HAZOP Guidewords

HAZOP Guide words are one of the unique things about the Hazard and Operability technique. There are a set of commonly used words that can be used to generate multiple abnormal scenarios, which we call as "deviations" in the technique. Every such word coupled with a particular parameter, then represents a unique deviation. For example to study a deviation of a flow lesser than normal, we use the guideword less or lesser than, coupled with a parameter flow. These two combined give us the deviated scenario of less than normal flow.

This less than normal flow is then analyzed thoroghly by the HAZOP team members to brainstorm if it will lead to nay dangerous consequences. If such is indeed the case, then the team's scribe (also known as HAZOP Scribe) writes down this as a dangerous consequence in the worksheet. Generally if the plant's design is sufficiently robust, then such deviated conditions are taken care of by the basic process design such as for example, having a flow switch that trips the pumping if the flow is low (just an example). If not, then the team suggests this, which goes into the worksheet as a recommendation. There may be of course other ways in which these parameters can be recognized and safeguards built, to correct for the effects of such abnormal conditions happening.

But then we are deviating from the topic- we are here to learn about guide words, right? You may be wondering how can somebody think of all the guidewords that are needed? Well, you can simply write down all of them at the beginning itself, or enter them into your HAZOP Worksheet before you begin the study. If you are using a documenting HAZOP Software, then the guidewords are already in the database and will be used to generate the different scenario conditions.

What are some common examples of such guide words? Here is a snippet of such a list below:
LESS
MORE
OTHER THAN
REVERSE
NO
EARLY
LATE

Now if you couple them with a parameter such as FLOW, you get the deviations as below:
LESS FLOW
MORE FLOW
OTHER THAN FLOW (checks if the fluid has been substituted by another one)
REVERSE FLOW (direction of flow has changed)
NO FLOW (empty)

The below ones can be used for batch processes, where sequencing is of importance.
EARLY FLOW (fluid starts flowing earlier than what is designed)
LATE FLOW (starts flowing later than designed).

If you need a more comprehensive training in this technique, then simply go to the HAZOP training course here. You can get access to an excellent e-learning course and what's more, also earn a certificate and an electronic badge, if you pass the associated exam.

Human Factors in HAZOP & other risk assessment techniques

How important are human factors when carrying out risk assessment studies such as HAZOP, LOPA and other techniques? Very much important it turns out, although until now most practitioners did not include this factor in their risk assessment studies. But of course we know that accidents can and do happen due to human error. Is there a policy guideline for this in place? Yes, it turns out that there is, in fact it was released a long time ago.
The UK Health and Safety Executive reportedly is mulling to include a "human" factor in risk assessment of major hazard facilities (COMAH). They have released a policy roadmap that details this here.
For example if the Risk assessmnet of a major hazard facility shows that it is essential to carry out some maintenance tasks regularly to reduce the risks, then a human factors analysis should be done to find out if
a) whether the task itself could be skipped?
b) whether any alarms can be raised if this is skipped due to error, negligence or simply laziness?
c) whether an incompetent performance of this task could result in an accident?
Very valid questions and a long way to go to analyze all the myriad things that humans can and many times actually do wrong!
So in your next HAZOP review one of the deviations should be "operator did not perform the task at all OR he did not perform the task correctly". This condition has not been included in any HAZOP formats or software to the best of our knowledge but should be and will, in the near future.
If you would like to know more about this aspect, you can check out the Abhisam course here.

HAZOP Video-Training Course

Here's a great video about HAZOP training that is on Youtube. See it below for yourself. The video basically tells you about HAZOP and how you can learn it in the comfort of your own home or office. Attending classroom trainings can be a pain these days, as you will have to spare time as well as a great deal of money AND be away from work to attend it. At the end of the day you may forget everything!

So here's an alternate way to learn all about the HAZOP process and also get certified in HAZOP! Note that it is not just a HAZOP ppt, it is a complete course.

HAZOP Study

HAZOP Study- What is HAZOP?
(Note: To learn about HAZOP Study in detail and to get certified as a competent person, please download or enroll online in the Abhisam HAZOP training course)



HAZOP is an acronym which is short for Hazard and Operability study and it was first introduced many years ago by ICI, a multinational chemicals company, based out of the UK. ICI no longer exists today as ICI (various parts have been taken over by companies such as Huntsman and AkzoNobel), but the HAZOP study technique that they pioneered, continues to grow in importance.
HAZOP is a risk assessment technique, used mainly in the chemical  and process industries such as oil and gas, refining, petrochemical, heavy chemicals, pharmaceutical and power generation as well as industries such as mining too. HAZOP is one technique out of a group of risk assessment techniques that form part of PHA (Process Hazard Analysis) . Other techniques in PHA are FMEA (Failure Modes and Effects Analysis), LOPA (Layer of Protection Analysis), HAZID (Hazard Identification), What-If analysis and of course checklists. HAZOP is more subjective rather than quantitative.

The HAZOP technique is  designed to identify the intentions and deviations of a particular operation, called a node. For example, a node may be a section of a plant that pumps liquid from a storage tank to a reactor some distance away. Then in this node, the original intention is identified (transporting liquid from the storage tank to the reactor) and then all possible deviations are analyzed in detail. Some of these deviations may result in accidents (for example if there is a reverse flow of liquid from the reactor to the tank). This process (the HAZOP process) is known as a HAZOP Study.

You may now appreciate that a HAZOP study should be done only by skilled personnel. If an unskilled or untrained person carries out a HAZOP (using the best software or no software), the chances of doing a bad HAZOP increase manifold. Doing a bad HAZOP is worse than doing no HAZOP at all because a bad HAZOP lulls people into a false sense of security, that their HAZOP study is complete (and the recommendations are implemented and the plant is safe and everybody lived happily ever after) when actually the opposite is true.

HAZOP Process

HAZOP Process-what does it mean? The word HAZOP is an acronym for HAZard and Operability Study, which is a Risk Assessment technique used extensively in the process industries (such as Oil and Gas, Chemicals, Petrochemicals, Power, Pharma and others). The HAZOP Process is a structured method that is a part of a PHA (Process Hazard Analysis), in which one examines a small part of a plant or facility (called as a Node) using a set of Guide Words that seek to examine all the permutations and combinations possible in a particular plant operation. For example, if one is analyzing the flow of a liquid from say a day tank (lets call it Tank A) to another tank (say Tank B) then there are several things that can go wrong with this simple process, such as Low Flow, Reverse Flow, No Flow and so on. These guide words (Low, Reverse, No) are combined with a parameter (such as Flow) to generate possibilities of what could go wrong in the operation.
Then each combination gives us an opportunity to think what can happen. For example if the normal operation of the process is to transfer liquid from Tank A to Tank B, then Reverse Flow will be from Tank B to Tank A. Will this cause any problems? We then list all these problems under the heading of "consequences" and for each consequence we can think of a protective method by which this consequence can be avoided. Thus if we determine that reverse flow will have dangerous consequences, then we can prevent it by having a Non Return Valve in the line that connects Tank A to Tank B.
Thus each such condition will be evaluated for consequences and protective measures designed. If we do this diligently for the entire plant, we will have a much safer operation!
If you wish to know more about this HAZOP Process, you can download an excellent e-learning course here.