Learn Lessons from Incidents

The Directorate General, Factory Advice Services and Labour Insitutes (DGFASLI) has published a number of incidents on their website. I have separated the process incidents and given them below. Learn lessons from them.

Incident 1:"In a chemical factory yellow phosphorous was converted into red phosphorous in a rotary furnace. When the yellow phosphorous was cooked in the rotary furnace for its conversion to red phosphorous at 244^oc, water which was surrounding the yellow phosphorous, became steam. When steam was vented, it carried away certain amount of phosphorous and this caused the vent line choke. This ultimately increased the temperature and pressure of the vessel. Temperature shot up to 300^oC and pressure was not being monitored. Suddenly the furnace exploded and the stored up hot gases caused flash fire injury on the worker and subsequently he died. Causes :

• The outlet for the generated steam and system pressure was chocked by the phosphorous and there was a pressure and there was a pressure temperature built up in the vessel
• Pressure was not monitored by the pressure gauge installed in the furnace
• No safety valve with the proper scrubber arrangement was not installed in the furnace".

Incident 2: "On 18-07-2004 at 06.02 P,M, the Captive Power Plant feeding electrical supply to Cell House - II got tripped due to a flashover (earth fault). This resulted in the tripping of load in Cell House - II and a few motor drives in other sections. But the Cell House-I continued to function, producing Chlorine as it was being operated on EB Power. There was a Chlorine Scrubber system which was a packed column and whose function was to absorb the chlorine gas by means of the circulating lime slurry, in the event of any operational upsets in the process and chlorine free air was vented to the atmosphere. There is a chlorine gas compressor in the chlorine liquefaction section, the compressor sucks the chlorine which is evolved in the cell during electrolysis and compresses it for chlorine liquefaction. Since both the Chlorine scrubber blower and the Chlorine Compressor also got tripped along with the Cell House - II, the Chlorine gas which evolved from the Cells of Cell House – II came out freely and drifted along with the wind toward the adjoining villages. No casualty. Causes:

• Emergency power supply was not provided to the Chlorine absorption system to meet out any problem of power interruption during emergency of chlorine leak
• Cell House – I and Cell house - II were not provided with interlock arrangements in such a manner that if one cell house trips due to operational problem, the other cell house also gets tripped instantaneously".

Incident 3: "In a factory, where 10 MT weak sulphuric acid was stored, suddenly the suction line valve tank nozzle assembly got broken and through this opening sulphuric acid drained out from the tank and this resulted in vacuum formation in the tank. This FRP tank hit against the supporting channel legs due to the formation of vacuum. Causes:

• The FRP tank was not maintained with a adequate strength and stability
• The FRP tank was not tested and certified by the Competent person every year"

Incident 4:"In a fertilizer factory, as the granulator discharge chute got chocked the plant was stopped and the workers cleaned the choked discharge chute by means of poking. After cleaning, the plant was, started without feeding the raw materials namely phosphoric acid, sulphuric acid and ammonia; the granulator was put on dry run. Meanwhile, the heavy lump which caused the block in exhaust ducting fell down and consequently the unreacted ammonia, came out from the discharge end in the form of heavy puffing and injured 5 contract workers. They were given medical treatment in Government hospital and were discharged later. Cause: Un-reacted ammonia in the granulator came out from the discharge end in the form of heavy puffing and injured the workers"

Incident 5:"In a pharmaceuticals manufacturing industry, after the bulk drug is produced the solvents are recovered by distillation in solvent recovery plant. In this instance, a flash distillation still, T-302 was used for the recovery of solvent, Dimethly Sulfoxide (DMSO) in the Solvent Recovery Plant. A batch quantity of 5 KI. of 75% concentration DMSO was charged into the still T-302 in which 700 mm. of Hg vacuum using a piston vacuum pump and a temperature of 136~ were maintained. When this batch was going on and 2.5 KI. of DMSO was inside T-302, there was a hissing sound and immediately after the hissing sound was heard by the worker the still T-302 exploded with a fire ball, killing a chemist and another chemical engineer. The control room which was located very close to the Solvent Recovery Plant was heavily damaged in the explosion. There were so many joints, flanges and gaskets in the pipe line along the DMSO vapour route on the vacuum pump side. Hence failure of such parts might have led to leakage of air in the circuit and could have caused air DMSO explosive mixture. Causes:

