Whenever there are processes that use temperature and pressure to change the molecular structure or create new products from chemicals, the possibility exists for fires, explosions or releases of flammable or toxic liquids, vapours, gases or process chemicals. The control of these undesired events requires a special science called process safety management. The terms process safety and process safety management are most commonly used to describe the protection of employees, the public and the environment from the consequences of undesirable major incidents involving flammable liquids and highly hazardous materials. According to the United States Chemical Manufacturers’ Association (CMA), “process safety is the control of hazards which are caused by maloperation or malfunction of the processes used to convert raw materials into finished products, which may lead to the unplanned release of hazardous material” (CMA 1985).
Industry and labour process safety involvement
Process safety technology has played an important role in the chemical processing industries so that handling flammable and combustible liquids and gases could proceed without undesirable consequences. During the 1980s, the oil and gas industries, for example, recognized that process safety technology alone, without process safety management, would not prevent catastrophic incidents. With this in mind, a number of industry associations, such as, in the United States, the Center for Chemical Process Safety (CCPS), the American Petroleum Institute (API) and the Chemical Manufacturers' Association (CMA), initiated programmes to develop and provide process safety management guidelines for use by their members. As stated by the CCPS, "The evolution of process safety from a purely technical issue to one that demanded management approaches was essential to continued process safety improvement".
The CCPS was formed in 1985 to promote the improvement of process safety management techniques among those who store, handle, process and use hazardous chemicals and materials. In 1988, the Chemical Manufacturer's Association (CMA) initiated its Responsible Care® programme outlining each member company's commitment to environmental, health and safety responsibility in managing chemicals.
In 1990, the API initiated an industry-wide programme entitled, STEP-Strategies for Today's Environmental Partnership, with the intention of improving the oil and gas industry's environmental, health and safety performance. One of the seven strategic elements of the STEP programme covers petroleum operating and process safety. The following documents are examples of some of the materials developed as a result of the STEP programme which provide guidance to the oil and gas industry to help prevent the occurrence or minimize the consequences of catastrophic releases of flammable liquids and vapours or hazardous process materials:
- Management of Process Hazards (RP 750)
RP 750 covers the management of hydrocarbon process hazards in design, construction, start-up, operations, inspection, maintenance and facility modifications. It applies specifically to refineries, petro-chemical plants and major processing facilities that use, produce, process or store flammable liquids and toxic processing chemicals in quantities above certain hazardous amounts (as defined therein).
- Management of Hazards Associated with Location of Process Plant Buildings (RP 752)
RP 752, co-developed by API and CMA, is intended to help identify process plant buildings of concern, understand the potential hazards related to their location within the process facility and manage the risk of fire, explosion and toxic releases.
- Management Practices, Self-assessment Process, and Resource Materials (RP 9000)
RP 9000 provides resource materials and self assessment methodology to measure progress in implementing process safety management elements.
Examples of other organizations which have developed materials and programmes providing guidance covering chemical process safety management include, but are not limited to, the following:
- Organizations Resource Counselors' (ORC) report, Process Hazards Management of Substances with Catastrophic Potential
- National Petroleum Refiners Association (NPRA), BEST (Building Environmental Stewardship Tools) programme
- International Labour Organization (ILO), Code of Practice on the Prevention of Major Accident Hazards
- International Chamber of Commerce (ICC), Charter for Sustainable Development.cmp01ce.doc
The process design and technology, changes in the process, materials and changes in materials, operations and maintenance practices and procedures, training, emergency preparedness and other elements affecting the process must all be considered in the systematic identification and evaluation of hazards so as to determine whether or not they have the potential to lead to a catastrophe in the workplace and surrounding community.
Beginning in the early 1980s, a number of serious major incidents occurred in the petroleum and chemical industries involving highly hazardous materials, which resulted in considerable numbers of fatalities and injuries and significant property losses. These incidents provided the impetus for government agencies, labour organizations and industry associations throughout the world to develop and implement codes, regulations, procedures and safe work practices directed toward the elimination or mitigation of these undesirable events, through the application of the principles of process safety management. They are discussed more fully in the Disasters, natural and technological chapter and elsewhere in this Encyclopaedia.
In response to public concern over the potential hazards of chemicals, governments and regulatory agencies throughout the world initiated programmes which required manufacturers and users to identify hazardous materials in the workplace and inform employees and consumers of the hazards presented by their manufacture, use, storage and handling. These programmes, which covered emergency preparedness and response, hazard recognition, product knowledge, control of hazardous chemicals and reporting of toxic releases, included hydrocarbon processing.
