🦫Intro to Chemical Engineering Unit 12 – Safety and Risk Management in Chemical Engineering

Key Concepts and Definitions

• Hazard a potential source of harm or adverse health effect on a person or persons
  • Can be classified as physical, chemical, biological, or ergonomic
• Risk the likelihood and severity of a hazard causing harm
  • Assessed by considering both the probability and consequences of an event
• Safety the control of recognized hazards to achieve an acceptable level of risk
  • Involves identifying, evaluating, and mitigating potential dangers
• Process Safety Management (PSM) a systematic approach to preventing and mitigating the consequences of catastrophic releases of toxic, reactive, flammable, or explosive chemicals
• Inherent Safety the concept of designing processes and equipment to eliminate or minimize hazards, rather than relying on add-on safety systems
  • Includes principles such as substitution, minimization, moderation, and simplification
• Layer of Protection Analysis (LOPA) a semi-quantitative risk assessment method that identifies independent protection layers (IPLs) and estimates the risk reduction achieved by each layer
• Fault Tree Analysis (FTA) a top-down, deductive failure analysis method that uses Boolean logic to combine a series of lower-level events and determine the probability of a top event occurring

Hazard Identification Techniques

• Preliminary Hazard Analysis (PHA) a qualitative technique used early in the design process to identify potential hazards and assess their severity and likelihood
• Hazard and Operability Study (HAZOP) a systematic, team-based approach that examines each part of a process to identify potential deviations from the intended design and their consequences
  • Uses guide words (e.g., "no," "more," "less") to prompt discussion and identify hazards
• What-If Analysis a brainstorming technique that uses a series of questions to identify potential hazards and their consequences
  • Often combined with checklist analysis to ensure comprehensive coverage
• Failure Mode and Effects Analysis (FMEA) a bottom-up, inductive analysis technique that identifies potential failure modes, their effects, and the criticality of each failure
• Checklist Analysis a technique that uses pre-established lists of hazards, requirements, or best practices to identify potential issues and ensure compliance
• Consequence Analysis a quantitative technique that models the potential effects of a hazardous event, such as a chemical release or explosion
  • Uses tools like dispersion modeling and fire and explosion modeling to estimate the impact on people, property, and the environment

Risk Assessment Methods

• Quantitative Risk Assessment (QRA) a method that uses numerical data and models to estimate the probability and consequences of potential hazards
  • Involves techniques such as event tree analysis, fault tree analysis, and consequence modeling
• Semi-Quantitative Risk Assessment a method that uses a combination of numerical and qualitative data to estimate risk
  • Techniques include risk matrices, risk graphs, and calibrated risk assessment
• Qualitative Risk Assessment a method that uses descriptive scales (e.g., high, medium, low) to categorize the likelihood and severity of potential hazards
  • Often used as a screening tool to prioritize risks for further analysis
• Risk Matrix a tool that combines the likelihood and severity of a hazard into a single risk rating
  • Helps prioritize risks and determine appropriate risk reduction measures
• As Low As Reasonably Practicable (ALARP) a principle that states that risks should be reduced to a level that is as low as reasonably practicable, considering the costs and benefits of risk reduction measures
• Risk Acceptance Criteria the level of risk that is deemed acceptable by an organization or society
  • Can be based on factors such as industry standards, regulatory requirements, and societal expectations

Safety Regulations and Standards

• Occupational Safety and Health Administration (OSHA) a U.S. federal agency that sets and enforces standards for workplace safety and health
  • Relevant standards include the Process Safety Management (PSM) standard (29 CFR 1910.119) and the Hazard Communication standard (29 CFR 1910.1200)
• Environmental Protection Agency (EPA) a U.S. federal agency responsible for protecting human health and the environment
  • Administers the Risk Management Plan (RMP) rule (40 CFR Part 68), which requires facilities that use certain hazardous substances to develop and implement risk management programs
• National Fire Protection Association (NFPA) a U.S.-based nonprofit organization that develops and publishes consensus codes and standards related to fire, electrical, and life safety
  • Relevant standards include NFPA 30 (Flammable and Combustible Liquids Code) and NFPA 70 (National Electrical Code)
• American Institute of Chemical Engineers (AIChE) a professional organization that develops and disseminates best practices and technical resources for chemical engineering
  • Publishes the Center for Chemical Process Safety (CCPS) guidelines, which provide guidance on process safety management and risk assessment
• International Organization for Standardization (ISO) an international standard-setting body that develops and publishes standards for various industries
  • Relevant standards include ISO 45001 (Occupational Health and Safety Management Systems) and ISO 31000 (Risk Management)

Process Safety Management

• Process Safety Information (PSI) the collection and documentation of information necessary to conduct a process hazard analysis and operate a process safely
  • Includes information on the hazards of the chemicals used, the technology of the process, and the equipment in the process
• Process Hazard Analysis (PHA) the identification and evaluation of hazards associated with a process, and the identification of necessary control measures
  • Must be updated every five years or when a major change occurs
• Operating Procedures written instructions that provide clear, step-by-step directions for safely conducting activities involved in each covered process
  • Must be reviewed and certified annually
• Training the provision of initial and refresher training to ensure that employees understand the hazards of the process and the procedures for safe operation
  • Must be documented and verified
• Mechanical Integrity (MI) the establishment and implementation of written procedures to maintain the ongoing integrity of process equipment
  • Includes inspection, testing, and preventive maintenance of equipment such as pressure vessels, piping systems, relief and vent systems, and emergency shutdown systems
• Management of Change (MOC) the establishment and implementation of written procedures to manage changes to process chemicals, technology, equipment, and procedures
  • Ensures that the impact of changes on safety and health is evaluated and controlled
• Pre-Startup Safety Review (PSSR) the confirmation that construction and equipment are in accordance with design specifications, safety and operating procedures are in place, and process hazard analysis recommendations have been addressed prior to introducing highly hazardous chemicals to a process

