Cab Windows
• MSHA initiative– Use of very high-strength glass
• Massey approach– Add supports to the inside of the cab windows - combined with using
somewhat stronger glass
• Use of polycarbonate windows – Adequate strength– Support around edges needs to allow for higher deflection – Issue of scratch-resistance
• Bodygard system– A customized polycarbonate system
Massey Subkit
Massey Subkit
• The first system
• Most widely used
• Effective in saving lives
• System design– is comprised of metal bars attached to the inside of the cab
– keep the cab and glass from collapsing on the operator
The Massey Approach
•Installed support bars on the inside of the cab windows
•The supports for the right-side door window are shown here
•Horizontal support bars and additional edge support for the windshield are shown here
The Massey Approach
•Massey’s successful burial demonstration
•The glass cracked but it held the coal out of the cab
The Massey Approach
Contrast this scene after the Massey demonstration - where coal was held out of the cab - with...
This scene from an accident, where coal has filled the cab...
Massey Subkit
• Advantages– Keeps cabs from
collapsing
– Least expensive
– Saves lives
• Disadvantages– Obscures vision especially
when backing up
– Causes cycildelic affects that result in complaints of headache from operators
– Metal bars rattle and increase noise level in the cabin
– Metal bars loosen and crack door glass that must be replaced
PPG Preformed Pre-designed Product
PPG Preformed Pre-designed Product
• Created as by request of MSHA to overcome the deficiencies of the subkit
• System design– A chemically hardened preformed pre-designed product
– Installed by gluing the glass into a gasket is installed in same manor as standard glass packages
High-strength glass installed using urethane adhesive
Field Burial Demonstration
Federal No. 2 Mine
Near Morgantown, WV
High-strength glass installed in all cab windows of test dozer
Dozer with high-strength glass being buried in coal pile
Buried dozer being dug out
Checking windows after burial
High-strength glass intact after burial demonstration
PPG
• Advantages– Does not obstruct vision
– Resists static pressure up to 40 psi
• Disadvantages– Preformed therefore
application is limited to Caterpillar and Komatsu dozer’s* standard cab packages
– Requires fixing of any deformation of the cab prior installation of the glass
– Most expensive
– May crack when impacted
– May pop-out under stress
PPG Preformed Pre-designed Product
Pounds per square inch
*Molds are only for dozers not for end loaders
Bodygard System
Bodygard System
• Custom engineered
• Custom installed
• Polycarbonate system– Outboard seat is created
– Material is mechanically attach to the cab
• Inhibits internal collapse
• Unbreakable
• Noise insulator
• On site installation
• All manufacturers
• MSHA approved
Case Study History
• Massey conducted drop tests of 3 systems to determine the most effective system
• The following demonstration shows the results of the test
Dozer Drop Test Demonstration
Body Guard
• Advantages– Unbreakable
– Does not obstruct vision
– Can be made to fit anything (all makes and models of existing equipment)
– Absorbs and insulates sound
– Broad based system
– Onsite customized installation on all cabs
– Installed on site by drilling and attaching to cab
– Cut to specs and attached to ensure stability
• Disadvantage*– Is less scratch resistant that
regular glass therefore a protective covering is applied that is easy and inexpensive to replace
Bodygard System
*Protective replicable material is applied to improve the scratch
resistance
Conclusion
• Based on the results of the drop test, Massey signed a national contract with Bodygard to perform their installations
BODYGARD
1 Lincoln Center, Shinnston, WV 26431
“The Safety Window People”
www.bodygard.com 304-592-1980