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Engineering Controls for Silica

Engineering Controls for Silica. Art Wickman, CIH Georgia Tech Safety & Health Consultation Program. Control Options. 1. Wet Methods 2. Ventilated Tools 3. Abrasive Blasting Controls: Alternate Media Alternate Methods. Engineering Controls: 1. Wet Methods. Water suppression of dust

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Engineering Controls for Silica

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  1. Engineering Controls for Silica • Art Wickman, CIH • Georgia Tech Safety & Health Consultation Program

  2. Control Options • 1. Wet Methods • 2. Ventilated Tools • 3. Abrasive Blasting Controls: • Alternate Media • Alternate Methods

  3. Engineering Controls:1. Wet Methods • Water suppression of dust • Very effective method • Requires planning for supply of water and clean up

  4. Note: Safety Glasses Required

  5. Wet Methods: Portable Saw

  6. Block Cutting: Dry Monitoring Data: • 8 X OSHA PEL • Time Weighted Average (TWA)

  7. Block Cutting--Dry

  8. Wet Methods: Block Cutting

  9. Wet Methods: Requires Pre-planning

  10. Wet Methods: Joint Cutting

  11. Wet Methods: Jack hammer, chipping hammer, etc.

  12. Double click photo for demo

  13. Wet Methods: Spray Systems for Bulk Materials

  14. Engineering Controls2. Ventilation • Portable tools with dust exhaust: • Surface Grinders • Disc Grinders (tuck pointing) • Crack chaser • Scarifier • Descaler • Power chipping tools • Retrofit Dust hoods (Dust Muzzle Video)

  15. Tuckpointing Note: Fall Protection Required

  16. Control by Ventilation: Tuckpointing

  17. Control by Ventilation: Tuckpointing

  18. Note: Safety Glasses Required • Control by Ventilation: Slab Cutting

  19. Control by Ventilation: Hand tools

  20. 3. Abrasive Blasting

  21. Engineering Controls:3. Substitute Abrasives • Coal slag (Low silica content, but may contain trace metals including arsenic) • Steel grit & steel shot • Aluminum oxide • Sodium Bicarbonate • (baking soda) • Dust Suppressed Sand • Frozen CO2 • Ag. Prod. (walnut shells, corn cobs)

  22. Substitute Abrasives: Blast and Recovery Systems • Permits multiple cycles of abrasive • Reduces cost of more expensive abrasives • Reduces fugitive emissions to Environment

  23. Alternate Abrasive Methods: Wet Blasting Similar to conventional air blasting • Water injected into air/abrasive stream, or • Water pressurized with abrasive • Work rate <50% of dry abrasive • Abrasive consumption <20% of dry • Better visibility, lower waste volume

  24. Alternative Blast Method: Enclosure

  25. Alternate Abrasive Methods: Water Jetting • 1. High Pressure • 10,000 – 25,000 psi • Removes most paint, rust, mill scale, chemical contaminants • 2. Ultra High Pressure • >25,000 psi • Removes all coatings • Processes can use vacuum shroud to retain/recycle water

  26. Alternate Abrasive Methods: Sponge Jet Blasting • Dry method, suppressed dust, minimal containment required • Light to heavy abrasion • Less aggressive cleaning • Eliminates the hazards of high pressure blasting

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