Workplace Hazard Control

• Main goal of hazard control is to eliminate or reduce negative impacts from workplace incidents.
• Safety engineers decide how to protect workers, the environment, and the community from hazards after they are identified.
• Hazard elimination is not always feasible due to cost or technology limits.

Hazard Control Hierarchy

• Inherent safety is the primary method.
• Engineering controls are used, these relate to equipment measures.
• Administrative controls are applied, these are documented procedures.
• PPE (personal protective equipment) are needed.

Inherent Safety

• Designed to use chemistry and physics instead of control systems to prevent accidents.
• It is better mitigate hazards instead of trying to control them.
• Principles include: Elimination, Minimization, Substitution, Attenuation, Limitation of Effects, and Simplification.

Engineering Controls

• These are physical changes or designs which reduce risks from machinery, operations and chemical processes.
• Designed to prevent hazardous incidents, or reduce the impacts of those incidents.

Safety Instrumented Systems (SIS)

• Automated and emergency shutdown systems are used.
• Emergency shutdown (ESD) valves are integrated.

Pressure Relief Devices

• Pressure safety valves (PSV) are used.
• Pressure Relief Valves are also used.

Containment and Isolation

• Double-walled tanks for extra protection.
• Leak-proof piping and isolation valves.

Ventilation and Extraction Systems

• Localized exhaust ventilation is used for removing toxic gases and vapors.
• Explosion-proof ventilation designs are used.

Pressure Relief Valves

• Designed to open proportionally when pressure in a system increases.
• They open enough to relieve excess if the pressure rises above set point.
• They use a spring-loaded mechanism for pressure adjustment..
• Designed to respond to minor pressure variations without a full shutdown.

Pressure Safety Valves (PSV)

• This valve quickly releases gasses from equipment preventing over-pressurization and potential accidents.
• PSVs activate automatically when exceeding pressure limits to ensure safe pressure levels.

Automatic Detection and Alarm Systems

• Gas, smoke, fire, and leak detectors with alarms and automatic actions.

Process Control and Automation

• Distributed control systems (DCS) are used to maintain functional parameters.
• Redundant control systems and interlocks are included.

Emergency Containment Structures

• Dikes and bunds are used surrounding chemical storage tanks.
• Secondary containment areas are built.

Gas Detectors

• Used in critical safety monitoring which detects hazardous gasses.
• Flamable gas detectors detect combustible gasses, like methane, propane, butane, hydrogen.
• Toxic gas detectors detect hazardous gasses.

Fail-Safe Design

• When process variables reach undesirable ranges, the system defaults to a fail-safe state automatically.
• Automatic shutdown devices activate based on temperature, pressure, flow, level, and process composition.
• Puts the system in the safest state and only restarts with user intervention.

Redundancy

• Systems function normally even if there are failures of instruments, control functions, or motors.
• Achieved through redundant controls, equipment, measurements, paths, and actuators.
• Based on how critical an event is to the workers' safety, process continuation, and potential cost.

Weak-Link

• Designed to fail at a certain stress level which controls and minimizes failure or accidents.
• Used in electrical, mechanical, and structural safety systems.
• Electrical fuses protect valuable parts by failing first.

Alarms

• Alert process engineers to abnormal conditions.
• Typically audible and or visual

Process Alarms

• High/Low Alarms trigger when there are limit breaches in temp, pressure or flow.
• Rate of Change Alarms engage when abrupt process variable changes occur, indicating potential issues.
• Deviation Alarms act when there is a gap between the setpoint and actual value of a system.

Safety Alarms

• Emergency Shutdown (ESD) Alarms initiate the process' shutdown when something critical is detected.
• Fire and Gas Alarms detect smoke, flames, or gas leaks.
• Leak Detection Alarms detect leaks in hazardous material systems.

Equipment Alarms

• Mechanical Failure Alarms are used to detect faults in equipment
• Power Failure Alarms detect issues with power supply.
• Vibration Alarms detect unusual equipment vibrations.

