Another Chlorine leakage incident

Thanks to Mr Harbhajan Singh Seghal for sending this incident:
On 18.8.2010 a message was received from Emergency Control Room regarding chlorine leakage in one of the consumers near Vadodara. Immediately the emergency team was sent to attend the problem.
PROCESS / ACTIVITY : The consumer was filling liquid chlorine from 900 kgs to 100 kgs. Cylinders by keeping on weigh balance. The tonner (900 Kgs.cap.) was pressurized with Nitrogen from upper valve. Lower valve of the tonner was connected with the withdrawal pipe fitted with filling valve to 100 kgs. Chlorine cylinder. There was a provision to release withdrawal pipe gas in 200 ltrs. drum containing caustic 100 kgs.
CAUSE OF INCIDENT: During transferring process from 900 kgs. to 100 kgs. liquid chlorine in 900 kgs. tonner exhausted. Pressure of the tonner suddenly gone up due to nitrogen padding. This resulted in very heavy vibration in the withdrawal pipe. Due to this, connection at the both ends was disturbed and damaged the corroded fittings and filling valve due to physical impact. This resulted in heavy gas release from the tonner and cylinder side.
ACTION TAKEN :

• Both the valves of 900 kgs. tonner and 100 kgs. Cylinder were closed after wearing the SCBA (Self Contained Breathing Apparatus).
• Fire hydrant team sprayed water externally to restrict gas in the outer area.
• Police Deptt. controlled the external public for further exposure.
• 10 persons affected with gas during the process were admitted in the hospital which were discharged after first aid.
• Spilled chlorine hydrate was neutralized with Caustic Soda gradually.
• All the tonners were brought back to the plant as per the advise of Explosive Deptt. and depressurized.

All the tonners condition and valves were checked and found perfectly in working order. TECHNICAL / LEGAL LAPSES :

1. Filling of liquid chlorine from 900 kgs. to 100 kgs. was not authorized from Deptt. of Explosives.
2. 900 kgs. Tonner was pressurized manually with Nitrogen pressure from cylinder (max. pressure 150 kg/cm2).
3. Max. pressure required to transfer liquid chlorine to toner is about 10 – 11 kg/cm2 where as uncontrolled pressure was applied manually. It disturbed the transfer process due to high pressure in tonner.
4. There was no well set chlorine neutralizing system. Neutralization was done in 200 ltr. Drum containing caustic.
5. Brazing of copper tube and chlorine valve used for filling was badly corroded and brazing workman ship was very poor. The fitting was not tested at desired pressure.
6. No safety equipments were maintained by the consumer to control any emergency.

LESSONS LEARNT :

1. Filling of liquid chlorine into the tonners can be done after getting the necessary approval from the Deptt. of Explosives.
2. A well set system has to be provided for filling and neutralizing from safety point of view. It is a very unsafe process to transfer liquid chlorine without proper facilities and competent persons
3. Corroded fittings are not be used. Withdrawal pipes needs to be tested and replaced regularly.
4. Provision of pressure regulator and pressure gauge in the line / header is a must.
5. All the safety equipments and gas mask should be readily available.
6. Provision of vacuum system connected with chlorine neutralization system can help to control chlorine hydrate gas due to liquid chlorine spillage.

Electrical area classification

Many plant operations, electrical maintenance and process engineers often get confused about electrical area classification. Electrical area classification is an important part of process safety. Read a succinct explanation of electrical area classification in this link.

Process safety and security - facility siting

A news article mentions the presence of a warehouse containing ammonium nitrate near refineries and fertilizer plants in Visakhapatnam. Recently, the Govt. of India has recently brought Ammonium Nitrate under the explosives act after its usage by terrorists.
The article mentions the following:
"At the time of setting up of this facility in 2007, there was a furore. After the environment assessment report was presented before the MoEF (ministry of environment and forests), the matter went for public hearing, which saw many local residents protesting storage of this hazardous substance, backed by some political parties as well. "But like in many other cases, public objection was overlooked and the government cleared the project, which is again illegally built on the CRZ (costal regulation zone) area," said Mr Sarma.
"Vishakhapatnam is a busy and an important area," he added, "it is a major Coromandel port, it houses the headquarters of the Eastern Naval Command, is an ecologically sensitive zone and is an industrial and commercial hub. Several incidents—from the 26/11 massacre to the sinking of MV Rak—have shown us how vulnerable our coastlines are. In such a situation, storage of explosive substances like ammonium nitrate is a big risk, especially when there are no checks on it."
Read the article in this link.

