Welding Guide Study Notes

HAZARDS POLICY INSPECTION

  • Introduction: The guideline serves as a resource for employers and workers to safely perform welding activities, providing comprehensive information on various aspects involved in welding safety.

TABLE OF CONTENTS

  • Workplace Safety and Health Regulation Requirements

  • Reference Standards/Documents

  • Risk Evaluation

  • Safe Work Procedures

  • Welding Hazards and Control Measures   - What is Welding?   - Types Of Welding Processes     - Electric Arc Welding     - Combustion Gas Welding     - Laser and Allied Processes   - Welding Hazards     - Airborne Hazards – Fumes     - Airborne Hazards – Gases     - Noise Hazards     - Radiation Hazards     - Ergonomic Hazards     - Electrical Hazards     - Burn Hazards     - Fire and Explosion Hazards     - Other Hazards   - Basic Welding Control Measures

  • Physical Hazards Management

  • Special Welding Situations

  • Welding Safety Checklist

  • References and Additional Reading

INTRODUCTION

  • Purpose: To provide employers and workers with guidelines to safely conduct welding activities.

  • Coverage: The guideline includes information on:   - Types of welding processes   - Identified hazards   - Health effects of exposure to hazards   - Allowable thresholds and guidelines   - Ventilation guidelines   - PPE requirements   - Special welding situations   - Checklist and references for further reading

WORKPLACE SAFETY AND HEALTH REGULATION REQUIREMENTS

  • Governed by the Manitoba Workplace Safety and Health Regulation (M.R. 217/2006).

  • Standards include:   - CAN/CSA Standard W117.2-06 (R2011), addressing safety in welding, cutting, and allied processes.   - Welders Health and Safety Guide by CCOHS.   - Recommendations from ACGIH regarding TLVs and BEIs.

RISK EVALUATION

  • To assess workplace welding hazards, conduct a job hazard analysis which breaks down tasks into steps to identify hazards.

  • Develop control measures and safe work procedures post hazard identification.

  • Refer to SAFE Work Bulletins for guidance on job hazard analysis.

SAFE WORK PROCEDURES

  • Mandatory Procedures: Employers must create and implement safe work procedures prior to starting any welding project.

  • Resources: Refer to SAFE Work Bulletin #249(2) for guidelines and templates.

WELDING HAZARDS AND CONTROL MEASURES

What is Welding?

  • Welding joins metals using pressure, heat, flame, and/or electrical arc.

  • Involves heating a filler metal which, upon cooling, forms a strong joint between work pieces.

  • Fume Generation: 90% of welding fumes are generated from the melting of the consumable electrode.

  • Fume Composition: A mixture of base metal, flux, and consumable wire/electrode materials. Refer to supplier’s MSDS for details.

Types Of Welding Processes

  • A. Electric Arc Welding:   - Uses an electric arc to generate temperatures of 3,000º to 30,000ºC.   - Key Processes:     1. Shielded Metal Arc Welding (SMAW): Known as stick welding; uses a consumable electrode.     2. Gas Tungsten Arc Welding (GTAW): Uses non-consumable tungsten electrode with shielding gas, primarily for aluminum and stainless steel.     3. Gas Metal Arc Welding (GMAW): Also known as MIG; continuous wire is fed through the welding gun.     4. Flux Cored Arc Welding (FCAW): Characteristics similar to GMAW but uses a tubular wire filled with flux.     5. Plasma Arc Welding (PAW) and Plasma Arc Cutting (PAC): Uses a constricted arc for precision cutting and welding.     6. Submerged Arc Welding (SAW): Arc is covered by granular flux which minimizes fume generation.     7. Resistance Welding: Produces weld through electric current and mechanical pressure.

Welding Hazards

  • Airborne Hazards – Fumes:   - Fine solid particles created above the boiling point of metals; generally <1 micron in diameter. Health risks depend on type and amount of fumes generated.

  • Airborne Hazards – Gases:   - Produced from burning shielding gases or with the reaction to UV light. Significant gases include ozone (irritating), carbon monoxide (asphyxiant), nitrogen oxides (irritating), etc.

  • Noise Hazards:   - Constant exposure to noise >85 dBA can lead to hearing loss; practices for minimizing exposure include equipment modifications.

  • Radiation Hazards:   - Include visible light, UV radiation (can cause skin burns), and potential for welders’ flash (photokeratitis).

  • Ergonomic Hazards:   - Physical strain and risk of musculoskeletal injuries due to awkward postures; recommended interventions include ergonomic assessments and proper tool selection.

  • Electrical Hazards:   - Electric shock risk from ungrounded or improperly installed equipment.

  • Burn Hazards:   - Thermal burns from hot metal, or UV burns.

  • Fire and Explosion Hazards:   - Risks due to flammable materials and improper ventilation in welding areas.

Basic Welding Control Measures

  • Substitute Welding Wires: Introduce less hazardous materials to minimize fume generation.

  • Ensure Proper Ventilation: Design hoods for efficiency using recommendations for air flow rates.   - Types include:     - Enclosing hoods for localized captures.     - General ventilation for low-level contaminants.

  • Adapt Engineering Controls: Use shrouds to limit ozone exposure and remove contaminants effectively.

  • Work Practices: Include regular training to observe safety practices and control measures.

SPECIAL WELDING SITUATIONS

Confined Space

  • Requires continuous ventilation and monitoring due to lethal hazards such as low oxygen and flammable vapors.

  • Precautions: Use portable ventilation and gas monitors.

Brazing and Soldering

  • Similar processes for joining metals; brazing operates above 450ºC and produces fumes containing toxic substances.

Robots

  • Safety measures must be in place to prevent injuries due to unexpected robot motions; training in programming and maintenance is crucial.

Welding or Cutting Containers

  • Identify former contents; ensure all containers are clean and vented before operation to avoid combustion.

Hot Work Permit

  • Required before any hot work activity in the vicinity of flammable materials; implement comprehensive safety checks.

Laser Welding

  • Intense coherent light used; safety measures must include protective barriers and proper eyewear due to potential eye and skin hazards.

WELDING SAFETY CHECKLIST

  • Ensure proper inspection of welding areas, availability of materials (MSDS), and health monitoring of welders for signs related to welding hazards.

REFERENCES AND ADDITIONAL READING

  • Comprehensive list of sources such as guidelines from ACGIH, CCOHS, and industry-specific literature to assist in understanding safety practices in welding.