• DMSO is a flammable liquid. It has a flash point of 80°C and flammable range from 2.6% (volume) LFL to 63% (volume) UFL. Hence when the still, T-302 is at 136°C, vacuum is absolutely necessary to rule out air entry and to prevent fire. Before the explosion, a hissing sound was heard by a witness; this indicates that vacuum still T-302 could have failed due to development of hole (s) through which air entered and formed an explosion.
• As air ingressed the still T-302, static charges could have been generated due to mixing with the DMSO. The static charges generated could have ignited the explosive mixture, leading to explosion and fire ball"

Incident 6: "In a fine chemicals manufacturing industry, chemicals like 2 – amino Di-bromo-benzly alcohol, manganese dioxide and toluene were loaded into the 4 KL stainless steel reactor (SSR5) and heated upto 65-70 degree centigrade and agitated in the above process. The resultant product layer was settled and filtered in SS nutsche filter by transferring through a HDPE hose. The remaining layer containing toluene was unloaded in a 200 litre HDPE barrel which was not provided with proper earthing or bonding to dissipate the static electric charges and hence fire broke out and spread to the nearby nutsche filter and SSR 6 reactor. Cause: HDPE barrel which was not provided with proper earthing or bonding to dissipate the static electric charges and hence fire broke out".

Incident 7: "A chemical factory had erected three MS cylindrical storage vessels with a capacity of 24 KL - 2 nos. and 30 KL - 1 no. At the time of incident, a tanker lorry with 24 KL petroleum product was brought to the premises for the purpose of unloading into the installed storage tanks. The workers tried to unload the petroleum product into the left extreme vessel of the 3 vessels (30 KL capacity) by using the rubber hose, one end of the rubber hose was connected to the outlet valve of the lorry and the other end of the rubber hose was connected to the 30 KL horizontal tank valve. While transferring the material, there was some leakage at the point of outlet valve connected to the rubber hose. In order to control the leakage, the workers decided to move the lorry to correct position. The driver started the tanker lorry and immediately there was a sudden fire noticed at the outlet valve leakage area. The workers tried to put out the fire but they could not do so. Fire spread out to the other area and consequently the storage vessel got suddenly burst out and thrown out from its foundation. Because of this explosion, the petroleum material became a fire ball, causing minor burn injury to about 23 onlookers and nearby factory workers.Causes :

• The petroleum product which is very highly flammable in nature was unloaded from the road tanker to the M.S. tanks without providing proper bonding to the road tanker and the storage tank; also earthing to avoid the risk of static electricity was not done.
• While the petroleum product was leaking through the rubber hose, the driver started the tanker lorry. The small sparks released from the exhaust pipe, ignited the petroleum product vapour, resulting in fire and tank explosion".

The above information has been obtained from this link.

Ammonia leak from storage tank vent

A leak of about 20 pounds of ammonia has been reported from a DuPont ammonia storage tank in Belle, USA. The leak was detected by a sensor which sounded an alarm. As per the article, "No one was injured in the incident.DuPont spokesman David Hastings said the incident occurred at about 2:30 a.m. and the all-clear was sounded shortly after 3:10 a.m".
It is good that the detector worked as intended. Many times, gas detectors are unreliable for detecting leaks. Some companies are now using computer modeling to determine the number of detectors and their required placement. How sure are you that your detectors will work as intended?
Read the article about the leak in this link.

