Witness to a catastrophic near miss!

On 29.11.1984, I was working  in an ammonia plant when a cylcone hit the place. Management had taken advance action and instructed us to shut off the back end of ammonia plant (the back end of the ammonia plant involves high pressures). We had shut down the back end and were waiting for the cyclone to hit us. The wind speeds were very high and all of us were taking shelter in the control room. A complaint then came in from the  another plant that was located within the same complex, that they were experiencing severe ammonia odour.  Thinking that the pilot burners of the ammonia derrick supported flare that was provided for emergency venting of the ammonia storage tank was put off by the high winds, I requested operators to go out and check them. Three operators had to go, holding each other tightly,as the wind speed was so high and could blow a man off his feet. After a short while they came back and reported that the flare was missing. I went out to check with another team and we found to our horror that the flare structure had collapsed on the main ammonia vapor line coming from the tank. The derrick structure was weak and could not bear the brunt of the wind speeds, but the main flare gas pipe was in good condition and when the derrick toppled, the main gas pipe prevented it from falling all of a sudden. Instead it fell slowly and came to rest on the ammonia vapor line! The 8" main ammonia vapour line from the tank was dented, but did not leak.
When you conduct your asset integrity program, pay attention to structures. Nowadays, in many plants, painting schedules are taking a back seat, with the net result that corrosion creeps in. Corrosion is a silent killer. It will hit you one day if you don't maintain your assets.
Interestingly, recently I read an article where a complete flare structure repair was done with minimum downtime in a plant.Read the article in this link.

Escaping from steam

Many of you will be working with steam. During startups the possibility of water hammer in a steam pipeline has the potential to rupture the line or flange joints. Your SOPs must warn operators about the dangers of water hammer. An article mentions that the best way to escape from a closed space in which a steam leak has been triggered due to water hammer is to escape in the direction in which the steam is leaking through an exit. Read this article in this link

Heat transfer fluids

Paratherm have brought out a good booklet on heat transfer fluids - do's. dont's and best practices. Some of the points brought out are:
"If any hydrocarbon liquid (oil, grease, heat transfer fluid, hydraulic fluid) is allowed to enter porous insulation, it will begin to oxidize, raising the insulation’s internal temperature. If this temperature exceeds the fluid’s autoignition temperature, the fluid is likely to spontaneously combust into a smoldering fire. Thoroughly inspect all insulation for signs of wetness and other damage.Although “hydro” testing is a commonly accepted practice with heat transfer systems,alternatives such as pressure-testing with inert gas or with the heat transfer fluid itself should be considered. Water in a system can cause pump cavitation and corrosion and, if trapped in a “dead leg” and hit by high-temperature oil, can flash to steam and literally blow the pipe or tubing apart. And if the pipe doesn’t burst, the expansion can push a slug of hot oil out the expansion tank’s vent—a serious safety hazard".
Read the complete article in this link.

Blast in melamine plant kills 14

A BBC news report indicates that 14 people were killed in a blast in a melamine plant in China when work was going on an heat exchanger. Read the news report in this link. The cause of the explosion is not known.
The European agency for safety and health and work reports an incident in 2003, in Netherlands, where three maintenance workers were killed when a gas oven in a melamine plant exploded and the three workers who were standing on the cover of the oven fell into it.The gas oven was fired by natural gas and off gases from neighbouring plants. The off gases were contaminated and were filtered before use. The filters had to be cleaned regularly. A short cut taken during maintenance of these filters created a combustible mixture of gas and air in the oven which was ignited by a stray spark. Although this was the immediate cause of the explosion, investigations concluded that the underlying cause was a company culture which had allowed the untested short cut procedure to be used.
The lesson is to follow safe procedures and not to take short cuts even under time pressure. The accident also highlights the importance of the safety culture. Read the report in this link.

Chlorine leak in paper mill

Thanks to Abhay Gujjar for sending information about a chlorine leak from a chlorine dioxide storage tank in a paper mill. Four people are reported taken to hospital.
TAPPI, the leading association for the worldwide pulp, paper, packaging and converting industries has published a booklet on safe handling and storage of Chlorine dioxide. The following points are mentioned:
Chlorine dioxide gas is unstable and readily decomposes to chlorine and oxygen under upset conditions
Chlorine dioxide decomposition is a propagating reaction similar to a combustion front or flame. Providing a sweep of fresh air across the vapor space of a storage tank has shown to reduce the probability and violence of decomposition.
Read the complete guidelines in this link. 
Read about the incident in this link.

