What is a HAZOP Analysis?


A HAZOP (Hazard and Operability) is a structured and systematic qualitative -not quantitative- study that examines processes and operations (for instance, activities that people will carry out) to identify and assess problems that may pose risks to one's personnel or equipment (assets).

A HAZOP should be carried out in the early stages of a development. Typically, via forming part of the final verification when the detailed design of the solution will be completed. A HAZOP can also be performed on an existing facility to identify improvement opportunities to reduce risk and operability issues.


The more general objective of a HAZOP is, of course, to improve the operations carried out on a system, reducing its associated risks, thus improving its efficiency. It is also important to highlight, according to our experience, that general awareness is gained among the parties involved, generating an interesting thread between the design teams and the teams that use or maintain the designed systems.

On a second level of detail, a HAZOP allows the following:

  • Identifying all deviationsfrom the initial way a system is intended to work and be used, their causes and all associated hazards and operability problems.
  • Analysing all the operating modes, systematically: in normal operation, in the process of starting up, in routine shutdowns, in emergency stops, degraded operating or special modes.
  • Decide whether actions are required to control the identified hazards and/or operability problems and, if so, identify ways in which the problems can be solved.
  • Identify cases in which a "definitive" decision cannot be made, designing an action plan that will allow the information required for a correct evaluation to be obtained.
  • To ensure a correct follow-up of the actions decided upon.
  • Inform the operator or technical personnel of the dangers and problems associated with the processes executed.


  • [V] By using a procedure with "names and surnames" it is possible to carry out a systematic method without leaving out important aspects to be analysed. The work team that analyses the operations has an independent character (they are neither users nor executors of these operations), the results obtained are recorded , etc.
  • [V]It seeks to be a multidisciplinary studyusing the point of view of different parties that are involved in a system.
  • [V] It is a strategy to analyse and mitigate the human factor , which is increasingly considered relevant to study and be taken into account.
  • [V] The HAZOP not only identifies, but it also proposes solutions to the identified problems.
  • [D] As a team-based procedure, if these are not efficient, they can become a waste of time. It is important to note that different profiles involved must be included: the project manager for the system in question, the system designer engineer, the process engineer, the safety engineer, the maintenance engineer, and the commissioning engineer. Apart from the person responsible for the activity of HAZOP , who will manage the whole process of analysis and decision making.
  • [D] According to our experience, the "personal ego" of some designers can make them defend solutions (products, systems and their associated processes), which are left without the possibility of analysis with inherent risks.

To carry out a HAZOP, we will start from the design starting information, where the procedure that is carried out is defined, that is, the starting point where it is identified as the process is expected to work. From a qualitative point of view, on many occasions, HAZOP defines these procedures since they are not described by a lax design process. From the initial starting point, DEVIATIONS in which a process can deviate from its initial design intention, analysing possible reasons or causes (the reason why) and the consequences of the deviations. For mature and robust designs, during the analysis we will find the SAFEGUARDS, i.e. parts of the system or installation, which have already been introduced to reduce the frequency of occurrence of the deviation or to mitigate its consequence. Having analysed the ELEMENTS -> PROCESSES -> DEVIATIONS -> CAUSES -> CONSEQUENCES -> SAVINGS , we will be able to define the action plan to be carried out to mitigate (or not) the identified risk.

When does a HAZOP work?

According to our experience, a HAZOP works and is useful when these 4 points are met. We recommend taking them into account in order to obtain profitable and satisfactory results:

  1. A starting information as rigorous as possible , which in many occasions, implies to start generating this starting information.
  2. A responsible for the process of development of the HAZOP with experience and knowledge.
  3. A professional team with experience , being multidisciplinary , open-minded, focused on the search for deviations and solutions, and adhering to the HAZOP process and the instructions of the person in charge of HAZOP.
  4. Ability of the team to maintain proportionality and common sense, especially in the phase of assessing severity and possible consequences.

At Leedeo Engineering, we are specialists in the development of RAMS Railway projects, applying CENELEC standards EN 50126, EN 50129, EN 50128, EU Implementation Regulation 402/2013 with the application of the Common Safety Methods CSM-RA, supporting any level required to RAM and Safety tasks, in the development and certification of safety products and applications.

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