Recent incidents in Indian Industry creating turmoil

Yesterday's fire and explosion incident in Yashashvi Rasayan has made me ponder upon the prevention and protection measures taken by the manufacturing plants.

The incident has been said to be in the tank farm area. As per the initial reports, the fire in the tank farm has lead to an explosion of solvent storage tank/ tanks. In multiple images, damaged tanks, hydrogen trolley and multiple other plant units could be seen in the near vicinity of the tank. The other images of the incident are quite disturbing with charred bodies lying on the ground. There is a disturbing video of a charred man asking for help outside the plant that is being circulated in social media. The root cause of the incident still needs to be confirmed by the authorities. 

This incident combined with Vizag Styrene release and Tarapur surfactant factory explosion has put multiple questions in my mind. 

• Do you think that the understanding of Indian industry to process safety has improved? Do you think enough measures are taken in a plant to prevent unsafe acts and unsafe conditions? 

• Do you think that management of your plant or the neighbouring plant is seriously implementing measures and filling gaps identified in audits and PHA studies? 

• Do you think that government authorities are seriously making proactive reviews of the sites? 

• Do you think our laws and regulations related to industries are stringent enough to make the industries realise that they have more to lose in an accident than to gain in the normal operation of the plant? 

In my opinion, some industries have a better understanding of the importance of process safety in their plant and they implement preventive and protective measures as well. But several of them lack resources and knowledge related to process safety and how to prevent unsafe conditions and acts in their plants. They are still limited to hard hat and steel toe shoes safety which is important, but there is so much more to safety.

Many do not understand the importance of a good PHA study and how it can help in preventing and safeguarding against incidents. For example, I have worked with companies representatives who have asked me "why are you taking a scenario of external fire in a tank farm as I have enough fire monitors and hydrant points available in plant to fight such a scenario?" or "Why are you recommending a dump tank for a PSV release as I have high-pressure alarm and interlocks for my vessel?"

Although we have many existing guidelines, laws and regulations. Also, frequent inspections keep on going on in our plants. But it is high time to bend our perspective towards Process Safety along with general safety. It is high time that we understand and focus on topics like chemical reaction and thermal runaway hazards, facility siting, the importance of Management of Change and quality PHAs, risk of Dust Explosion, risk of fire/ explosion due to electrostatic discharges, the importance of QRA (Quantitative Risk Assessment) and LOPA (Layer of Protection Analysis) studies for the major accident hazard scenarios, the importance of Process Safety Management (PSM), etc.

These incidents leave us and our families devastated and in turmoil. We need to learn from these incidents and improve our facilities. At the end of the day, we all should return to our families safe and sound.

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.

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. 

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?

Are you aware of the Dust Explosion Hazards in your facility?

I have written some blogs answering questions which I have received during training sessions or by email from our clients. Today I am sharing my experience related to the awareness level of manufacturing companies related to Dust Explosion. 

I made a recent visit as part of a non-profitable project to one of the most widely used Detergent and soap brands in India. As soon as I reached the gate of the plant, it was clear that I have entered a plant which hasn't been too serious about safe operations or safety of employees, as I could see the workers moving without any footwear leaving their feet marks in the raw materials spilled on the floor. There was so much dust and detergent in the air that I could taste detergent on my tongue till the next day of my visit.

Housekeeping and Secondary Dust Explosions

Thanks for such brilliant response to my past blog on Relief Sizing. It really feels satisfying when it gives food for thought to people about their own plants. It is a much wider subject, hence all of us can hold different opinions on what is already there in terms of regulations and what is practically being done at the grass root level. In the end, my objective is simple and that is to make the community aware of some process safety aspects which can help them make their operations safer.

For this blog, I will be discussing the importance of housekeeping to prevent Dust Explosion or should I say Secondary Dust Explosions.

How many companies out there still utilise compressed air for cleaning of equipment surfaces and to blow off the settled dust from surface/ floor/ clothing?

How many of them still dry broom dust settled on the shop floor?

How many of you still don't know that the powder which is settled on equipment surface, shop floor, electrical fitting, etc., is combustible in nature and can result in fire/ explosion hazard in the plant?

How many of your plants have false ceilings and that hidden area is not being reviewed for any powder accumulation?

How many of you still use non-rated vacuum cleaners in plant areas to remove the spilt dust?

Partial Inerting - A Cost Efficient weapon against Dust Explosion

Hey everybody, hope you are enjoying my blog and finding the information useful in your field of work. Today we are talking about a topic which is rather less explored and understood in many industries as of now i.e. "Partial Inerting".

Let's start first with understanding Inerting. Inerting is defined as the replacement of "oxidant" in a system by a non-reactive, non-flammable gas, to make the atmosphere within the system unable to propagate flame. Inerting may be achieved by using a non-flammable gas, which will neither react with the fuel nor with the oxidant. There are many gases used for inerting such as Nitrogen, Carbon Dioxide, Flue Gases, Noble Gases (Argon, Helium), etc.

P.S: Some material may react with these inert gases under some conditions. Hence, correct selection of gases is critical.

