HAZOP what is it? Why do we need it?

 HAZOP what is it? Why do we need it?

 

A HAZOP may be a highly structured way of analysing all the items which will fail in a very complex plant like ours. It’s a Risk Assessment technique that has become the de-facto industry standard for all plants within the Oil & Gas, Chemical, pharmaceutical, power generation and even mining industries.

 Modern plants are complex, and there's the possibility that some things might not happen as expected. If things don't work as they're supposed to, it may lead to a disaster! And there may be so many things which will go wrong. We call them deviations. Now in HAZOP, we carefully examine every possible deviation and think about what  were to happen, if the deviation does happen. For each such deviation, we ask whether this can result in an unwanted occurence or an accident.  This might be a fire or explosion or tank that overflows, causing spillage of toxic material. Then, we predict of how to mitigate it and recommend ways to try and do it. It may well be an operator action or a security interlock or whatever is required. Then again a proper HAZOP Methodology takes care of it. Also, a trained HAZOP team can get it on pretty fast.

 The brief introduction of the HAZOP study.

1.     When HAZOP studies should be conducted?

2.     What are the prerequisites of this study?

3.     How a team of HAZOP study is made?

4.     What is that the worksheet?

5.     How the particular HAZOP study goes?

6.     and finally some do's and don'ts so that you'll be able to conduct this study very effectively

1. When HAZOP studies should be conducted? 

 HAZOP study may be conducted during the any stage of the method lifecycle but the best time to conduct this study would be when basic and detailed engineering is completed and therefore the P & IDs are ready for review. This study can be conducted during the any stage of the method life cycle but at that time the methodology and therefore the deliverable of this study would vary for instance this study may be conducted even in an operational plant but at that point the deliverables and methodology would should be slightly customized

2. What are the prerequisites of this study?

 • First requirement would be a detailed description of the process for which HaZop is to be carried out.

 • The second requirement would be P&ID or process and Instrumentation diagram it's also said piping and Instrumentation diagram

• The third thing which is very important in this study would be the details about process safeguards like alarms, trips & controls interlocks etc. this is often also called cause and effect diagram In some cases we may should refer some specific documents for instance layout or design documents for a particular requirement otherwise these three things would be sufficient enough to conduct a house of study

3. How a team of HAZOP study is made?

 The team of HAZOP study consists of

·        A HAZOP chairman : Has the role to sensible the discussion to guide the people and to conclude when the discussion is over so he's the in-charge of this whole study

·        The scribe writes this discussion in the tabulated form within the prescribed format of the worksheet

·         Participants are the team members has the role to administer inputs about the process as and when asked by the HAZOP chairman during the various stages of session The HAZOP the best team size would be five to 10 only if the team size is simply too big it should result in take an excessive amount of time waste of your time in deliberate discussions and it should result in take too much time to complete this study and at the identical time if the team size is simply too small for instance only two to a few people are conducting the study it should result in biased study counting on the views of only two to a few people

The team members should be from various department of the plant

• Process/Technical

• Production/Operation

 • Maintenance/Service

 • Safety • R&D etc.

4. The worksheet :

For conducting HAZOP study may be prepared either in Excel or world format.It may be customized as per the requirements Once can also use any software which is accessible within the market to conduct this study and plenty of worksheet formats are available . The worksheet would contain

·        Node

·        Description

·        Some process parameters and

·        some basic details

in the upper part of The worksheet columns content guide word/ parameter deviation/ causes consequences/ safeguards and eventually recommendations This is the best variety of HAZOP worksheet sometimes risk matrix is additionally added during this worksheet

5. How Hazop study is conducted?

1) First step is identification of Nodes: As the whole process is split into many P & ID’s and again this individual P and ID's needs to be subdivided into small sections called as nodes. allow us to understand what this Node is that the Node is that the small a part of the P & ID and it's identified supported design intention or the method unit operation to form it simple in input only those parts of the systems are included which are having the identical process unit operation functions so in a very P&ID when the method unit operation or the planning intention changes a separate node begins this is often what number nodes are identified on the P&ID it's a tricky part and required some experience and expertise After identifying the node the following step is to spot whole process deviations which are applicable and relevant for that exact node.