The importance of lube oil

Many process incidents have been initiated by a shutdown of a critical equipment due to problems in the lube oil system. A short but good article titled "3 reasons why lube oil fails" written by Jeremy Wright highlights contamination, oil degradation and additive depletion as the 3 reasons why lube oils fail. Read the article in this link.

Hydrogen cylinder fire incident

A fire in a plant in the US where hydrogen cylinders on a trailer caught fire has been reported. See the photos of the fire in this link. Apparently a supply line was being repaired at the time of the incident.

Sodium nitrite explosion kills 2

A blast in an disinfectant manufacturing unit in China has reportedly killed two persons. The unit uses sodium nitrite. A fire is reported to have caused the explosion. The MSDS of sodium nitrite mentions the following:
"Special Remarks on Fire Hazards:
When in contact with organic matter, it will ignite by friction. May ignite combustibles.
Special Remarks on Explosion Hazards:
Explodes when heated over 1000 F (538 C). Sodium Nitrite + thiocyanate explodes on heating. A mixture of sodium nitrite and various cyanides explodes on contact. Mixture of sodium nitrite and phthalic acid or anhydride explode violently on heating.Fusion of urea with sodium nitrite Interaction of nitrites when heated with metal amidosulfates (sulfamates) may become explosively violent owing to liberation of nitrogen and steam mixed with ammonium sulfamate form. Violent explosion occurs if an ammonium salt is is melted with nitrite salt. Shock may explode nitrites. must be carried out exactly as described to avoid risk of explosion".
Read the news article in this link.
See the MSDS of sodium nitrite in this link.

Do awards and certifications help process safety management?

I have been hearing about incidents in India (some fatal) in organisations that are recognized by their peers or have been awarded certificates and awards for their safety performance. Receiving awards and logos is one thing and making a continuous 24X7 commitment to process safety is another. A friend was mentioning about an incident in an organisation in India,which has all the certifications and peer recognitions in place, where a reactor exploded killing few persons. The reaction which was highly hazardous in nature was apparently being carried out manually. During the end of the shift, the operator noticed that the reactor's steam jacket valve was passing, but apparently failed to communicate this to his relief operator. The temperature increase caused a runaway reaction to occur destroying the reactor (details about pressure relieving devices are not known) . My friend visited the unit a few months after the incident and he observed that many of the employees were not even wearing basic PPE!

I have also visited organizations in India where process safety is managed excellently and is ingrained into their way of work. What I noticed in these organizations is that most of them do not go for external recognitions but concentrate on getting their house in order on a daily basis.A good process safety management program's reward is judged by NOT having process incidents and process near misses.

Hazards of Nitrogen trichloride

Thanks to Mr Harbhajan Singh Seghal who has shared his presentation in the World Chlorine programme in Brazil last year, about the hazards of nitrogen trichloride in the chlorine manufacturing industry. Quoting from his presentation, "Nitrogen Tri-Chloride is one of the most hazardous material in Chlor-Alkali industry. Fatalities have occurred and workers have been injured by NCl3 explosions.The explosive power of small quantity of NCl3 can be catastrophic & can cause release of Chlorine & large scale damage to personnel, plant equipment . NCl3 is sensitive to light, impact and ultrasonic radiation. A spontaneous explosive compound, Explosive potential is 30% of TNT".
See his presentation in this link

Chlorine incident

Thanks to Mr Harbhajan Singh Seghal for sending this case study:
CASE STUDY OF CHLORINE LEAKAGE

 INCIDENT :

