Natural disasters, such as earthquakes, floods, hurricanes and storms, often have devastating human and material consequences. They not only leave thousands of people homeless, they may also lead to industrial accidents, triggering massive power outages and damaging chemical plants, oil and gas refineries and pipelines. Forecasts and preventive measure may, in some cases, mitigate their impact but because nature always has its way, they cannot be eliminated completely. The list of such incidents, linking nature and industry has been growing fast since the industrial revolution of the early 19th century.
Most recent on the list are the Fukushima I nuclear accidents in Japan in March 2011. Considered the largest nuclear disaster since Chernobyl, there were no direct deaths but a few of the plant's workers were severely injured or killed by the disasterous conditions resulting from the earthquake. And in October 2012, Hurricane Sandy caused a ConEdison power plant to explode, causing a blackout in most of midtown Manhattan. No person was killed or injured.
Nature, however, cannot always be blamed for industrial accidents. Negligence, incompetence or poor maintenance is often the primary cause of such disasters, resulting in great material damage, injury or loss of life. While the oil, gas and mining sectors have their share of accidents, many other industries – chemical, pharmaceutical or food plants, mills, agribusiness, to name but a few – have had to deal with explosions and fires over time.
The two examples given below, from the 1920s and 1940s, are again part of a long list of occurrences. In both cases, ammonium nitrate fertilizer was involved:
Silo explosion in Oppau, Germany
On 21 September 1921, a tower silo storing 4 500 tonnes of ammonium nitrate fertilizer and ammonium sulfate exploded at a BASF plant in Oppau, a suburb of Ludwigshafen in Germany. Experts later estimated that the explosion was the equivalent of about 1-2 kilotonnes TNT. The blast was of such magnitude that it ripped roofs off and destroyed windows up to 30 km away. About 80% of all buildings in Oppau were destroyed, killing between 500 and 600 people, injuring 2 000 and leaving 6 500 homeless.
Texas City disaster aboard fertilizer-laden ship
On 16 April 1947, an explosion occurred aboard a docked ship, the Grandcamp, in Texas City. The explosion, and subsequent fires and explosions, is referred to as the worst industrial disaster in America. At least 578 people died and 3 500 were injured as the blast shattered windows from as far away as 40 km. Large steel pieces were thrown more than a mile from the dock. The origin of the explosion was fire in the cargo onboard the ship. The detonation of 3 200 tons of ammonium nitrate fertilizer aboard the ship led to further explosions and fires. The fertilizer shipment was to aid the struggling farmers of Europe recovering from World War II.
During the first decade of the 20th century came the realization that coal dust could lead to mine explosions. A series of accidents in the US and in Europe led the authorities to investigate and take the first measures to improve the security of their mine workers. But dust – and the risk of explosion – is present in many other sectors. Flour, sawdust and sugar can be as explosive as coal dust. Vapours, mists and gases are other factors that may trigger explosions when in presence of spark ignition.
Throughout the second half of the 20th century, authorities and industries honed their knowledge and expertise, developing more stringent measures to increase the safety of workers and installations in hazardous environments.
The growing use of electrical equipment by mines and factories made it even more critical to devise appropriate measures, and to standardize all equipment destined for the explosive (Ex) sector. The IEC, sharing the concerns expressed by authorities and industry, set up Technical Committee (TC) 31: Equipment for explosive atmospheres, to “address the need to develop techniques for ensuring electrical equipment would not provide an explosion risk when used in hazardous areas involving gases, vapours, dusts and mists.” For the past 70 years – the TC was set up in 1948 – it has prepared International Standards – the IEC 60079 series – that provide the Ex industry with the strictest requirements covering the whole life cycle of Ex equipment, from design and manufacture to installations, maintenance and repair. They also deal with the competence of personnel working in Ex areas.
The first meeting of IECEx, the IEC System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres, took place in London, UK, in July 1996. With the establishment of a Conformity Assessment System dedicated to explosive atmospheres, the IEC reinforced its presence and growing influence in the sector. From then on, industry, regulators and governments had the tools to ensure that equipment used in hazardous areas did indeed meet the strict requirements enunciated in IEC 60079.
In its more than 20 years of existence, IECEx has extended its offer, leading to the creation of two schemes to complement the original IECEx Certified Equipment Scheme. First the IECEx Certified Service Facilities Scheme, then the IECEx Scheme for Certification of Personnel Competence. And in 2016, following the publication of ISO 80079-36 and ISO 80079-37, it began the testing and certification of non-electrical equipment as well.
IECEx has been endorsed by the United Nations (UN) through the UN Economic Commission for Europe (UNECE) as THE certification system for the assessment of conformity in Ex areas.
Standards, testing and certification, technological advances and increased security measures have definitely helped in the prevention of and decrease in industrial accidents. The more manufacturers and buyers of Ex equipment rely on them, and the more regulators and legislators use them as a basis in their legislation, the better, although their complete elimination may still be a utopia for some years to come.
More information on IECEx: www.iecex.com