Risk Assessment

Everything has risk.

You are at risk of an undesired outcome during everything you do – sitting at your desk, going for a walk, driving a car, flying in an aeroplane, going to work, etc.

Whether you recognise it or not, everything you do entails risk, usually for a reward. For example, driving your car might get you to the place you want to go, but you risk an accident or a breakdown when making the journey.

Usually, we make an unconscious decision of whether that the risk is worth the reward or not. If the risk is low, or the reward is high, we don’t usually have to think about it much. If the risk if high, or the reward is too low, we might stop and reconsider.

At work, Risk Assessment is more formalised. In the chemical industry, risks can be high. Doing a task wrongly, or an unanticipated event happening, can lead to injury and death of employees or the public, or damage to the environment, or serious loss of money or even reputation. Therefore all chemical engineering design and operation is assessed for the risk involved – what might go wrong, and what might be the consequences.

Hazards are the situations which can lead to loss. Once we have identified and quantified the hazards, we consider how likely they might lead to the undesired result. This involves assessing what has to happen which leads to the event, and what protection is in place to stop it happening. Nothing is perfect, so we need to quantify the overall likelihood of the undesired result happening. The frequency with which the identified loss is likely to occur is called the risk.

Then we need to assess whether the risk is considered tolerable against societal and legal requirements. If it is, generally the risk is acceptable providing it has been minimised. If it isn’t, the risk cannot legally be undertaken, and ways to avoid or further mitigate the risk are needed.

I’ve been involved with identification and assessment of risks on chemical plants for many years, and have used the major techniques involved in risk identification and assessment.

Identification tools include Hazard Study techniques, Failure and Effects Analysis, and Bow Tie analysis.

Risk assessment tools include Layers of Protection Analysis, Quantified Risk Assessment.

Hazard Study was developed by ICI (and independently by others). We identified 5 main stages:

  1. Early in process development – Hazard Study 1
  2. As the process is being defined – Hazard Study 2
  3. When the process & instrumentation diagrams and item designs have been completed – Hazard Study 3
  4. During construction and commissioning – Hazard Study 4
  5. After plant start-up and initial operation – Hazard Study 5

Of these Hazard Study 3 (also know as HazOp when operational issues are considered at the same time) is the most universally applied. These studies are done by a team of people, led by an independent Leader (also known as a Chairman). I have carried out this role many times.

Knowledgeable companies know that all these stages bring benefit and are well worth their cost. I have led Hazard Study 1 and 2 for a number of such companies. There is a separate page on this site about Hazard Studies.

Risk assessment for major risks is usually carried out outside Hazard Studies where they are usually identified. When risks have been identified and shown to be serious, then the assessment process needs to be recorded formally. If in future plant operation, experience is gained that indicates that the risk assessment was inaccurate, then the assessment can be revisited. Any new requirement becoming apparent to control the risk to an acceptable level can then be enacted.

For a paper on Risk Assessment, please follow this link: (to be inserted)