Now what is this deviation the deviation is the combination of two many phrases the one is guide word another one is process parameters there are several set of guide words like

·        high-

·        low

·        No more etc.

And there are several process parameters as well like

·        temperature

·        pressure

·        flow

·        level

·        conductivity

·        pH and likewise

So by combining this two different phrases that is guide word and process parameters identify various variations which are applicable for this Node so what could be the deviations

For example low pressure high flow,

 Low flow

 High level

Low level etc.

 So it can identify all the process deviations which are applicable for that particular node

Once node have identified then for each node identify various process deviations also now for each deviation identify what are the causes which will lead to this particular deviation for example we have identified high pressures for that particular node now we will identify what are the basic causes which will lead to occur high pressure and we will list all these causes one by one

The next step would be to identify the consequences for each process deviations. While identifying the consequences it will have to be a bit cautious that you will have to keep these two things in your mind when you identify the consequences due to process deviations what are they will tell you

1.      When you identify the consequences please consider that you should identify the consequences due to process deviation only not due to causes yes when you write the consequences it should be due to the deviation irrespective of the causes this is one thing you should consider.

2.      another thing when you write the consequences consider for a while that there is no safeguard available in the process at all, and in absence of safeguard what are the probable consequences that should be identified

3.     once the consequences are identified next would be to identify the available safeguard in the process setup now what are these safeguards it could be alarms, it could be trips, it could be controls, it could be SOPs it could be anything which should be capable to prevent the process deviation or the cause of the process deviation or it should be capable to save you from the consequences

4.     if that deviation occurs even after available d the safeguards that means this safeguard is not adequate to prevent you from this consequences you will have to go for the recommendations now what kind of recommendations you can give the recommendations should be such that there should be capable either to reduce your consequences or to reduce the causes or at all this would be capable to prevent the process deviations from occurrence itself there would be the right recommendations

And similarly you can cover all the nodes and you can cover all the p & IDs and that way you can do the HAZOP study for the entire process so this is the simplest and fundamental flow of various activities of a HAZOP.

 

6.           some do's and don'ts for conducting this study very effectively

 

·        Hazop is not a tool for design validation that means while  conducting in house study it is believed that design is adequate

·        Number two P and ID's are very important to conduct any hazop study so we should be very cautious when we use the P and ID's there should be updated and as built because in any house of study what doesn't appear in the P&ID is not considered to be actually existing in the site otherwise we will have to update our P & Id’s first before we conduct them as of study

·         the third thing when we identify the causes of the process deviation we should be cautious that we should not consider the failure of control logics and control system as the cause of our deviation this we should take care of and

·         the fourth thing when there are two or more similar systems similar trains then if we conduct HAZOP study for only one system it need not be repeated for the remaining systems which are quite identical in process

 

·        and some understanding about incorporating a risk  matrix in the  worksheet of HAZOP risk matrix comprises of three different columns that is

 

a.     severity

b.      probability or frequency

c.      and lastly the risk it could be a five by five matrix or four by four matrix

Now what is the use of risk matrix risk matrix helps us in prioritization of the risk matrix which is having three columns is incorporated after consequence after safeguard and in some cases

even after recommendations when a risk matrix follows by the consequences that means when the risk matrix is introduced immediately after the consequences it gives us how severe is the risk how big is the risk due to this consequence this will sensitize us to go for scrutinizing

Our safeguards when the risk matrix is incorporated after the safeguard it helps us in evaluating the efficacy of our safeguard whether they are capable to reduce risk or not and when the risk

matrix is incorporated after the recommendation it again gives us some insight about whether our recommendations are adequate enough to bring the risk level down or not so this is how actually risk matrix are incorporated at many places and that way it gives us help in prioritization of the risk so this is how actually risk matrix are incorporated at many places.