Process Safety Management Requirements
Process safety management is an integral part of the overall chemical processing facility safety programme. An effective process safety management programme requires the leadership, support and involvement of top management, facility management, supervisors, employees, contractors and contractor employees.
Components to be considered when developing a process safety management programme include:
- Interdependent continuity of operations, systems and organization
- Management of information. The process safety management programme relies upon providing availability and access to good records and documentation.
- Control of process quality, deviations and exceptions and alternate methods
- Management and supervisory accessibility and communications. Because process safety management is the basis for all safety efforts within the facility, managerial, supervisory and employee responsibility and accountability should be clearly delineated, communicated and understood in order for the programme to work.
- Goals and objectives, compliance audits and performance measurement. Prior to implementation, it is important to establish both long-term and short-term goals and objectives for each of the elements of the process safety management programme.
Elements of the Process Safety Management Programme
All chemical facility process safety management programmes cover the same basic requirements, although the number of programme elements may vary depending on the criteria used. Regardless which government, company or association source document is used as a guide, there are a number of basic requirements which should be included in every chemical process safety management programme:
- process safety information
- employee involvement
- process hazard analysis
- management of change
- operating procedures
- safe work practices and permits
- employee information and training
- contractor personnel
- pre-startup safety reviews
- design quality assurance
- maintenance and mechanical integrity
- emergency response
- periodic safety audits
- process incident investigation
- standards and regulations
- trade secrets.
Process safety information
Process safety information is used by the process industry to define critical processes, materials and equipment. Process safety information includes all available written information concerning process technology, process equipment, raw materials and products and chemical hazards before conducting a process hazard analysis. Other critical process safety information is documentation relating to capital project reviews and design basis criteria.
Chemical information includes not only the chemical and physical properties, reactivity and corrosive data and thermal and chemical stability of chemicals such as hydrocarbons and highly hazardous materials in the process, but also the hazardous effects of inadvertently mixing different incompatible materials. Chemical information also includes that which may be needed to conduct environmental hazard assessments of toxic and flammable releases and permissible exposure limits.
Process technology information includes block flow diagrams and/ or simple process flow diagrams as well as descriptions of the chemistry of each specific process with the safe upper and lower limits for temperatures, pressures, flows, compositions and, where available, process design material and energy balances. The consequences of deviations in the process and materials, including their effect on employee safety and health, are also determined. Whenever processes or materials are changed, the information is updated and re-evaluated in accordance with the facility’s management of change system.
Process equipment and mechanical design information includes documentation covering the design codes employed and whether or not equipment complies with recognized engineering practices. A determination is made as to whether existing equipment which was designed and constructed in accordance with codes, standards and practices no longer in general use is maintained, operated, inspected and tested to assure continued safe operation. Information on materials of construction, piping and instrument diagrams, relief system design, electrical classification, ventilation design and safety systems is updated and re-evaluated when changes occur.
Process safety management programmes should include employee participation in the development and conduct of process safety analyses and other elements of the programme. Access to process safety information, incident investigation reports and process hazard analyses is usually provided to all employees and contractor employees working in the area. Most industrialized nations require that workers be systematically instructed in the identification, nature and safe-handling of all chemicals to which they may be exposed.
Process hazard analysis
After the process safety information is compiled, a thorough and systematic multi-disciplinary process hazard analysis, appropriate to the complexity of the process, is conducted in order to identify, evaluate and control the hazards of the process. Persons performing the process hazard analysis should be knowledgeable and experienced in relevant chemistry, engineering and process operations. Each analysis team normally includes at least one person who is thoroughly familiar with the process being analysed and one person who is competent in the hazard analysis methodology being used.
The priority order used to determine where within the facility to begin conducting process hazard analyses is based on the following criteria:
- extent and nature of the process hazards
- number of potentially affected workers
- operating and incident history of the process
- age of the process.
A number of methods for conducting process safety analyses are used in the chemical industry.
The “what if?” method asks a series of questions to review potential hazard scenarios and possible consequences and is most often used when examining proposed modifications or changes to the process, materials, equipment or facility.