Accident Prevention Strategies

• Inherently Safer Design the concept of eliminating or reducing hazards through the selection of less hazardous materials, minimizing inventory, and designing simpler, more robust processes
  • Applies principles such as substitution, minimization, moderation, and simplification
• Layers of Protection the use of multiple, independent safeguards to prevent or mitigate the consequences of a hazardous event
  • Includes passive, active, and procedural safeguards
• Safety Instrumented Systems (SIS) a system composed of sensors, logic solvers, and final elements designed to bring a process to a safe state when predetermined conditions are violated
  • Designed and managed according to standards such as IEC 61508 and IEC 61511
• Permit-to-Work Systems a formal, written system used to control certain types of work that are potentially hazardous
  • Ensures that work is properly authorized, the hazards are identified and controlled, and communication between work groups is effective
• Management of Change (MOC) Procedures a systematic approach to evaluating and controlling the risks associated with changes to a process
  • Ensures that the impact of changes on safety, health, and the environment is thoroughly assessed and managed
• Process Safety Culture the shared values, beliefs, and behaviors that determine how an organization views and manages process safety
  • Includes elements such as leadership commitment, employee involvement, open communication, and continuous improvement
• Human Factors the study of how people interact with their work environment, tools, and equipment
  • Considers factors such as workload, fatigue, communication, and human-machine interface design to optimize human performance and minimize the potential for human error

Emergency Response Planning

• Emergency Response Plan (ERP) a written document that outlines the actions to be taken in the event of an emergency, such as a fire, explosion, or chemical release
  • Includes elements such as emergency contact information, evacuation procedures, and roles and responsibilities of emergency response personnel
• Incident Command System (ICS) a standardized approach to the command, control, and coordination of emergency response
  • Provides a common hierarchy and structure for managing resources and communication during an incident
• Emergency Notification Systems systems used to alert personnel of an emergency and provide instructions for appropriate response
  • Can include audible and visual alarms, text messaging, and email notifications
• Evacuation Procedures pre-planned procedures for safely and efficiently evacuating personnel from a facility in the event of an emergency
  • Includes elements such as evacuation routes, assembly points, and head count procedures
• Shelter-in-Place Procedures pre-planned procedures for safely sheltering personnel within a facility in the event of an emergency where evacuation is not possible or advisable
  • Includes elements such as shelter locations, air handling system controls, and communication protocols
• Emergency Drills and Exercises regularly scheduled simulations of emergency scenarios used to test and improve emergency response capabilities
  • Can include tabletop exercises, functional drills, and full-scale exercises
• Post-Incident Investigation a systematic process for gathering and analyzing information about an incident to determine its causes and identify corrective actions to prevent recurrence
  • Includes elements such as root cause analysis, timeline development, and recommendations for improvement

Case Studies and Lessons Learned

• Bhopal Disaster (1984) a catastrophic chemical release at a Union Carbide pesticide plant in Bhopal, India, resulting in thousands of deaths and injuries
  • Lessons learned include the importance of inherent safety, effective emergency response, and corporate responsibility
• BP Texas City Refinery Explosion (2005) a series of explosions and fires at a BP refinery in Texas City, Texas, resulting in 15 deaths and 180 injuries
  • Lessons learned include the importance of process safety culture, effective management of change, and learning from previous incidents
• Deepwater Horizon Oil Spill (2010) a massive oil spill in the Gulf of Mexico resulting from the explosion and sinking of the Deepwater Horizon drilling rig
  • Lessons learned include the importance of effective risk assessment, emergency response planning, and regulatory oversight
• Fukushima Daiichi Nuclear Disaster (2011) a series of equipment failures, nuclear meltdowns, and releases of radioactive materials at the Fukushima Daiichi Nuclear Power Plant in Japan following a severe earthquake and tsunami
  • Lessons learned include the importance of designing for extreme events, effective emergency response, and transparent communication
• West Fertilizer Company Explosion (2013) a massive explosion at a fertilizer storage and distribution facility in West, Texas, resulting in 15 deaths and more than 160 injuries
  • Lessons learned include the importance of community planning, emergency response coordination, and the safe storage of hazardous materials
• Chevron Richmond Refinery Fire (2012) a fire at a Chevron refinery in Richmond, California, caused by a corroded pipe, resulting in a large plume of smoke and thousands of residents seeking medical attention
  • Lessons learned include the importance of effective mechanical integrity programs, incident investigation, and community outreach
• DuPont La Porte Facility Toxic Chemical Release (2014) a toxic chemical release at a DuPont chemical plant in La Porte, Texas, resulting in four employee fatalities
  • Lessons learned include the importance of effective process safety management, emergency response planning, and the use of inherently safer design principles