Sulphuric acid tanker leak kills a woman

Thanks to Abhay Gujar for sending this info. A sulphuric acid road tanker that broke down in Jajmau area was being shifted by a crane when it reportedly got damaged and sulphuric acid got into sewers. The fumes entered a bathroom where a woman was killed. The safety of road transportation of chemicals is a big issue in India, with a number of acid tankers plying the roads. Some of them are not in road worthy condition. The onus is on both the supplier and receiver to ensure that safety rules for transport of hazardous cargo are followed to avoid such tragic deaths.

Read the article in this link.

Use of HF in refineries

An incident has been reported in a refinery in the US where a HF release reportedly occurred. The article mentions the following:
"A hydrofluoric acid leak from an oil refinery in Ohio last week sent a worker to the hospital and required the use of a “water cannon” to disperse the poisonous gas, underscoring the potentially perilous nature of a chemical used at 50 refineries across the country.
HF is used as a catalyst to make high-octane gasoline, despite the existence of a safer alternative and warnings about the chemical’s extreme toxicity and its ability to travel long distances in a cloud. The Center for Public Integrity and ABC News reported last week that at least 16 million Americans live in the potential path of an HF release".
Read the full article in this link
Read the MSDS of HF in this link.

Know the chemicals you deal with

An incident took place when phosphoric acid was inadvertently unloaded into a storage tank containing 12.5% Sodium Hypochlorite solution. The resulting chemical reaction of the two caused a chlorine gas release which affected the field operator. In another incident, a chemical that could be thermally decomposed was inadvertently stored near a steam pipe. The resulting heat transfer from the steam pipe caused a thermal decomposition later caused a fire in the warehouse in which the chemical was stored. Many of us do not treat chemicals with the respect they deserve. MSDS need to be understood by the people who handle chemicals. It is not just a matter of pasting the MSDS in the place where the chemicals are stored. it is a matter of understanding them.

Accident to truck carrying hydrogen cylinders

Thanks to Abhay Gujar for sending this information - A truck carrying 180 hydrogen cylinders overturned due to a burst tyre in an highway (NH-8) resulting in the drivers cabin catching fire. Luckily, the cylinders did not explode. Now, the motor vehicle rules clearly specify the rules for dangerous cargo, including fitness of the vehicle carrying it. If you are transporting cylinders through trucks, ensure that the vehicle is in roadworthy condition. Imagine what would have happened if all the 180 cylinders overheated and burst!
The local news article link is attached.

Temporary solutions - permanent problems!

Management of change is the most difficult element to implement as it requires a lot of commitment to make it work. Very often, temporary changes can have a devastating effect. A safety officer mentioned to me about a temporary electrical cable that was laid across an internal road. To protect the cable, it was inserted through a metal pipe. The cable was energised and work was going on. However, the a portion of the pipe was damaged and a piece of the metal was actually cutting into the cable everytime a vehicle moved over the pipe. Luckily an alert fitter noticed this and an incident was avoided. Do not take the temporary route or shortcuts in process safety.

Read about a boiler explosion that occurred due to a temporary change in this link.

A Bhopal in the USA?

An article highlights the possibility of a bhopal type disaster happening in the US. The article mentions the following:
"Bhopal should have been a wake up call, but it is unclear whether chemical plants around the world are any safer a quarter century after the December 1984 disaster—during which some 40 tons of toxic methyl isocyanate gas leaked from a pesticide plant owned by Union Carbide (now part of Dow Chemical), killing 2,259 people immediately and causing lifelong health problems and premature death for tens of thousands more.
In the U.S., the Occupational Safety and Health Administration (OSHA) oversees chemical and other facilities that deal with hazardous materials, making sure various “process safety” routines are followed so as to “prevent or minimize the catastrophic injury or death that could result from an accidental or purposeful release of toxic, reactive, flammable or explosive chemicals.” Also, in the wake of the 9/11 attacks, the U.S. Department of Homeland Security instituted its own “Chemical Facility Anti-Terrorism Standards” (CFATS) that chemical and other hazardous materials facilities must follow or be shut down.
While this system has worked pretty well in the U.S. so far, some worry that a Bhopal-scale tragedy, whether due to an accident or terrorist attack, could still occur on American soil. For one, water treatment and port facilities are exempt from CFATS altogether, so some of the nation’s largest chemical facilities are not subject to as rigorous standards as they could be. A 2009 bill that passed the House of Representatives but failed to make it through the Senate addressed this and other issues. Supporters are optimistic that the bill in one form or another could resurface in future legislative sessions".
Read the article in this link

