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Control Systems HAZOP (CHAZOP)

Last updated: March 2, 2019

What Does Control Systems HAZOP (CHAZOP) Mean?

A Control Systems HAZOP (CHAZOP) is a HAZard and OPerability study of a control system.

Traditional HAZOPs evaluate the major safety hazards of a process or function involved in the operation of a plant, facility, piece of machinery, or other component of a work environment.

Safeopedia Explains Control Systems HAZOP (CHAZOP)

CHAZOPs are a part of the safety management process that focuses on the potential hazards associated with the operations of the control system exclusive from the function of the underlying processes that they manipulate and maintain.

CHAZOPs typically focus on two broad facets of the control system. First, they assess whether the control loops—the set of instruments that operate the functions being controlled—are adequate for the process that they are applied to. Second, they evaluate whether the control system is properly integrated with the underlying process and ensure that it does not act as a potential occupational hazard by causing unintended operational interference or obstruct the operation of another control system. A CHAZOP provides a measure of the safety risks that are associated with a particular control system, and as such, it provides a measure of the control system’s effectiveness.

A CHAZOP involves the study of a control system’s functions under all situations that the controls could potentially be used in. These situations include the startup of the machinery or process being controlled, as well as normal, irregular, turndown, and emergency operations. Of particular concern is the operational integrity of the control system during an emergency shutdown of the process that it is applied to.

CHAZOPs do not only identify hazards related to the integrity of the control system’s functions; they also identify hazards related to the operability of the control system. Therefore, the effectiveness of a control system’s instrument layout, the material used to explain its functions to relevant personnel, and the notifications and alarms associated with it, are all evaluated as part of a CHAZOP assessment.

Testing procedures for control systems are also evaluated to ensure that they effectively monitor and verify the integrity of the control system. CHAZOPs are a critical component of safety management in many industries in which effective controls of systems is vital to occupational and environmental safety, such as the operation of offshore oil and gas platforms.


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