The “checklist” method is similar to the “what if?” method, except that a previously developed checklist is used which is specific to the operation, materials, process and equipment. This method is useful when conducting pre-startup reviews upon completion of initial construction or following major turnarounds or additions to the process unit. A combination of the “what if?” and “checklist” methods is often used when analysing units that are identical in construction, materials, equipment and process.
The hazard and operability (HAZOP) study method is commonly used in the chemical and petroleum industries. It involves a multi-disciplinary team, guided by an experienced leader. The team uses specific guide words, such as “no”, “increase”, “decrease” and “reverse”, which are systematically applied to identify the consequences of deviations from design intent for the processes, equipment and operations being analysed.
Fault tree/event tree analyses are similar, formal deductive techniques used to estimate the quantitative likelihood of an event occurring. Fault tree analysis works backward from a defined incident to identify and display the combination of operational errors and/ or equipment failures which were involved in the incident. Event tree analysis, which is the reverse of fault tree analysis, works forwards from specific events, or sequences of events, in order to pinpoint those that could result in hazards, and thereby calculate the likelihood of an event’s sequence occurring.
The failure mode and effects analysis method tabulates each process system or unit of equipment with its failure modes, the effect of each potential failure on the system or unit and how critical each failure could be to the integrity of the system. The failure modes are then ranked in importance to determine which is most likely to cause a serious incident.
No matter which method is used, all chemical process hazard analyses consider the following:
- process location, siting and hazards of the process
- identification of any prior incident or near miss with potential catastrophic consequences
- engineering and administrative controls applicable to the hazards
- interrelationships of controls and appropriate application of detection methodology to provide early warnings
- consequences of human factors, facility siting and failure of the controls
- consequences of safety and health effects on workers within areas of potential failure.
Management of change
Chemical process facilities should develop and implement programmes which provide for the revision of process safety information, procedures and practices as changes occur. Such programmes include a system of management authorization and written documentation for changes to materials, chemicals, technology, equipment, procedures, personnel and facilities that affect each process.
Management of change programmes in the chemical industry, for example, include the following areas:
- change of hydrocarbon process technology
- changes in facility, equipment or materials (e.g., catalysts or additives)
- management of change personnel and organizational and personnel changes
- temporary changes, variances and permanent changes
- enhancement of process safety knowledge, including:
- technical basis for proposed change
- impact of change on safety, health and environment
- modifications to operating procedures and safe work practices
- modifications required to other processes
- time required for the change
- authorization requirements for the proposed change
- updating documentation relating to process information, operating procedures and safety practices
- required training or education due to change
- management of subtle change (anything which is not replacement in kind)
- non-routine changes.
The management of change system includes informing employees involved in the process and maintenance and contractor personnel whose tasks would be affected by any changes of the changes and providing updated operating procedures, process safety information, safe work practices and training as needed, prior to the startup of the process or affected part of the process.
Chemical processing facilities must develop and provide operating instructions and detailed procedures to workers. Operating instructions should be regularly reviewed for completeness and accuracy (and updated or amended as changes occur) and cover the process unit’s operating limits, including the following three areas:
- consequences of deviation
- steps to avoid or correct deviation
- functions of safety systems related to operating limits.
Workers involved in the process have access to operating instructions covering the following areas:
- initial startup (startup after turnarounds, emergencies and temporary operations)
- normal startup (normal and temporary operations and normal shutdown)
- emergency operations and emergency shutdown
- conditions under which emergency shutdown is required and assignment of shutdown responsibilities to qualified operators
- non-routine work
- operator-process and operator-equipment interface
- administrative controls vs. automated controls.
Safe work practices
Chemical process facilities should implement hot-work and safe work permit and work order programmes to control work conducted in or near process areas. Supervisors, employees and contractor personnel must be familiar with the requirements of the various permit programmes, including permit issuance and expiration and appropriate safety, materials handling and fire protection and prevention measures.
The types of work included in typical chemical facility permit programmes include the following:
- hot work (welding, hot tapping, internal combustion engines, etc.)
- lockout/tagout of electrical, mechanical, pneumatic energy and pressure
- confined-space entry and use of inert gas
- venting, opening and cleaning process vessels, tanks, equipment and lines
- control of entry into process areas by non-assigned personnel.
Chemical facilities should develop and implement safe work practices to control potential hazards during process operations, covering the following areas of concern:
- properties and hazards of materials, catalysts and chemicals used in the process
- engineering, administrative and personal protection controls to prevent exposures
- measures to be taken in event of physical contact or exposure with hazardous chemical
- quality control of raw materials, catalysts and inventory control of hazardous chemicals
- safety and protection system (interlock, suppression, detection, etc.) functions
- special or unique hazards in the workplace.