And the Flare goes "BOOM" at night!

When I was working in the Middle East, we had a 80 m tall flare that sat in the middle of the plant. After a few years we started hearing "BOOM" noises from the flare when the plant was running normally. The noise was heard more often at night. The "BOOM" used to be muffled and there was no external evidence of an explosion in the flare and the plant continued to operate without interruption. We did a lot of investigation and finally caught the culprit that was allowing air into the system. Treat your flare systems with respect. They are mute spectators when everything is normal but can save the day during an emergency!
For a good presentation on flare systems see this link

Read these process incidents

The department of occupational safety and health, Malaysia has these process incidents put up on their website. Follow the links to learn useful lessons:
1. Combustible dust explosion in motorcycle rim manufacturing facility
2. Fire and explosion in LPG facility
3. Fire and explosion in LPG storage
4. Fire and explosion in biotechnology factory (static electricity)
5. Fire in bulk petroleum storage tanks
6. Fire and storage in LPG storage facility
7. Combustible dust explosion

The Buncefield Investigation - be prepared to see similar findings elsewhere

The HSE, UK has published the investigation report of the explosion and fire that occurred in the Buncefield oil depot in the UK, in December 2005. The main findings are quoted below:
"Fundamental safety management failings were the root cause of Britain's most costly industrial disaster, a new publication reveals.

• Systems for managing the filling of industrial tanks of petrol were both deficient and not fully implemented
• An increase in the volume of fuel passing through the site put unsustainable pressure on those responsible for managing its receipt and storage, a task they lacked information about and struggled to monitor. The pressure was made worse by a lack of necessary engineering support and other expertise.
• A culture developed where keeping operations going was more important than safe processes, which did not get the attention, resources or priority status they required.
• Inadequate arrangements for containment of fuel and fire-water to protect the environment.

 The 36-page report highlights a number of process safety management principles, the importance of which were underlined by the failings at Buncefield:

• There should be a clear understanding of major accident risks and the safety critical equipment and systems designed to control them.
• There should be systems and a culture in place to detect signals of failure in safety critical equipment and to respond to them quickly and effectively.
• Time and resources for process safety should be made available.
• Once all the above are in place, there should be effective auditing systems in place which test the quality of management systems and ensure that these systems are actually being used on the ground." 

In only few organisation do I see the above 4 points religiously followed. In all of them, there is a common link - the person at the top is a person with a hardcore chemical engineering background and plant experience. In all other cases, the top management are persons without such experience and incidents continue to happen. In such cases, the organization must ensure that a person with proper experience should be in a position to act as a link between top management and the plant. While on the same subject, today LOPA has become a fashionable word for many managements but they do not realize that once a LOPA study is carried out and recommendations implemented, they should be maintained for the complete life cycle of the plant. For this it requires resources and manpower and  these are often found wanting. Keep your fingers crossed!!
Read the HSE report in this link.

Hazards of low oxygen inside confined spaces

I got this information from a safety officer of a large company that happened in his company 20 years ago. A vessel had to have its rubber lining repaired. The adhesive used for holding the lining to the solvent was expensive and the contract labourers who were handling it were told to handle it carefully and not to spill it. However, when one contract labourer was entering the vessel by a ladder, he inadvertently lost grip on the open can of adhesive and it fell down to the floor of the vessel. In order to cover up his mistake, he and another co-worker entered the vessel quickly and tried to apply the adhesive to the walls of the vessel. Due to the sudden increase in adhesive concentration in the confined space, the oxygen level decreased and both died of asphyxiation.
Today there are accidents that still continue to happen on the above lines. Learn from history. Do not allow more people to die.

