Hydrocarbon Fire
Large-scale blaze and the challenges in containing it is what makes hydrocarbon fire one of the most dangerous classes of fire. These infernos are intense, fast spreading and are able to reach temperatures of 1200°C and above in a span of a few minutes. A fire in such magnitude always has the potential to trigger explosions when it is not contained early. The immense heat would melt steel rapidly causing structural collapse, threatening lives and damaging properties. At these higher temperatures, the tensile and yield strength of steel is immensely compromised. When steel is exposed to 500°C, only 45% remains of its strength and stiffness, whereas at more than 1100°C exposure, steel begins to liquefy, its hardness, yield and durability is reduced considerably as the temperature rises.
Hydrocarbon fire is subdivided into two categories: jet fire and pool fire. The former is when a pressurized gas line leaks, allowing the combustible liquid to scatter at the same time filling the surrounding air with vapor cloud. Given this scenario, it would take just one tiny electrostatic spark to generate a fire that is so destructive in scale and magnitude. This is not just limited to offshore, oil & gas facilities but in all industrial sectors where hydrocarbons: petrol, diesel, methane, propane, butane, acetylene, heptane, methanol, acetone and other various solvents and their likes are utilized. Pool fire on the other hand is when spilled flammable liquids are ignited creating a vertical fire directly above the horizontal liquid pool. This has the strong possibility for accelerated spread and escalation due to the abundant presence of fuel to sustain the burning coupled with the prevailing ventilation and wind velocity in the area. The bigger the pool of combustible liquid, the more explosive the resulting fire would be as the volatile liquids are vaporized and burned in a continuous cycle. A fire is termed as under-ventilated when it is enclosed or inside confined spaces. This would result in a smoke-rich environment due to incomplete combustion. The restricted oxygen translates to pyrolysis, which concludes in the formation of dense smoke and the generation of toxic gases due to partial incineration.
Mitigating hydrocarbon fire threat starts first with crafting risk assessment for the environment where the volatile liquids are stored and used. Rigorous safety measures need to be enforced starting with the creation of a fire emergency contingency plan. Life-threatening scenarios and escalation of fire progression can be halted when the proper active and passive fire protection systems are in place. Maintenance and regular testing of fire suppression system including the smoke and gas detectors are prerequisites to prevent equipment failure when the critical situation arises. Another significant aspect is the training of the personnel on the proper storage, handling and transport of hydrocarbons. Promoting proactive emergency response training and regular fire safety drills to ensure full compliance to safety protocols should be mandated.
Design strategies that are essential in lowering hydrocarbon fire risks include the installation of blast-resistant coverings to reinforced key sectors and equipment, segregating high risk areas to prevent rapid fire spread, the use of emergency isolation valves to closed off fuel supply in case of leaks and the utilization of passive fire protection (PFP) solutions like intumescent coatings in combination with non-combustible mineral wool for sealing gaps in between curtain walls and the application of high temperature fire insulation wrap for structural steel.
