What is a HAZOP?

HAZOP stands for a hazard and operability study and it allows a multidisciplinary team of engineers and operators  to identify and assess hazards and abnormal process conditions in an industrial process before an accident occurs. HAZOP studies have been instrumental in enabling the inherently safe design of facilities and allows us to better understand risk.

To better understand the goal of a HAZOP study, it's imperative to understand what the word risk truly means. There are two main components to risk, including the probability of a future event and it's consequence.

• Probability: the expression of uncertainty that a future event will occur.

• Consequence: an undesirable outcome that's defined by your project group or company. Without consequence, there is no risk.

A HAZOP study systematically identifies risks in a process through a creative and collaborative approach where shared perspectives help to inform high quality decisions about the design and operation of a facility. A comprehensive HAZOP that identifies all sources of risk is carried out by following the steps below.

Step 1: Identify the cause of the risk

To identify a risk, you must ask your team what can cause a hazardous event. This can be overwhelming since a process can have hundreds or even thousands of causes for hazards. The risk identification process can therefore be made more systematic by breaking up a process into separate nodes and thinking of specific process deviations for each node, including, but not limited to the following:

• No/low flow

• Misdirected flow

• High pressure

• Low level

• High temperature

By focusing your team's discussion on a specific node and deviation, the conversation becomes more productive.

Step 2: Describe the worse credible consequences without safeguards and assign a severity level

For each cause, the consequences can range from a fatality, a public relations disaster, a financial impact to fix damaged equipment or from a loss of production. Going into each HAZOP, the consequence categories should be defined and well understood by the team members. The four basic consequence categories are:

• Health and Safety

• Environmental

• Financial

• Reputation

Consequences are often different across the different categories since they are mutually exclusive. For example, pump damage due to cavitation will result in financial a loss, but it will have no environmental, health & safety or reputation consequences.

 Step 3: Assess the probability of the cause without safeguards

Based on the experience and perspectives of different operators and engineers, there may be differing opinions on the probability of the cause. Through discussion and perspective sharing, the HAZOP team must come to a consensus.

 Step 4: Evaluate the risk based on the severity and probability without any safeguards

To categorize your risk, use your company's risk matrix based on the probability and severity.

 Step 5: Asses the risk with safeguards

The goal is to reduce the risk of a cause by lowering its probability through the implementation of safeguards. Different examples include:

• Alarms with operator intervention

• Physical protection via pressure safety valves or rupture disks

• Automatic safety shutdowns

 Step 6: Make a decision to accept the risk or make a recommendation to further reduce the risk

By lowering the probability of a cause using a safeguard, the overall risk is also lowered. Refer to your risk matrix to determine if your risk level with safeguards is acceptable or not. A recommendation may be required to implement additional safeguards to reduce the risk further. Remember, all recommendations are required to have buy-in from both the operators and engineers, because there is no value in a recommendation without commitment to action.