Truck and Track Winter 21/22 www.truckandtrack.com 68 DANGEROUS GOODS Our dangerous goods columnist, Ali Karim FRSC CChem, provides an insight into one of the most troubling incidents [the much-feared BLEVE] that can occur in the Dangerous Goods Supply Chain; but most crucially how to avoid the horror of a Boiling Liquid Expanding Vapor Explosion. As well as the associated risk of a Fuel-Air Explosion [FAE] aka a Vapor Cloud Explosion [VCE] occurring mere milliseconds after the BLEVE has breached the pressure vessel and the conditions of a thermal runaway reaction have been initiated. It was a horrific BLEVE and subsequent FAE/VCE incident in Spain in 1978 that initiated the tightening of the regulations on the carriage of dangerous goods by road throughout Europe – namely the Los Alfaques Disaster. The Los Alfaques disaster occurred at a campsite in Spain on the 11th of July in 1978, where a road tanker carrying 23T of Liquefied Propylene caught fire and exploded adjacent to the Los Alfaques Campsite. The fireball caused extensive damage and mass casualties including 217 deaths and over 200 injuries. The aftermath of this disaster resulted in the UK’s Dangerous Substances (Conveyance by Road in Road Tankers and Tank Containers) Regulations, trivially termed the Road Tanker Regulations [RTR] taking priority over the Classification, Labelling and Packaging of Dangerous Substances Regulations [CPR] and the Dangerous Substances (Conveyance by Road in Packages) Regulations [PGR]. These [among other regulations on the carriage of dangerous goods], would eventually become consolidated throughout Europe as ADR [Accord Dangereuse Routiers]. Despite Brexit, UK domestic regulations run in-concert with mainland Europe and Ireland under the ADR framework. But first some context A little while back, my friend the Belfast-based novelist and leading lawyer Stephen Mearns [who writes as Steve Cavanagh] contacted me, regarding his 6th Eddie Flynn thriller. He required a plot device related to Industrial Chemistry. I came up with a scenario related to a “BLEVE”. Steve used it in THE DEVIL’S ADVOCATE, which became a bestseller in The Sunday Times/A C Nielsen UK book-charts on release earlier this year; incidentally it came out in a mass market paperback edition on the 6th January 2022. I would recommend Steve’s thriller as it takes extraordinary literary skill in producing a courtroom drama that is as compelling and thrilling as a car chase, yet remaining deeply thought-provoking. From my consultancy, training and teaching - I offer assistance vis-a-vis Chemistry and Physics on the industrial scale as well as the school and college classroom for KS-4 O-level and KS-5 A-level Physics and Chemistry - Gas Laws, Reaction Mathematics/Dynamics of the activation for Exothermic vs. Endothermic reactions [AQA & OCR Specifications]. Due to my industrial experience of handling liquids and gases [in pressurised containment, tanks, cylinders and in transit] and an academic understanding of reaction mathematics and dynamics, especially of the Exothermic variety; I thought it might be useful to explain what a BLEVE [and the associated FAE/VCE] incident really is, and how one can avoid the risks that bring about this sequence of deadly events. I first encountered a BLEVE, on a small scale at the Fire Training [now called Fire Services] College in Gloucestershire in the 1980s. I was sent for training when I worked on a petroleum pipeline and storage facility outside of London, as part of the emergency team. The BLEVE was simulated using liquefied propane in a pressurised gas cylinder, heated vigorously until the liquid propane boiled resulting in a BLEVE which the trainers put out using abatement foam. The training helped me in my career working in production, storage and transportation of Dangerous Goods, especially in the Middle East, on gas platforms for liquified petroleum gas [LPG] and liquified natural gas [LNG]. I would recommend anyone working with these products [or any dangerous goods that require containment in closed vessels/tanks] attend one of the many courses run at Moreton in Marsh’s Fire Services College [contact details are at the end of this article]. TheMathematics, Physics and Chemistry of a BLEVE A boiling liquid expanding vapor explosion is caused by the rupture of a vessel which could be a holding tank, road tanker, rail car or even a pressurised gas/liquid cylinder that contains a liquid under pressure that has reached [or exceeded] its atmospheric boiling point. The contents of the pressurized vessel can only remain liquid as long as the vessel is intact. If the vessel’s integrity is compromised, the loss of pressure and subsequent rapid reduction of boiling point of the super-hot liquid can [by pressure equalisation with atmosphere] cause the liquid to rapidly convert to gas and expand with exponential and violent rapidity. If the gas is combustible such as a Hydrocarbon [eg BLEVE and the Dangerous Goods Supply Chain by Ali Karim Ali Karim TRUCK & TRAILER SOLUTIONS WELCOME TO ALLPORTS GROUP allportsgroup.co.uk
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