Chemicals compatibility restrictions and chemical storage safety are tabulated in a Dangerous Goods Segregation Wheel, based on SANS 10231.
Explosives, Class 1 dangerous goods, sodium cyanide Class 6.1, sodium nitrate and potassium nitrate, both of Class 5.1, have compatibility restrictions.
Explosives cannot be stored or transported with any other chemicals and Class 5.1, and 6.1 chemicals should not be stored near each other, nor transported on the same vehicle.
When packages that contain dangerous goods are packed into a freight container, the consignor shall provide a container-packing certificate, specifying the container identifying number and that the packing has been carried out in accordance with certain conditions.
Among these key requirements are that clean, dry and fit containers do not contain goods that are incompatible; that packages have been externally inspected for damage or leakage and that only sound packages have been loaded; and that the freight container and all the packages therein have been properly labelled and placarded.
Chemical storage safety table
CAIA has produced a Dangerous Goods Segregation Wheel that indicates the load and/or storage compatibility of mixed cargoes at a glance, using the class warning diamonds in an easy to use wheel.
It assists in the segregation and storage of chemicals according to their hazard class. This prevents an undesirable chemical reaction from occurring should two or more chemicals accidently mix. It includes useful footnotes.
The Dangerous Goods Segregation Wheel is based on SANS 10231: Transport of Dangerous Goods (R50 +VAT for non-members).
Chinese Tianjin chemical storage disaster
In the wake of the disaster at the northern Chinese port of Tianjin, the Chemical and Allied Industries Association (CAIA) said chemical storage must be managed to minimise the hazards associated with leaks, spills and accidental mixing of incompatible chemicals.
According to news reports, the explosions in China took place at a warehouse, which contained hazardous and flammable chemicals, including calcium carbide, sodium cyanide, potassium nitrate, ammonium nitrate and sodium nitrate.
Calcium carbide reacts with water to create highly explosive acetylene, which may have triggered off the blasts.
Indications are that the firefighters were on site before the explosions. The volatility of the chemicals means the fire was especially unpredictable and dangerous to approach.
State crackdown on chemicals operations
Linkis.com reported that China has ordered a nationwide check on dangerous chemicals and explosives following explosions in Tianjin that left 56 dead and 721 injured.
China’s cabinet also ordered officials to “crack down unwaveringly on illegal activities to ensure safety”.
The operators of the Tianjin site have been accused of “clearly violating” safety rules.
The State Council had ordered “governments at all levels to reinforce the safety management on dangerous chemicals and explosives”.
They should “firmly implement special regulatory measures for highly toxic chemicals such as cyanide, as well as inflammable and explosive materials”.
The reference to cyanide followed reports in the People’s Daily that 700 tonnes of sodium cyanide were at the Tianjin site. Ammonium nitrate may also have been present.
Officials have only confirmed that calcium carbide, potassium nitrate and sodium nitrate were at the warehouse.
Many residents have taken to wearing gas marks despite being told the air is safe.
Chinese officials have admitted discrepancies between accounts from the company and from customs, and that damage to company offices had made it hard to identify the chemicals.
More than 200 chemical and biological experts from the military are on site but officials insist that the air and water quality levels in Tianjin are safe.
Beijing News reported that sodium cyanide was detected in the sewage and leakage.
The Tianjin facility, operated by Ruihai Logistics, had “clearly violated” safety rules that say dangerous materials must be stored at least 1km away from public buildings and main roads.
State media said the manager of the Ruihai Logistics site had been detained.
Fire officials have defended the actions of the team who responded to the initial report of a fire on Wednesday night, amid suggestions that using water on some of the chemicals could have led to the blasts.
Calcium carbide reacts with water to create the highly explosive acetylene.
They would not have sprayed water on calcium carbide, although it was a large warehouse and the team could not be sure where that substance was.
An acetylene blast could then have detonated ammonium nitrate to create a much larger blast.
There were two explosions. The first was equivalent to about three tons of TNT, the second – some 30 seconds later – was equivalent to 21 tons.
• Sources; www.caia.co.za or +27 (0)11 482 1671. Linkis.com.
Domestic fuel storage query
Gerhardt Nel asked; Is there any South African law or regulation regarding DOMESTIC storage of petrol and diesel? Are their limits applicable? I have tried to research this on the internet but got no answer.
Edmond Furter responds; Gerhardt, I have referred your query to a lawyer. The Major Hazard Installation regulations may be relevant, since the volume threshold for some materials is quite low.
Domestic sites are not exempted. The MHI Regs are in revision, perhaps CAIA has a ready answer for you in that context.
The 20 litre metal cans, and specified plastic cans, are popular. I would recommend that such cans be kept in vehicles, secured upright, and that carports and car garages are cleared of other flammables, waste bins, and spark sources, such as grinders and batteries.
There should be municipal guidelines on domestic power generators, their placement, their fuel storage, and their connection. There is a SANS standard on co-use of grid electricity and generators that may be references in some laws and by-laws. Perhaps the Fire Protection Association FPA has a ready answer for you in that context.
As usual, general awareness and housekeeping will prevent more disasters than any legislation.
Lawyer Shavanya Subramoney replies; I have checked the national legislation, but I cannot find anything that deals with a domestic limit.
The Major Hazard Installations only deals with workplaces. If you work from home, then this would be applicable.
The Hazardous Chemical Substances Regulations also deals with storage at workplaces.
In addition to Edmond’s suggestions, you may check your local municipals by-laws, as well as with your local fire station.
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