What is HAZOP?
A Hazard and Operability Analysis (HAZOP) is a risk management technique used to identify potential hazards and functional flaws in existing or planned plant systems. Its purpose is to reduce risk and ensure the safety of workers in plant environments.It is primarily used to study complex operational hazards and functions in chemical processing plants but is also used in nuclear, water, sewage, and treatment plants.
A HAZOP study is performed by an interdisciplinary team of experts including engineers, chemists, facilities managers and safety officers to identify procedural risks, process hazards, and design flaws.
This article covers: 1) how HAZOP is used as a risk assessment tool; 2) HAZOP examples and sample HAZOP study report; 3) software and tools to help streamline HAZOP reporting; and 4) free featured HAZOP template you can download and customize.
Click here to download your free HAZOP template.
HAZOP as a Risk Assessment Tool
HAZOP is based on the assumption that hazards happen because elements of design and operation can deviate from their original intention.
The HAZOP team discusses possible deviations and come up with different scenarios where the system or process could fail. The team can then propose recommendations for safeguards and improvements to lower the risk of identified hazards and operational failures from occurring.
A HAZOP study primarily assesses the following three parts of a plant function:
To assess the design’s capability to fulfill its intended function and identify its weaknesses e.g. the composition of the chemical batch reactor.
2. Physical environment
To assess the environment where the system or design will operate and ensure that it is ideal e.g. is there enough space for the chemical batch reactor to operate as intended?
To assess the engineered controls such as automation, sequence of steps, human interactions e.g. the steps in producing the target chemical concentration.
HAZOP Example Case Study
Here is an example of how a HAZOP study can be used by an expert team to assess the procedure involved in chemical production:
Chemical Mixing Plant
To produce a batch of 10% concentration HCl (Hydrochloric acid)
1. Reverse Osmosis (RO) water is added to the batch mixer via centrifugal pump
2. Additives are mixed with the RO water
3. A 33% solution of HCl is added to the mixture of RO water and additives, resulting in 10% concentration HCl
No RO water added.
Centrifugal pump loses priming or valve closed totally.
Solution will be highly concentrated.
Proper monitoring of the centrifugal pump (hydraulic pressure).
Hydraulic pressure gauge should be reviewed and maintained on a regular basis.
Review and do maintenance work on the hydraulic pressure gauge of the centrifugal pump.
Hypothetical Scenarios Using Guide Words
After identifying the objective and steps involved in the procedure, the HAZOP team will then explore different scenarios where the procedure could deviate from its intended function.
A HAZOP study encourages the use of “guide words” to help explore all potential deviations. Here is an example of how the team could use common guide words to explore deviations involving the input and mixture of RO water:
No or not (Design intent negated completely) - No RO water added
More (Quantitative increase) - RO water added is more than intended
Less (Quantitative decrease) - RO water added is less than intended
As well as (Qualitative modification/increase) - RO water mixed with UV water is added
Part of (Qualitative modification/decrease) - Tap water is added instead of RO water
Reverse (Logical opposite of design intent) - RO water is omitted from the mixture
Other than (Complete substitution) - UF water is used instead of RO water
Early (Relative to the clock time) - RO water is added too early
Late (Relative to the clock time) - RO water is added too late
Before (Relating to order or sequence) - RO water is added before the additives and 33% HCl are ready
After (Relating to order or sequence) - RO water is added after the additives and 33% HCl
In the first scenario where “No RO water is added” the team will deliberate and identify the possible causes, consequences, safeguards and ultimately provide a recommendation.
What is iAuditor and how can I use it for HAZOP Studies?
iAuditor is the world’s #1 inspection software and app. It can be used to streamline HAZOP data gathering and reporting. Complete and document your HAZOP study using your smartphone/ tablet while on-site with your expert team without returning to the office. Take unlimited photo evidence and annotations of design systems and deviations. Use voice dictation to save time and record detailed notes. All reports are securely saved in the cloud and easily accessible on online.
To help you get started, we have created a free HAZOP template that you can download and customize for your purpose.