Another natural gas explosion

The aging natural gas pipeline network in the USA has experienced another pipeline explosion. This explosion has killed 4 persons. Authorities are trying to determine whether an determine whether a 83-year-old cast-iron gas main or its feeder lines was the source of the explosion. A news article mention the following:

"The fiery blast late Wednesday night was the latest deadly natural-gas disaster in recent months to raise questions about the safety of the nation's aging, 2.5-million-mile network of gas and liquid pipelines.The explosion, which flattened a pair of rowhouses and set fire to a block of homes, occurred in an area where the underground gas main lacked shut-off valves. It took utility workers five hours of toil in the freezing cold to punch through ice, asphalt and concrete and seal the 12-inch main with foam, finally cutting off the flow of gas that fed the raging flames.An Associated Press investigation published Saturday found that many pipelines around the country are not equipped with remotely operated or automatic shut-off valves that can quickly stop the flow of gas in an accident, even though federal safety officials have recommended such devices to industry and regulators for decades".

Read the article in this link.

Preventing fires in thermal fluid systems

Many chemical industries use variety of thermal fluids for their reactor heating/cooling systems. There is often a lack on the part of the user on the hazards of the thermal fluids and the importance of proper specification and maintenance. Most of the thermal fluid systems operate above their flash points. I read some good technical papers by Paratherm Corporation. Excerpts from the articles are given below:
"Fluid leaking from valves, gasketing,welds or instrument ports finds its way into porous insulation and wicks through. Remaining as hot as the system itself, the fluid comes into intimate contact with the air in the insulation's millions of pockets. As it enters each pocket, the fluid oxidizes and decomposes—in the process using up the existing air and creating heat. Confined within the insulation, the heat has little chance of escaping. The continued oxidation causes temperatures to rise. In some cases temperatures may exceed the autoignition point of the fluid. Should the insulation be opened up when the system is hot, fresh air will immediately enter. Coming into contact with the hot, partially oxidized fluid, fresh air can cause spontaneous ignition resulting in a smoldering fire, or a flash".
The paper also recommends precautions to be taken in component selection, installation and maintenance.
Read the paper in this link. Read another article on Prevent fires in thermal fluids

Disclaimer: I am not advocating any product and am sharing this information in the interest of process safety

CSB safety videos

I am quite surprised at the lack of awareness of personnel in the chemical industry about the good work the Chemical Safety Board of the US is doing. The CSB is an independent federal agency investigating chemical accidents to protect workers, the public and the environment.

They have many free safety videos on their website which should be shown to every person in the chemical industry. The videos are available in this link.