Now let's discuss the concept of PARTIAL INERTING to prevent dust fire and explosion. Partial Inerting means dilution of oxidising atmosphere with an inert gas but not up to the extent of LOC i.e. oxidant concentration lies between LOC and atmospheric concentrations. In other words, for partial inerting, the oxidising atmosphere (most often air) in which the explosible dust is dispersed is mixed with a fraction of inert gas (e.g. nitrogen) considerably smaller than that required for complete inerting (i.e. below LOC). 

Explosion Severity Test and St Class : Modified Hartmann vs 20 Litre (St 0H/1H/2H vs St 1/2/3)

Hope you have enjoyed the posts till now. The response has been overwhelming with the number of emails regarding the queries and some regarding the requests for upcoming posts. I would again like to request to all of you that, I am always in search of some good topics related to Process Safety, Dust Explosion, Electrostatic Hazards, Hazardous Area Classification or any other process safety-related concern. Do send in your queries and requests here in comments or on himanshuchichra@gmail.com. Let's continue with the present discussion topic now.

It has recently been told to me by one of the clients’ that their explosion severity test states the results as St 1H in place of St 1/2/3. His question was simply that should I go ahead and provide an explosion vent corresponding to St 1? Now, this is a tricky one.

Dust Explosion - Which Powder should be tested? Can I use the properties from internet for my powder?

"Nothing has happened in my facility and it has been running for 20 years"; "My powder cannot explode, we use this at home commonly"; "Are you still wondering if you have combustible dust?" Just because nothing has happened yet doesn't mean it's not about to.

This week I received an interesting query about which powder should be tested. Interestingly, there was an additional statement attached to the question, "I have searched over the Internet and have found my powder explosive properties. Can I use these properties for my site assessment?"

Some of the powders which can explode include food materials (including sugar, spice, starch, flour, etc.), plastics, wood, paper, rubber, pesticides, pharmaceuticals, chemicals, coal, metals, etc.

According to OSHA, "any combustible material can burn rapidly when in a finely divided form. If such a dust is suspended in air in the right concentration, under certain conditions, it can become explosible. Even materials that do not burn in larger pieces, given the proper conditions, can be explosible in dust form."

For liquids and gases, flammability data are well understood & usually established and available at least under atmospheric pressure and normal temperature conditions. However, for powders/ dusts is not available and is dependent on multiple parameters such as particle size, moisture content and also on particle shape/ morphology.

Usually, the properties which shall be tested for each of the unit operations differ depending on their requirement for that unit operation. We will pick this topic in our next blog.

Now let us look at each of these parameters:

• Particle Size: It has to be noted that explosion properties of a powder usually worsen with decrease in particle size. This means that finer the particle size easier it will be to burn and consequences can be worse as well. Powder used in industries is a distribution of smaller and larger particles. Whenever it disperses, the larger particles will fall to the ground because of more weight, however, the fines will remain suspended in the air forming a dust cloud. As per IEC standards, a particle size of less than 63 microns is used for conducting various tests. As per standard thumb rule, a particle size of more than 500 microns is not considered to be capable of propagating dust explosion.

• Moisture Content: First and foremost impact of using water is that it suppresses the dust cloud formation. Also, increased moisture content act as an inert and makes the ignition of powder more difficult and also impacts explosive properties of a powder. As per IEC standards, the powder is dried to moisture content of less than 10% before testing.

• Particle Shape and Morphology: Even with a change in particle shape and morphology from crystalline to amorphous, the material properties change significantly.

Hence the answer to the question is, one should test the finest and driest sample being handled on their site. Don’t depend on the Internet properties as one doesn't know what condition it has been tested for, what was the particle shape, size, etc.

Also, it is imperative to test the powder if a vendor is changed or if the manufacturing process is modified or if physical characteristics of the final material change or if any material has a combination of various particle sizes.

This will give you worst possible characteristics of the powder based on which assessment should be carried out and measures should be provided.

Do not forget to like and share with your team & friends. You can always drop an email on himanshuchichra@gmail.com regarding your query or a future blog post.

Shortcomings of Explosion Venting Design

Hey guys, let me thank you all for making this blog a success and for sharing your thoughts. I hope you are gaining some useful insights for the queries which arise in your mind related to process safety. I can really add more value if, you drop in other queries and I probably can select some of them for the upcoming blog posts.

Now let’s discuss Dust Explosion Venting, which I guess many of you out there struggle with. 

For each dust, maximum overpressure and rate of pressure rise can be measured in an explosion severity test carried out using a 20-Litre Sphere, where a controlled explosion is carried out and the resultant pressure is measured in order to determine the (dP/dt)max and Pmax. This (dP/dt)max is then used to find Kst value utilising cubic law. 

Any vendor who is designing explosion vents will ask for at least Kst value of the powder handled, size of equipment and equipment drawing.

Next question which people ask is "What to do if we handle multiple powders in a single equipment?"

The answer is simple, understand the worst Kst dust being handled in your equipment and design your system according to that. 
Since Minimum Explosible Concentration (MEC or what is called as LEL of dust) is usually as low as 10-30 g/m3 as well for powders. So even if you are only expecting a small amount of a dust inside the equipment, its wise to consider the worst case Kst of the powder. 