Bio Fuels and Process Safety - Ethanol Tanks

The bio fuel industry is growing at a rapid pace. However, from a process safety point of view, it is hazardous as it deals with flammable chemicals like ethanol.  An article mentions the following:
"Steel tanks containing fuel-grade ethanol develop leaks due to stress corrosion cracking, says Oliver Moghissi, president of the National Association of Corrosion Engineers. Corrosion can be an issue near vents and any external appurtenances exposed to air, allowing ethanol to pick up moisture. Storing hydrous ethanol can produce even more corrosion due to higher water content.
There are a number of corrosion mitigation strategies, he adds, drawing on technical input from Narasi Sridhar, vice president of DNV USA, a classification society, and a fellow member of NACE. Galvanic sacrificial coatings, such as zinc or aluminum, will protect steel tanks containing ethanol. The main limitation to this system of corrosion mitigation is that it could have a negative effect on product quality. “Any dissolved metal species in the ethanol can render the ethanol unacceptable to the automotive industry, its main customer,” he tells EPM. “Any galvanic coating therefore must be tested rigorously by the end-user, the automotive community, which can be time consuming and expensive.”
Cathodic protection, however, doesn’t work for the insides of metal structures containing ethanol, the corrosion engineers add. The fuel has low electrical conductivity when compared to water and, as a result, much of the applied voltage is insulated from the metal needing to be protected. “Therefore, impressed or sacrificial cathodic protection systems will not work in ethanol,” Moghissi says. “In ethanol-gasoline mixtures, the situation is even worse since gasoline has a lower electrical conductivity than ethanol.”Read the full article in this link. 

Vacuum - a deadly killer

A news article mentions that a man was sucked into a huge duct conducting gaseous silicic acid that led to his death. The duct was about three feet in diameter. Besides inhaling the gas, he had also suffered injuries on the head while being sucked in. Another employee was also partially sucked into the duct but managed to escape with minor injuries.Read the article in this link.

Dust explosions - status of regulations in USA

An AP news article mentions the lack of regulations in the USA regarding dust explosions.
"Figures compiled by the U.S. Chemical Safety Board illustrate the scope of the problem. A 2006 study reported there were at least 281 dust explosions in the U.S. between 1980 and 2005 that killed 119 workers and injured 718. In 2007, it recommended that the Occupational Health and Safety Administration create workplace rules to control dust and cut down on explosions. The Chemical Safety Board is charged with investigating industrial accidents, but it must rely on regulatory agencies like OSHA to effect change from its findings.
"Despite the seriousness of the combustible dust problem in industry, OSHA lacks a comprehensive standard to require employers in general industry to implement the dust explosion prevention and mitigation measures," the Chemical Safety Board wrote in its 2007 report".
Read the full news article in this link.

Ammonia tank safety valve release

An ammonia tank in a plant in Australia apparently released close to 1 MT of ammonia through its safety valves due to overpressure of the tank. The plant has been ordered to close down.The Government spokesperson  correctly mentions that a safety valve is the last line of defence and this is a serious incident. Many atmospheric ammonia tanks and LPG bullets have their safety valves open to atmosphere. With rampant unauthorized residential settlements still happening around chemical industries and refineries in India, is a disaster waiting to happen?
See the video and report of the incident in this link.
Read a press release of the incident by the company in this link.

More chlorine incidents

Thanks to Mr Harbhajan Singh Seghal for sharing these incidents.

INCIDENT #1
Chlorine leakage was noticed from the valve of a chlorine tonner. They tried to control the leakage but when it became uncontrollable, they dumped the leaky tonner into the alkaline sump to neutralize the remaining chlorine. According to media, about thirty persons complained of eye irritation.
ROOT CAUSE

• 4 Nos filled chlorine tonners were stored since Dec 2008 in the open area. Out of which one toner has leaked
• Valve caps & protection domes were also not provided on these tonners.
• Minor chlorine leakage from the valve of chlorine tonner remained unattended which resulted into a major leak
• Chlorine is a dry gas .On leakage it attracts moisture from the atmosphere and increase the corrosion rate at a very high rate
• Storage in the open makes the accessories weak and further adds up to corrosion

