Remote HAZOP & LOPA Workshops

Hope you and your families are keeping safe and following the safety guidelines. During these tough times of COVID-19, face-to-face meetings have become a major challenge. To avoid any project delays and missed deadlines, many of my clients have asked me to host HAZOP and LOPA workshops via video conferencing while working from home.

I thought it would be helpful to share some tips for remote facilitation based on my experiences:

St 1 dust - Dangerous or not?

Hope all of you readers are doing well. It is the time of Diwali here in India and everywhere one can see people in the festival mood. Be careful and safe & have a wonderful Diwali.

Today I am trying to clear another misconception which I have come across while talking about St 1 dust. Many of our clients have told me that we are handling St 1 dust which is also the so-called "WEAK EXPLOSION" hence the risk is low. 

I always give them the example of Imperial Sugar Explosion in 2008 where a St 1 Sugar dust lead to 14 fatalities or Didion Milling Co. explosion in 2017 where St 1 grain dust was to blame for 5 fatalities, a dozen injuries and $1.8 million fine.

Combustible dusts are ranked into one of four classes i.e. St 0, St 1, St 2 and St 3. The level of explosion violence increases as we go from St 0 to St 3. The only dust that has zero risks of the explosion is a St 0 dust. However, all other dusts have an explosion hazard including the St 1 dust which can compromise containment on a piece of equipment, or blow out the walls of a building. Grains, Sugar, Fluor, etc. all fall in St class 1 dust.

Importance of Facility Siting

Is the control room in your facility located close to the tank farm? Is any occupied or functionally significant buildings close to a Maximum Credible Loss Scenario? Is your cylinder storage shed close to the drum filling area?

If you have wondered about this ever, then you should read this article to understand Facility Siting. Some incidents from the past have cleared the importance of facility siting in a plant.

The Flixborough explosion in 1974, where cyclohexane explosion shattered control room windows, collapsed its roof and demolished the brick-constructed main office block. Twenty­ eight people died, and thirty-six were injured in this accident out of which Eighteen of the fatalities were in the control room. Fortunately, over 200 fatalities were averted as the incident took place on Saturday when the main office block was unoccupied.

The Phillips disaster of 1989, where 40000 kg (85000 lbs) of a mixture of ethylene, isobutane, hexene and hydrogen was released and exploded. The second explosion involved BLEVEs of two isobutene storage tanks and the third explosion was the catastrophic failure of the ethylene plant reactor. The explosions killed 23 employees and injured 314.

ATEX - Compulsion, Option or Need of the hour?

Let us talk about another misconception which is rooting in the minds of some people.

If my company is not in Europe, why should we perform an ATEX risk assessment? It's not applicable in my country, why should I perform modification to the existing equipment and fittings?

All risk assessments should follow the simple hierarchical ‘Three Rules of ATEX/DSEAR’ approach:

1. Do not have a flammable atmosphere, but if you do...
2. Do not ignite it, but if you do…
3. Do not hurt anyone.

ATEX intentions are simply to provide a coherent focus for controlling risks from:

1. Substances with flammable, explosive and oxidising properties. ATEX also covers Corrosives and compressed gases.
2. Substances which can create potentially explosive atmospheres
3. Controlling work activities involving other substances that could create a fire or an explosion

If you are in a country where ATEX/ DSEAR is not applicable, then you can consider this as a good engineering practice that you are reviewing your plants' operations to establish a Basis of Safety for each and every operation.

Dust Explosion in Equalizer 2 - Have you seen it yet?

I am sure if you are a movie enthusiast, you would have already seen Equalizer 2. 

Did you happen to notice Denzel Washington creating a flammable dust cloud? 

The movie market was too saturated with Gas Explosions, so here comes a new type of explosion. The director took full advantage of the shot inside a bakery. 