Then the question comes “Is my system safe now I have provided explosion venting?”

The answer still depends on whether you have isolated the other systems connected to the equipment or not. I know this sounds alien to many of you, but its very simple to understand. Any pressure will be diverted to the easiest path with least resistance possible. 
On one side we provide explosion vent to the equipment which will burst open at a certain pressure (or a small resistance), however, the connected system is the easiest path for the pressure wave to travel (due to negligible resistance). So the answer is your system is safe only if you prevent the propagation of blast wave to the connected system by utilisation of EXPLOSION ISOLATION (can be active or passive, will be discussing on these in future) designed adequately to hold. 

The next question which arises here is that “Is my plant safe now since I have provided explosion vent and isolated other systems as well?”

The answer is dependent on where the explosion is being relieved. The relieved blast wave with flames or flameless (depends on the type of explosion vent used) has to go to a safe location such that it doesn’t hurt people and plant. I have seen plants, where explosion vent is facing a wall or two explosion vents are facing each other or an explosion vent is reliving on plant’s internal busy pathway. This can escalate the event and might lead to damage to people, equipment and property.

So there is the recipe for explosion protection using explosion venting. The ingredients involve Powder Kst, adequately sized explosion vent (designed as per Kst) relieving to a safe location, Explosion Isolation device to prevent propagation.

Hope this helps you guys in understanding the concept of explosion venting.

Do like, share, comment and follow the blog because this is just the beginning. You can always follow using email to receive updates on any new post.

And remember, all of you can drop me an email on himanshuchichra@gmail.com if you would like me to write up on any specific aspect. 

Can Electrostatic Discharge (ESD) from Non-Conductive Bags act as an Ignition Source?

Hope you are enjoying the posts and able to gain some insights from the blog.

Now for this week blog, I am touching on a more sensitive question, which people have asked me in almost all Electrostatic Hazard Seminars. "Can Non-Conductive Bag act as an ignition source?"

A non-conductive bag, being an insulator can act as a source of Brush Discharge which has approximate energy of up to 3-4 mJ associated with it. Depending on the type of flammable atmosphere, brush discharge from the non-conductive bag may/ may not act as an ignition source.

Based on the equivalent energy of brush discharges, it must be assumed that most potentially explosive gas/air mixtures, solvent vapor/air mixtures and hybrid mixtures (vapor/gas and dust with air) can be ignited by brush discharges.

Are there two types of Minimum Ignition Energy (MIE) for powders?

Here we go. The first blog; let’s begin the blogging and sharing together.

Yes, there are two types of MIE, where one type is carried out without inductance and the other is carried out with inductance.

Minimum Ignition Energy is the minimum energy that is required for ignition of fuel. In other words, the minimum energy an ignition source must provide to the fire triangle for the fuel to burn in presence of an oxidant.
The test to establish MIE is carried out in an apparatus called MIKE3 (refer image below). It is performed using ASTM E2019, “Standard Test Method for Minimum Ignition Energy of a Dust Cloud in Air” or EN13821 “Potentially explosive atmospheres — Explosion prevention and protection — Determination of minimum ignition energy of dust/air mixtures”

MIE (Without inductance) corresponds to the energy required by electrostatic discharge to ignite a dispersed cloud. The circuit of MIKE3 for this test is purely capacitative and the spark energy can be related straight to 1/2*C*V^2 based on the capacitance selected.

MIE (With inductance) simulates the longer duration discharges from electronic circuitry that can occur from machines or control equipment (essentially a spark from short in a wire or electronic equipment) or mechanical sparks, by adding an inductance in the existing circuit.

Now one thing to remember is that MIE (With Inductance) is more conservative as compared to MIE (Without inductance). 

Next question that comes is which one to choose?

And we are Live!!!!

Do you feel trouble understanding Process Safety Concepts? Do you feel that there is no place where someone in Process Safety business is not giving you any information for free? Have you ever felt sitting in a process safety seminar that why the author is not explaining the basic, before going into the detailed concept? Well if that's the case, this is the perfect portal for us to discuss. No one is judging you here for your lack of knowledge or for asking what you considered as a "DUMB" question or a basic concept.

I am a Chemical Engineer by qualification and Process Safety & Risk Consultant by profession catering to various sectors primarily Pharmaceuticals, FMCG, Metal, Chemicals, Plastic & Polymer, Wood & Paper and Oil & Gas. I do perform training, seminars, and webinars with the help of my present employer on different process safety aspects such as Electrostatic Hazards and controls, Dust Explosion protection and prevention, Hazardous Area Classification, Quantitative Risk Assessment, SIL & LOPA, HAZOP, Process Safety Testing for Powders, etc.

I have started this blog to share some of the insights of Process Safety and also to provide solutions to various general queries that we receive on day to day basis. Will also like to share my personal experiences while working on site and some views related to incidents happening around the globe.

Would love, if all the avid readers can share their thoughts and their queries related to process safety here or on my email; so I can continue to upkeep the content on this blog.