LESSONS LEARNT

• Tonners should be stored under proper shed to protect them from direct sun light & heat.
• Valve caps & protection domes must be provided on the valves of tonners, if they are not being used.
• Regularly chlorine tonners area to be inspected for any chlorine leakage with the help of ammonia torch.
• Even if minor chlorine leakage is noticed, the same must be attended immediately and should not be left unattended.
• Filled Tonners should not be stored for more than 90 days.
• Sufficient nos of necessary PPE’s & tonner emergency handling kit should be readily available at user end.
• Periodic refresher training should be organized for employees handling chlorine tonner.
• Emergency handling procedure should be available at consumer end.

MOST IMPORTANT
Under no circumstance, leaky chlorine tonners should be dumped in alkaline water sump which may cause major mishap.
Tonner keeps floating on the surface of water and chlorine does not neutralize in the solution but spreads in the atmosphere
Chlorine attracts moisture from water and further adds to corrosion
Filler should be informed on first sight of leakage
Even the leaked tonner though empty should be made safe by washing and drying and destroy as per rules

INCIDENT #2
The Incident of bulging of filled chlorine toner occurred but there was no chlorine leakage.
INCIDENT CONTROL
The bulged tonner was immediately depressurized partly by releasing the chlorine to a 200 litre barrel having 5% dilute Caustic lye solution to reduce the pressure & temperature of the tonner and avoid its bursting. Thereafter the tonner was emptied by using the balance chlorine in their process. The emergency could be handled safely & successfully by the chlorine user.
ROOT CAUSE ANALYSIS

• Quantity of liquid chlorine was higher than the desired quantity and moreover the filled tonner was kept in the sun
• The temperature and pressure of the tonner increased due to this.
• The tonner got bulged due to high thermal expansion of liquid chlorine with temperature.

LESSONS LEARNT

• Filling of chlorine toner should be done as per filling ratio-1.19. Water capacityx1.19
• Weight of tonner should be rechechecked after filling
• Filled tonners must be stored in cool and well ventilated place
• Tonner can bulge at 45 degree centigrade with 5%excess filling.it can bulge at any time at room temperature with 10% excess filling

Electrical Safety - part of process safety

Mr Vijayraghavan shared news about an incident in Germany on 4th November when a worker died in an accident during repair work at a petrochemicals hub. The worker died as a result of an electrical shock suffered during repair work on a crane. Investigation is on to determine the cause
Schneider Electric has brought out a very good free safety video on electrical hazards . They mention that “Arc flash accidents that cause serious and sometimes fatal injuries occur five to 10 times every day in the United States. Schneider Electric has produced this electrical safety video as an awareness tool for anyone who faces a risk from electrical accidents that might occur when work is performed on energized electrical equipment. Safety standards are now in place to address the safety of workers who may be exposed to these hazards, as well as to inform employers of their responsibilities to provide employment and a place of employment which are free from recog­nized hazards that are causing or are likely to cause death or serious physical harm to his employees. This video provides information about arc flash, arc blast, shock, and electrocution hazards”.
See the low resolution video in this link
Download the high resolution video from this link and share it with all your colleagues,technicians and operators. It may prevent a fatality.

Domino effects in a disaster

A good example of domino effects of a blast occurred in July 2011 in Cyprus when munitions in a military dump located near to a power generation station blew up. The blast damaged the power station leading to severe power shortages in Cyprus. An article mentions the following:
'Twelve people have been killed and about 30 injured in a blast at a munitions dump in Cyprus. The island's largest power station has been damaged, resulting in widespread power cuts.
The force of the dawn explosions blew out virtually every window in the neighboring village of Zygi and extensively damaged the islands main power station, which remains offline.
Large-scale damage could be seen to a huge section of the barriers of the main Larnaca-Limassol highway and a huge crater about 500 meters from the power station was shown on state TV."
Read the article in this link
See pictures of the blast damage in this link.

