Index.php?title=Course:SPPH381B/TermProject/Tylenol -Alex Kitt/Petroleum Refining/Fire and Explosions

Fires and Explosions

Due to the use and production of many types of flammable chemicals in petroleum refineries, there is a high risk of fires and explosions. Flammable gases that often cause fires include oxygen, methanol, hydrogen sulfide, methane, and more. Some gases, such as hydrogen sulfide, do not require an ignition source, but may simply combust if the temperature is above the auto ignition temperature (260 degrees Celsius for hydrogen sulfide). Furthermore, vapour build-up in storage tanks increases the risk of explosions .

There are several different classifications of fires depending on the causes, including ‘jet fires,’ vapor cloud explosion, fireball fire, and flash fire. Additionally, there is also a risk of pool fires (combustion of liquids) .

One particularly dangerous part of oil refineries is during transitions, which involves the movement of volatile liquids and nearly 30,000 separate procedures. When the refinery unit is re-started, there is often a risk for excess pressure of liquids to build up. This was the case for the 2005 BP explosion in Texas City, where 15 workers were killed and more than 100 injured . While this accident, and other similar, have had high death tolls in singular events, smaller fires also cause yearly deaths. For example, two separate fires caused three deaths in 2013, one caused by an explosion of a cracking unit, two killed by a flash fire when working on a heat exchanger . Overall, there are an estimated 228 refinery and natural gas plant fires annually .

While the causes of fires and explosions at petroleum refineries vary, there are several guidelines and controls intended to prevent them:

Elimination and Substitution

Given the diverse causes of crude oil refinery fires and explosions, elimination and substitution of causes is very difficult, also because the processes that cause the hazards are required for crude oil processing.

Engineering Controls

Engineering controls utilized include both prevention and monitoring devices. Measuring gas and liquid pressure, smoke, and heat are all recommended . Monitoring of vapour accumulation in storage tanks is also recommended.

Workplace layout is also an important technique in mitigating fire risks, such as separation of combustible liquids and gases from ignition sources and high temperatures . Preventing propagation of fires is also important to limit the area that will be affected in case of fire. This includes adequate drainage systems for oily sewage and accidental spills of flammable liquids, as well as physical barriers such as fire and blast partition walls . Furthermore, planning facilities to include sufficient exit routes and fire fighting access is important in preventing fires from spreading .

Controlling ignition sources is also important for reducing chances of a fire or explosion. This includes using explosion-proof fixtures and double-insulated electrical tools and cables .

There are many different systems that can be used to prevent ignition and spreading of fires. These can include fire water systems, foam systems, and dry chemical extinguishing systems . Water is vital in fire and explosion control, as it both cools equipment and extinguishes fire. However, water cannot be used on all fires, such as pool fires .

Administrative Controls

Administrative controls in the petroleum refinery industry focus on monitoring and maintaining equipment at suggested industry standards, using appropriate warning systems, as well as promoting workplace safety culture.

One cause of fires and explosions at refinery plants includes not following industry recommended guidelines, as was the case in the BP fire in 2005. Had the refinery agreed to upgrade to using flare systems to detect gas leaks as OSHA recommended, the explosion may have been preventable. Furthermore, some casualties occurred because they were staying in temporary trailers that were 'too close' to the refining units . For both of these situations, proper administrative controls would have required that guidelines be enforced, likely limiting the number of casualties.

Promoting proper workplace safety is another key aspect in preventing fires at refinery industries. This involves educating workers on recognizing and limiting potential ignition sources, for example by designating specific smoking areas away from combustible materials . Furthermore, educating workers on warning systems and emergency plans is key to reducing harm caused by fires .

A permit system is also used to reduce fire and explosion risks in refineries. This requires an authorized person to inspect the workplace and issue a permit for work, and covers categories such as “hot work” and “confined space entry hot work,” which are at higher risk for fires .

PPE

There is little PPE that can protect workers from sudden fires and explosions. IHSA recommends wearing clothes made from flame-resistant such as cotton, Nomex, and Proban, as opposed to other options such as nylon or blends .