Employee information and training
Chemical process facilities should use formal process safety training programmes to train and educate incumbent, reassigned and new supervisors and workers. The training provided for chemical process operating and maintenance supervisors and workers should cover the following areas:
- required skills, knowledge and qualifications of process employees
- selection and development of process related training programmes
- measuring and documenting employee performance and effectiveness
- design of process operating and maintenance procedures
- overview of process operations and process hazards
- availability and suitability of materials and spare parts for the processes in which they are to be used
- process start-up, operating, shut-down and emergency procedures
- safety and health hazards related to the process, catalysts and materials
- facility and process area safe work practices and procedures.
Contractors are often employed in chemical processing facilities. The facilities must institute procedures to assure that contractor personnel performing maintenance, repair, turnaround, major renovation or specialty work are fully aware of the hazards, materials, processes, operating and safety procedures and equipment in the area. Periodic evaluations of performance are made to assure that contractor personnel are trained, qualified, follow all safety rules and procedures and are informed and aware of the following:
- potential fire, explosion and toxic release hazards related to their work
- plant safety procedures and contractor safe work practices
- emergency plan and contractor personnel actions
- controls for contractor personnel entry, exit and presence in process areas.
Pre-startup safety reviews
Pre-startup process safety reviews are conducted in chemical plants prior to startup of new process facilities and introduction of new hazardous materials or chemicals into facilities, following a major turnaround and where facilities have had significant process modifications.
The pre-startup safety reviews assure the following have been accomplished:
- construction, materials and equipment are verified as in accordance with design criteria
- process systems and hardware, including computer control logic, have been inspected, tested and certified
- alarms and instruments are inspected, tested and certified
- relief and safety devices and signal systems are inspected, tested and certified
- fire protection and prevention systems are inspected, tested and certified
- safety, fire prevention and emergency response procedures are developed, reviewed, in place and are appropriate and adequate
- startup procedures are in place and proper actions have been taken
- a process hazard analysis has been performed and all recommendations addressed, implemented or resolved and actions documented
- all required initial and/ or refresher operator and maintenance personnel training, including emergency response, process hazards and health hazards, is completed
- all operating procedures (normal and upset), operating manuals, equipment procedures and maintenance procedures are completed and in place
- management of change requirements for new processes and modifications to existing processes have been met.
Design Quality Assurances
When new processes or major changes to existing processes are undertaken, a series of process safety design reviews are normally conducted before and during construction (prior to the pre-startup review). The design control review, conducted just before plans and specifications are issued as “final design drawings”, covers the following areas:
- plot plan, siting, spacing, electrical classification and drainage
- hazards analysis and process chemistry design
- project management requirements and qualifications
- process equipment and mechanical equipment design and integrity
- piping and instrument drawings
- reliability engineering, alarms, interlocks, reliefs and safety devices
- materials of construction and compatibility.
Another review is normally conducted just prior to the start of construction covering the following:
- demolition and excavation procedures
- control of raw materials
- control of construction personnel and equipment on facility and site
- fabrication, construction and installation procedures and inspection.
One or more reviews are usually conducted during the course of construction or modification to assure the following areas are in accordance with design specifications and facility requirements:
- materials of construction provided and used as specified
- proper assembly and welding techniques, inspections, verifications and certifications
- chemical and occupational health hazards considered during construction
- physical, mechanical and operational safety hazards considered during construction and facility permit and safety practices followed
- interim protective and emergency response systems provided and working.
Maintenance and mechanical integrity
Process facilities have programmes to maintain ongoing integrity of process-related equipment, including periodic inspection, testing, performance maintenance, corrective action and quality assurance. The programmes are intended to assure that mechanical integrity of equipment and materials is reviewed and certified and deficiencies corrected prior to startup, or provisions made for appropriate safety measures.
Mechanical integrity programmes cover the following equipment and systems:
- pressure vessels and storage tanks
- emergency shutdown and fire protection systems
- process safeguards such as relief and vent systems and devices, controls, interlocks, sensors and alarms
- pumps and piping systems (including components such as valves)
- quality assurance, materials of construction and reliability engineering
- maintenance and preventive maintenance programmes.
