Hierarchy of Controls for Process Safety

To effectively mitigate risks associated with any process, a systematic approach based on the hierarchy of controls should be implemented. This involves prioritizing control measures from the most effective to the least effective, ensuring comprehensive protection for workers, the environment, and property.

Elimination

Elimination involves removing the hazard entirely from the workplace, which is the most effective control measure. This approach prevents exposure and eliminates the risk at its source.

Examples of elimination strategies include:

• Removing a hazardous step from the process if it is not essential. For example, removing a step in a process that is not needed.

[1] Substitution

If elimination is not feasible, substitution involves replacing a hazardous substance or process with a less hazardous alternative. This reduces the severity of potential incidents.

Examples of substitution strategies include:

• Replacing solvent-based paints with water-based alternatives to reduce exposure to harmful vapours.
• Using a larger granule form of a product instead of a fine powder to reduce dust generation.
• Replacing a highly toxic and flammable chemical used in a process with a safer alternative. For example, replacing a highly toxic and flammable chemical used in a process with a safer alternative.

[2] [2] [1] Engineering Controls

Engineering controls involve implementing physical changes to the workplace to isolate or minimize exposure to hazards. These controls are generally more reliable than administrative controls and PPE because they do not rely on human behavior.

Examples of engineering controls include:

• Installing appropriate ventilation systems to remove airborne contaminants.
• Using pressure or explosion relief venting to prevent over-pressurization.
• Implementing automated process controls to maintain safe operating parameters (e.g., temperature, pressure, flow, safe shutdowns).
• Providing a backup power supply in the event of a power failure.
• Using protective barriers, enclosures, and isolation to separate workers from hazards.
• Using electrical equipment that is designed for hazardous locations (as required by the applicable electrical code).
• Implementing appropriate interlocks to prevent unsafe conditions.
• Installing appropriate fire detection and suppression systems (as specified in the applicable fire code).
• Using mechanical lifting devices to reduce the risk of strain injuries.
• Installing guardrails to prevent falls.
• Enclosing the material or process in a closed system (e.g., enclosed machines, booths, etc.).
• Using guards around moving parts of machinery.
• Using local exhaust or general dilution ventilation to remove or reduce airborne products.

[1] [1] [1] [1] [1] [1] [1] [1] [3] [3] [3] [3] [3] Administrative Controls

Administrative controls involve implementing policies, procedures, and training programs to reduce the risk of exposure to hazards. These controls rely on human behavior and are generally less effective than elimination, substitution, or engineering controls.

Examples of administrative controls include:

• Developing and implementing safe work procedures or standard operating procedures.
• Training and educating employees about operating procedures and workplace hazards (including WHMIS).
• Implementing a preventative maintenance program to keep equipment in proper working order.
• Scheduling maintenance and other high-exposure operations for times when few workers are present.
• Restricting access to a work area.
• Restricting the task to only those competent or qualified to perform the work.
• Using signs to warn workers of a hazard.
• Using job-rotation schedules or work-rest schedules to limit exposure time.
• Implementing a preventative maintenance program.
• Developing clear instructions for workers on how to monitor and operate the process safely under all potential conditions.
• Developing emergency response procedures.
• Developing business continuity plans.

[7] [7] [7] [7] [7] [7] [7] [7] [7] [6] [6] [6] Personal Protective Equipment (PPE)

PPE is the last line of defense and should be used in conjunction with other control measures. PPE includes equipment worn by individuals to reduce exposure to hazards.

Examples of PPE include:

• Respiratory protection.
• Head protection.
• Skin protection.
• Eye and face protection.
• Gloves.
• Protective footwear.

[6] Additional Considerations

Several additional considerations are crucial for ensuring the effectiveness of safety measures:

Risk Assessment

Conducting a thorough risk assessment is essential for identifying potential hazards and evaluating the likelihood and severity of potential incidents. This assessment should involve a team of knowledgeable individuals, including supervisors and workers directly involved in the process. [4]

Incident Investigation

Establish a process for investigating incidents to identify underlying causes and prevent recurrence. Incident investigations should focus on obtaining facts and not placing blame. [9] [9]

Emergency Preparedness

Develop and implement an emergency action plan that includes procedures for evacuation, handling releases of hazardous chemicals, and providing support for employees with physical impairments. [9] [9]

Training and Communication

Provide comprehensive training to workers on all aspects of process safety, including hazard identification, risk assessment, control measures, and emergency procedures. Ensure that workers are aware of the hazards associated with their jobs and the controls in place to protect them. [4]

Management of Change

Establish a system for managing changes to processes, equipment, and procedures. This system should include a review of potential hazards and risks, as well as the implementation of appropriate control measures. [5]

Continuous Monitoring and Review

Implement a system to continuously monitor the safety of the process and the effectiveness of the controls. Regularly review and evaluate the hazard control program to ensure that it remains effective. [8] [4]

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