A process hazard analysis (PHA) (or process hazard evaluation) is an exercise for the identification of hazards of a

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management * Business process, activities that produce a specific s ...

facility and the qualitative or semi-quantitative assessment of the associated

risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environ ...

. A PHA provides information intended to assist managers and employees in making decisions for improving safety and reducing the consequences of unwanted or unplanned releases of

hazardous material Dangerous goods are substances that are a risk to health, safety, property or the Natural environment, environment during transport. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials (syll ...

s. A PHA is directed toward analyzing potential causes and consequences of fires, explosions, releases of toxic or flammable chemicals and major spills of hazardous chemicals, and it focuses on equipment, instrumentation, utilities, human actions, and external factors that might impact the process. It is one of the elements of

OSHA The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...

's program for

Process Safety Management Process safety management (PSM) is a practice to manage business operations critical to process safety. It can be implemented using the established OSHA scheme or others made available by the EPA, AIChE's Center for Chemical Process Safety, or ...

. There are several methodologies that can be used to conduct a PHA, including

checklists A checklist is a type of job aid used in repetitive tasks to reduce failure by compensating for potential limits of human memory and attention. Checklists are used both to ensure that safety-critical system preparations are carried out completely ...

hazard identification A hazard analysis is one of many methods that may be used to assess risk. At its core, the process entails describing a system object (such as a person or machine) that intends to conduct some activity. During the performance of that activity, a ...

(HAZID) reviews, what-if reviews and

SWIFT Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIF ...

, hazard and operability studies (HAZOP), failure mode and effect analysis (FMEA), etc. PHA methods are qualitative or, at best, semi-quantitative in nature. A simple element of risk quantification is often introduced in the form of a

risk matrix A risk matrix is a matrix that is used during risk assessment to define the level of risk by considering the category of likelihood (often confused with one of its possible quantitative metrics, i.e. the probability) against the category of cons ...

, as in preliminary hazard analysis (PreHA). The selection of the methodology to be used depends on a number of factors, including the complexity of the process, the length of time a process has been in operation and if a PHA has been conducted on the process before, and if the process is unique, or industrially common. Quantitative methods for risk assessment, such as layer-of-protection analysis (LOPA) or

fault tree analysis Fault tree analysis (FTA) is a type of failure analysis in which an undesired state of a system is examined. This analysis method is mainly used in safety engineering and reliability engineering to understand how systems can fail, to identify the ...

(FTA) may be used after a PHA, if the PHA team could not reach a risk decision for a given scenario. In the United States, the use of PHAs is mandated as one of the elements of the

Occupational Safety and Health Administration The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...

(OSHA)'

process safety management Process safety management (PSM) is a practice to manage business operations critical to process safety. It can be implemented using the established OSHA scheme or others made available by the EPA, AIChE's Center for Chemical Process Safety, or ...

regulation for the identification of risks involved in the

design A design is the concept or proposal for an object, process, or system. The word ''design'' refers to something that is or has been intentionally created by a thinking agent, and is sometimes used to refer to the inherent nature of something ...

, operation, and modification of processes that handle highly hazardous chemicals.

See also

References

Further reading