Chlorine leakage took place from the bottom of 100 Kgs. chlorine cylinder at one of the water chlorination plant situated in a populated area.
ACTION TAKEN :
- The consumer informed the FIRE BRIGADE and the manufacturer.
- Fire brigade reached the site at the earliest and the manufacturer reaches after 1.5 hr. being 100 km away. By the time situation was under control.
- Fire brigade put the leaking cylinder in the underground pit with MANHOLE.
PROBLEM EXPERIENCED IN CONTROLLING CHLORINE LEAKAGE:
- The cylinder started floating on the surface of water in the pit and gas started coming out from the MANHOLE.
- Additional weights were tied with cylinder to keep it dipped.
- Additional water had to be pumped as still some gas was coming out.
- It took about one hour to control the situation in the populated area. No body in the area was affected
OBSERVATIONS:
- The cylinder was 15 years old
- It was tested hydraulically 20 months earlier.
- Pitting & dents were observed at the bottom side near the STAND.
- Pin hole had developed in the pitting area near the welding of the stand.
- There was no safety equipment, neutralizing system with the consumer.
- No proper loading / unloading system of Cl2 cylinder was there.
- No provision of Ammonia torch / ammonia was there to check leakage during connection / disconnection stage. Corrosion was observed in the chlorination system.
POSSIBLE REASONS OF LEAKAGE:
- Some moisture in the cylinder before filling or backflow of moisture after getting the cylinder empty due to inadequate barometric leg or malfunctioning of chlorination system can result pinhole.
- Unloading of the cylinder by dumping on the ground results dent and makes the surface weak and some times develops pin hole.
- Storage of the cylinder at wet and muddy place excel rate corrosion in the cylinder surface.
- Old cylinders were designed as per Ammonia cylinders code which has tolerance of scattered porosity in the plate of the cylinder & welding against NIL porosity in the present standard IS-3196. Minor leakages were observed in such cylinders also at any time. Now, the permission is not given to such cylinders, only latest code is followed.
- Most of the consumers are withdrawing Cl2 at higher rate which results ice formation on the outer surface of the cylinder. Also gas nuisance is observed in the area due to poor connection or bad MOC particulars gaskets. In the presence of moisture & gas nuisance, chlorine cylinders and Cl2 valves are badly affected and results emergency sometime.
- Most of the consumers do not keep Ammonia Torch at site and not checking leakage at the time of connection / disconnection and on regular basis. This overlooking also causes chlorine leakage beyond control.
SUGGESTED ACTIONS :
- Cylinders are to be stored at concrete flooring under a covered shed. These should be loaded / unloaded with the help of hoist / chain block / on the plate-form to avoid any damage.
- Ammonia Torch should be kept nearby. No leakage should be allowed.Two to Three times leakage should be checked in the shift.
- Extra precautions to be taken while filling cylinder in checking moisture, physical examination of cylinder & painting etc. Cylinders with external pitting / dents should be rejected . Consumer should provide barometric leg in their system.
- Consumers need to be educated for safe handling of chlorine from time to time. Consumers should have all safety equipments, chlorine neutralizing system and competent persons.
- In case of leakage cylinder / tonner is not to be put in water. It results higher chlorine release due to poor solubility of chlorine in water and cause serious emergency. It should be handled by vacuum blower & neutralizing system only.
- At the first site leaky part of the cylinder / tonner should be brought on the upper side. This results reduction in Cl2 leakage by 15 times. By increasing the consumption rate of chlorine after above action, lowers the temperature / pressure of the cylinder and results further reduction in leak rate and gives some relief time for emergency action.
CONCLUSION :
- Cl2 leakage can be handled safely by competent persons with the help of safety equipments and chlorine neutralizing system.
- Cl2 handling system need to be audited and persons need training from time to time.
- Standard guide lines are to be followed for safe handling of chlorine.

Three killed by CO leak in steel plant

The Deccan Herald has reported an incident in a steel plant in Bellary, where three people were killed due to CO leak. The article mentions

"Three workers, including an assistant manager, died on the spot after inhaling carbon monoxide at the Jindal (JSW) steel factory at Toranagal in Bellary district early Tuesday morning.

Lack of precautionary measures is the cause of the incident, said District Superintendent of Police Dr Chandragupta, who visited the spot. A case has been registered at the Toranagal police station. The incident occurred when the trio came to the gas container at the blast furnace unit 2 of the energy management division (EMD), climbed down into the ‘U’ seal pot and turned the valve on to check the pipeline. The three men had gone to check the gas container on getting information from the control room that the gas level had slumped". Read the article in this link.

Insulation can burn!

Abhay Gujar has sent news about an insulation fire in a shoe factory in Hanoi, that killed 17 people. According to the news article, "The welder was installing a lightening rod on the factory's tin roof in preparation for a tropical storm that is expected to hit northern Vietnam later Saturday. The insulation fell to the factory floor in a fireball, blocking the 150-square-metre workshop's only entrance before quickly engulfing piles of shoemaking materials, it said".
Some insulating material can burn. Make sure you read the MSDS of your insulating material before attempting any hot work.

Handle waste with care

Waste chemicals can cause major issues if not handled properly. In 2007, an explosion took place in an waste aerosol can shredder unit in the UK An article about the incident mentions the following: "The HSE discovered that the machine had not been designed to safely shred waste containers containing residues of flammable liquids and gases. Furthermore, unsafe operating procedures were in place".
 The general human tendency when dealing with the ETP or waste handling is NOT to treat as seriously as an operating plant. With many waste treatment facilities being outsourced, make sure that you have robust systems in place to avoid incidents.

Read the article in this link.