Mechanical integrity programmes also cover inspection and testing of maintenance materials, spare parts and equipment to assure proper installation and adequacy for the process application involved. The acceptance criteria and frequency of inspections and tests should conform with manufacturers’ recommendations, good engineering practices, regulatory requirements, industry practices, facility policies or prior experience.
Emergency preparedness and response programmes are developed to cover an entire process facility and to provide for hazard identification and assessment of potential process hazards. These programmes include training and educating employees and contractor employees in emergency notification, response and evacuation procedures.
A typical process facility emergency preparedness programme complies with applicable company and regulatory requirements and includes the following:
- distinctive employee and/ or community alarm or notification system
- preferred method of internal reporting of fires, spills, releases and emergencies
- requirements for reporting process-related incidents to appropriate government agencies
- emergency shutdown, evacuation, procedures to account for personnel, emergency escape procedures, vehicle and equipment removal and route assignments
- emergency response and rescue procedures, duties and capabilities including employees, public safety, contractors and mutual aid organizations
- procedures for handling small spills or releases of hazardous chemicals
- procedures for providing and safeguarding emergency power and utilities
- business continuation plans, personnel and equipment sources
- document and record preservation, site security, cleanup, salvage and restoration.
Periodic safety audits
Many process facilities use self-evaluation process safety management audits to measure facility performance and assure compliance with internal and external (regulatory, company and industry) process safety requirements. The two basic principles of conducting self evaluation audits are: gathering all of the relevant documentation covering process safety management requirements at a specific facility and determining the programme’s implementation and effectiveness by following up on their application in one or more selected processes. A report of the audit findings and recommendations is developed and facility management maintains documentation which notes how deficiencies had been corrected or mitigated, and if not, reasons why no corrective action had been taken.
Compliance audit programmes in hydrocarbon process facilities cover the following areas:
- establishment of goals, schedule and methods of verification of findings prior to the audit
- determination of the methodology (or format) to be used in conducting the audit, and develop appropriate checklists or audit report forms
- readiness to certify compliance with government, industry and company requirements
- assignment of knowledgeable audit teams (internal and/ or external expertise)
- prompt responses to all findings and recommendations and documentation of actions taken
- maintenance of a copy of at least the most recent compliance audit report on file.
Facility and process unit specific checklists are often developed for use when conducting process safety audits which cover the following items:
- orientation and process safety management programme overview
- preliminary walk-around through the refinery or gas processing facility
- process facility documentation review
- “prior incidents” and near misses (in the process facility or specific unit)
- determination and review of selected process units to be audited
- process unit construction (initial and subsequent modifications)
- process unit chemistry hazards (feedstocks, catalysts, process chemicals, etc.)
- process unit operations
- process unit controls, reliefs and safety systems
- process unit maintenance, repair, testing and inspection
- process unit-related training and employee involvement
- process facility management of change programme, implementation and effectiveness
- process fire protection and emergency notification and response procedures.
Because the objectives and scope of audits can vary, the compliance audit team should include at least one person knowledgeable in the process being audited, one person with applicable regulatory and standards expertise and other persons with the skills and qualifications necessary for conducting the audit. Management may decide to include one or more outside experts on the audit team due to lack of facility personnel or expertise, or because of regulatory requirements.
Process incident investigation
Process facilities have established programmes to thoroughly investigate and analyse process-related incidents and near misses, promptly address and resolve findings and recommendations and review the results with workers and contractors whose jobs are relevant to the incident findings. Incidents (or near misses) are thoroughly investigated as soon as possible by a team which includes at least one person knowledgeable in the process operation involved and others with appropriate knowledge and experience.
Standards and Regulations
Process facilities are subject to two distinct and separate forms of standards and regulations.
- External codes, standards and regulations applicable to the design, operation and protection of process facilities and employees typically include government regulations and association and industry standards and practices.
- Internal policies, guidelines and procedures, developed or adopted by the company or facility to complement external requirements and to cover processes which are distinct or unique, are reviewed periodically and changed when necessary, in accordance with the facility’s management of change system.
Process facility management should provide process information, without regard to possible trade secrets or confidentiality agreements, to persons who are:
- responsible for gathering and compiling process safety information
- conducting process hazard analyses and compliance audits
- developing maintenance, operating and safe work procedures
- involved in incident (near miss) investigations
- responsible for emergency planning and response.
Facilities typically require that persons to whom process information is made available enter into agreements not to disclose the information.