Chlorine leak incident

Thanks to Mr Harbhajan Singh Seghal for sending this incident report:

INCIDENT OF CHLORINE LEAKAGE
Two persons were gassed in one of the chlorine consuming industry near Baroda. When the operator disconnected the tonner on the pretext of the hard valve operation of the tonner.
DETAILS OF INCIDENT 

The consumer withdraws liquid chlorine and consumes gas after evaporation.
As per practice the consumer keeps the tonner in line to withdraw maximum chlorine from the tonner.
On the specific date the operator tried to isolate the tonner at 1.0kg/cm2 pressure when about 40-50 kgs liquid chlorine was there in the tonner and ice formation was there at the bottom of the tonner.
He could not close the valve fully. The spindle of the valve damaged due to excessive force.
The operator decided to cut off the tonner by wearing SCBA.
This action resulted in heavy gas and affected two persons in the surrounding 

ROOT CAUSE OF THE PROBLEM

• Liquid chlorine withdrawal rate is 180 kgs/hr. Maximum liquid chlorine is used up in 4-5 hrs operation at this rate. Some quantity 40-50 kgs remains in the tonner at the bottom. Some consumers try to recover this as gas by keeping the tonner in line for more time This Liquid chlorine evaporates at 5-6 kgs/hr as gas and lowers the temperature of the tonner/pipe lines due to fall in pressure till the exhaust of liquid chlorine. 1.0 kg/cm2 pressure can lead to about -20 degree C and takes 8-10 hrs to become completely empty.
• Normally chlorine in the tonner is dry. But under such conditions (-20 degree) the same chlorine become wet. Water in the chlorine separates out and freezes in the sprindle of the chlorine valve. It makes the valve hard to operate at that time.
• After achievement of normal temperature chlorine evaporates first and water later. This chlorinated water reacts with the spindle and makes the chlorine spindle greenish.
• The evaporators which do not have backflow prevention system (from evaporator to chlorine tonner) results carry over of iron chloride rust to valve spindle and makes the valve hard in operation.

ACTION TAKEN

• The tonner brought to the works.
• It was depressurized and valve dismantled.
• Iron chloride rust and greenish color sludge observed in the threading of the valve.
• Damaged valve replaced with new valve.

SUGGESTED ACTION

• The tonners containing some quantity of liquid chlorine are not to be cut off at 1.0kg/cm2 till Chlorine pressure is released to neutralization system through header or evaporator.
• No Cl2 gas from the upper valve of the tonner
• No ice formation appears on tonner or pipe lines after depressurization.
• Chlorine header and evaporator must have chlorine release facility connected to neutralization system.
• Chlorine evaporator must have liquid chlorine flow control interlocked with temperature and outlet pressure to avoid the back flow of chlorine.
• Evaporator should have emergency release system with rupture disc and safety valve.
• Temperature of evaporator should be maintained between 80-85 degree C to avoid formation of rust as FeCl3 in the evaporator.
• Dry air (-40 degree) dew point is to be utilized for evaporation maintenance.
• Glass wool filter is to be utilized in gas line to avoid carry over of Fecl3 to main products and choking in chlorine system.
• Tonners can be kept in tilted position forming 20-30 degree angle to withdraw maximum liquid chlorine from the tonner.

CONCLUSION

• No chance should be taken with liquid chlorine system. Help of the filler must be taken in such cases. One volume of liquid chlorine expands to 460 times
• Chlorine neutralization system must be effective and checked from time to time.
• Single person should not take this type of emergency job.
• Always there should be two persons with safety equipment.

Taking mock drills seriously

Mock drills, if well planned, do deliver inputs where areas for improvements are needed. It is very important to follow up on the results of mock drills and act on them. An off site mock drill conducted in the US demonstrates the seriousness of the effort. In an article about the drill, it mentions that
"The drill, which began just before 9 a.m. Wednesday with the sounding of emergency sirens throughout the county, serves to ensure all emergency agencies in the county are ready in the event of a chemical emergency at the Blue Grass Army Depot, said Justine Barati, congressional liaison with the Joint Munitions Command who also works with CSEPP.A group of 28 evaluators from across the country watched the drill in Madison County, and will report on the strengths and weaknesses of the various agencies’ response, Barati said.Wednesday’s “accident” happened when two people working in the chemical area at the depot fell into some of the chemical. A third person then suffered a heart attack, Barati said. The spill involved an M55 rocket that contained GB nerve agent."
Read the report on the drill in this link.
View a video on another Homeland Security Drill where 300 zombies participated, in this link.

The importance of sight glasses in process safety