Process Safety Strategy - Chemical Reaction Hazard

It has been some time since I wrote my last post. I was on leave for my marriage. I have returned to the office now and I am back with another post on Chemical Reaction Hazards. Many times, I have come across people asking us what steps should be followed for identifying and mitigating the chemical reaction hazards. Today we will be talking on the same.

First, of all, I would like to thank Fauske & Associates LLC (FAI) for their continuous support and for publishing my last blog post on their website. If you have missed the same, you can access it by clicking on the link below

https://www.fauske.com/blog/should-set-point-for-pressure-relieving-device-be-equivalent-to-design-pressure

As per the research conducted by Dr Phil Nolan (South Bank University, UK) and Dr John Barton (UK Health and Safety Executive) and graduate students based on data analysis, the following four gaps have contributed equally i.e. 25% each to thermal runaway reactions leading to multiple incidents in past:

1. Lack of proper understanding of the thermochemistry (heat of reaction) and chemistry (balanced chemical equation)
2. Insufficient engineering design for reactor heat transfer system
3. Inadequate control and safety back-up systems including emergency relief systems, process vent, and other engineering controls
4. Poorly written batch procedures and insufficient operator training.

Concept Sciences Inc. Explosion

Hence, it is imperative to develop a process safety strategy to address these four gaps. A process safety strategy should include the following:

Should set point for Pressure Relieving Device be equivalent to Design Pressure?

Hope all of you are doing well. Today's topic is focusing on the general practice sometimes followed in industry related to the set point of Pressure Relief Devices of process equipment. Many times during PHA, I have come across a general philosophy of keeping the set point of the reactor's pressure relieving devices equivalent to its design pressure. This might be adequate for a non-reactive system. But the question is, is it adequate for a reactive system?

Here, the reactive system is one where there are hazards due to a chemical reaction, including the possibility of decomposition or polymerization or some side reaction, etc. We know based on normal kinetics that the rate of reaction is directly proportional to the temperature which in turn is proportional to pressure. In simple terms, it is said that the rate of a chemical reaction doubles with every 10 deg C rise in the reaction temperature. Hence it can be said that:

Higher set pressure leads to a correspondingly higher "set" temperature (i.e. the relieving temperature).  This, in turn, leads to a higher rate of reaction which results in higher self-heating or higher temperature rise rate (dT/dt i.e. deg C/min) and a higher pressure generation rate (dP/dt i.e. bar/min). This is very important because for a chemically reactive system the required pressure relief area depends directly on the self-heating and pressure rise rates at the relief conditions.

Dust Flash Fire in a hostel - Who said that they don't see a dust explosion at home?

Happy New Year 2019 to all of you!

The Dust Flash Fire incident in Baptist University of Hong Kong has left all of us in shock with immense sadness and a heavy heart. Birthday party went wrong and ended in burning and injuring 12 students.

Five students were having a collective birthday party and were singing around the birthday cake. Someone in the group started throwing flour around, which probably got ignited by the burning candle and the flames reached the ceiling height leaving students with first and second degree burns on arms, legs and face.

Insights of a Dust Hazard Assessment (DHA)

Thank you all for your continuing support on my blog posts. Keep sharing with your friends and colleagues.

We have discussed a lot about dust explosion hazards and the risk to plant. The next question which stands is "How to carry out Dust Hazard Assessment (DHA)?" The intent of this post is for making you aware of how you can carry out a dust hazard assessment or if you have a third party doing it for you, then how to review the DHA report?

Risk Ranking:Essence of any Hazard Analysis

Recently, I was giving training on HAZOP and I got a question "Why do you say that our HAZOP is incomplete without risk ranking? We are doing the study since so long and no auditor or authorities have ever questioned us for the same." 

So this question has made me think about the situation Process Safety is facing. We know that oil & gas has developed more than other sectors including FMCG, Pharmaceutical, Chemical (Bulk & Speciality), etc. with far better standards for performing safety studies including PHAs. So, here I am writing this post to share the importance of risk ranking in any hazard analysis technique.