Flares

• Used to burn off waste gases and emergency dumps.
• Prevent the release of toxic gases, by controlled burning
• Waste gases pass to a flare header and are burned.

Pressure Relief

• Pressure relief Valves are used to protect vessels or piping.
• They protect against over pressure.
• Released material empties into the flare header.

Explosion Suppression

• Walls are built to contain explosions.
• Blast walls are built around units or vessels with unstable/reactive materials.

Bunds and Dikes

• Contain spills and direct them to a safe location.
• Designed to contain contents of a ruptured or leaking tank.

Isolation, Lockouts, Lockins, and Interlocks

• Based on three safety principles
• Isolating a hazard once recognized.
• Preventing incompatible events from occurring, occurring at the wrong time, or in the wrong order.
• Providing a release after proper steps.

Administrative Controls

• Procedures to limit employee exposure to hazards.
• Influence worker behavior through procedures.
• Enforcement is achieved through penalties.
• Divided into two broad categories:
  • Programs: Written documents.
  • Activities: Programs put into action.

Administrative Controls - Items

• Documents explaining hazards are put in frames and displayed in strategic locations.
• New employees get administrative program copies at orientation.

Common Administrative Controls

• Policy Statements: Business guiding principles.
• Principles: Rules or standards.
• Rules: Statements of action or inaction.
• Plans: Methods prepared for actions.
• Procedures: Step-by-step task instructions.

Evacuation and Accountability Plans

• Document outlines routes and assembly spots for safe evacuation and headcounts.
• Manufacturing sites have evacuation routes and assembly areas.
• Assembly spots depend on the hazard.
• Verification by headcounts are used.

Cardinal Rules

• Very important rules with stern consequences of breaking them.
• A breach of the rules can cause safety/environmental incidents.
• Not issued by regulatory agencies, however considered important in process industry.

Cardinal Rules - Examples

• Prohibition of Alcohol, drugs, firearms, violence, matches/lighters in certain areas.

Mutual Aid Agreements

• Agreements between manufacturing sites and local governments for aid.
• Plants with hazardous materials must have fire/first-aid teams.
• Plants should form agreements for emergency responses.
• Large fires require radio calls across sites to bring support.

Buddy Sytem

• Hazardous tasks require dual support.
• Used to monitor and safeguard hazardous operation personnel.
• Has two main methods:
  • Two persons at the same hazard at the same time look out for each other.
  • Only One is exposed to hazard and the other's main task is to protect and support the individual in danger.

Hazard Communication (HAZCOM)

• Hazard communication ensures information on produced chemicals are passed to employees.
• Covers commerically valuable products or solvents.
• A written HAZCOM is a blueprint on ensuring safety.

Types of Labels (NFPA and HMIS)

• NFPA diamonds and HMIS bar color and number coded providing hazard information.
• DOT symbols are on shipping cartons.

NFPA Diamond

• NFPA 704 provides hazard communication for emergency responders.
  • Red signifies Flammability.
  • Blue indicates Health hazard.
  • Yellow shows Instability/Reactivity.
  • White details Special notes.

HMIS (Hazardous Materials Identification System)

• HMIS details: -Blue Health Hazards, 4 is life threatening. -Red is Flammability, 4 is flammable gasses or liquids. -Orange gives details on physical hazards. -White defines use of personel protective Equipment.

Administrative Activites

• These put the programs into action.
• Activities may include:
  • Training which provides instruction on tasks.
  • Housekeeping for orderly workplaces.
  • Safety Inspections to maintain health.
  • Permint system to ensure the area is safe to start.
  • Safety audits to keep track of regulatory requirements.
  • Investigations is a root cause determination.
• This requires support of the budget and management from safety activities.

Persona Protective Equipment (PPE)

• Worn for protection against accidents.
• Negligence for PPE results in laziness, risk, and discomfort of wearing them.
• Management must encourage the use of this, and enforce.
• Needs for PPE are categorized into hazardous, investigative and corrective operations.