Hydrogen gas detection in refineries

I chanced upon a good article written by Gassonic on hydrogen gas detection in refineries. The article mentions the following:
"There are several hazards associated with hydrogen, ranging from respiratory ailment, component failure, ignition, and burning. Although a combination of hazards occurs in most instances, the primary hazard with hydrogen is the production of a flammable mixture, which can lead to a fire or explosion. Because its minimum ignition energy in air at atmospheric pressure is about 0.2 mJ, hydrogen is easily ignited. In oil refineries, the first step in the escalation of fire and detonation is loss of containment of the gas. Hydrogen leaks are typically caused by defective seals or gaskets, valve misalignment, or failures of flanges or other equipment. Once released, hydrogen diffuses rapidly. If the leak takes place outdoors, the dispersion of the cloud is affected by wind speed and direction and can be influenced by atmospheric turbulence and nearby structures. With the gas dispersed in a plume, a detonation can occur if the hydrogen and air mixture is within its explosion range and an appropriate ignition source is available. Such flammable mixture can form at a considerable distance from the leak source.
In order to address the hazards posed by hydrogen, manufacturers of fire and gas detection systems work within the construct of layers of protection to reduce the incidence of hazard propagation. Under such a model, each layer acts as a safeguard, preventing the hazard from becoming more severe.The detection layers themselves encompass different detection techniques that either improve scenario coverage or increase the likelihood that a specific type of hazard is detected. Such fire and gas detection layers can consist of catalytic sensors, ultrasonic gas leak monitors, and fire detectors. Ultrasonic gas leak detectors can respond to high pressure releases of hydrogen, such as those that may occur in hydrocracking reactors or hydrogen separators. In turn, continuous hydrogen monitors like catalytic detectors can contribute to detecting small leaks, for example, due to a flange slowly deformed by use or failure of a vessel maintained at close to atmospheric pressure. To further protect a plant against fires, hydrogen-specific flame detectors can supervise entire process areas. Such wide coverage is necessary: Because of hydrogen cloud movement, a fire may be ignited at a considerable distance from the leak source".
Read the article in this link (pdf file -be patient)

Disclaimer: The reader is recommended to to do a survey before purchasing detectors.

Natural gas pipeline explosion and ethanol rail tankers derailing incidents

Thanks to Abhay Gujar for sending this info. A major fire has been reported in a natural gas pipeline explosion in a plant in Texas. One Worker was killed. Read about it in this link.
Another incident involved the derailment and catching fire of ethanol rail tankers near Ohio. The article mentions that "Twenty-six cars of a 62-car Norfolk Southern train jumped the tracks at about 2:20 a.m. in Cass Township, and the contents of those that ruptured in the impact caught fire. The denatured ethanol in other tank cars that were not breached immediately was heated by the flames until it boiled and the tanks could no longer withstand the pressure, causing explosions that sent fireballs bursting spectacularly into the sky".
Read the article in this link.

Students campaign - "Crackdown on cracking crackers"

I was happy to receive a mail from Arijit Chanda, a student of Pondicherry Engineering College regarding assistance for a campaign they were planning to create awareness about the safety in firecracker bursting and avoidance of child labour in their manufacture. Though I could not contribute to their cause, I was happy to hear from him that their campaign went off well and was reported in the Hindu. The article in the Hindu about their campaign is given in this link. Kudos to Arijit and the team!

Exothermic explosion causes serious injury

A news article mentions that a 58 year old man was seriously injured when he was was in the process of mixing sodium cyanide pellets with hydrogen peroxide at a Chemical plant, when the volatile solution exploded, soaking him in the hot toxic mixture.
"An investigation by the HSE revealed that approximately five times too much hydrogen peroxide was added to the sodium cyanide pellets which resulted in an exothermic explosion".
Train your workers on the hazards of inadvertent reactions. Read the article in this link.
Read another article about the same incident in this link.

Another tragic confined space entry fatality - train your workers about the hazards

The Indian Express has reporetd a confined space entry fatality in a chemical factory near Pune. Apparently, a worker entered the confined space without any protection,after the can from which he was adding adhesive fell into the vessel. He got inside the vessel and was then overcome by the toxic fumes. Another worker who entered to save him was seriously injured. The rescue crew had to cut an opening in the vessel to rescue the trapped persons. It is sad that the vessel was not designed as per standards with manholes of standard dimensions. How many more lives will be lost in confined space accidents? It is important to train your workers on the hazards of confined spaces and requirements for a confined space entry permit. Also, train your people to overcome the urge to enter a confined space to rescue a fellow worker, without proper protection. It is a natural human tendency to enter a vessel quickly to save a fellow colleague, but it is a very dangerous practice if proper respiratory protection is not worn. Read more in this link.

In another incident that occurred some time back, a young engineer in a fertiliser plant in India was killed when he slipped into a vessel under nitrogen atmosphere. He was trying to check the work done inside the vessel from outside when he reportedly slipped inside.