Chemical Accident: Chevron Richmond Refinery Fire

Chemical Accident
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Chemical Accident
Introduction
A huge fire erupted at Chevron Richmond Refinery on August 6, 2012, resulting in a cloud of toxic smoke spreading throughout the town and prompting 15,000 inhabitants to seek medical attention. The Chevron Richmond Refinery is situated in Richmond, California, on a 1,200-hectare property on San Francisco Bay. It is the largest employer in the city (the refinery has 1,200 staff) and processes up to 250,000 barrels per day, with the primary products being diesel fuels, motor gasoline, lubricants, and jet fuel. The chemical accident was caused by old infrastructure and poor disaster management policies. For instance, the explosion resulted from a failure in one of the pipes after years of thinning from channeling crude oil containing high levels of sulfur: sulfur is the primary corrosive element in crude oil pipes. Furthermore, management ignored previous requests for safer equipment, and upon learning of the leak several hours before the fire, they took actions that increased the risk. This essay will reflect on the Chevron Richmond Refinery fire, including the incident's circumstances, the contributing factors to the explosion, and relevant lessons gained from the chemical accident.
Background
On August 6, 2012, a chemical accident at Chevron Richmond Refinery in the #4 Crude Unit owing to a ruptured pipe. The disastrous pipe failure occurred at the "4-sidecut" stream, one of the many process streams in the plant's C-1100 crude Unit Atmospheric column. The C-1100 crude Unit Atmospheric column separates crude oil components into various streams through distillation. These streams undergo further distilling in other refinery units. The 52-inch long section of the 4-sidecut stream raptured while light gas oil (a crude oil component) flowed at 640o F and at a rough rate of 10,800 barrels per day or 315 gallons per minute. This line operated at a pressure of roughly 55 pounds per square inch gauge (Wilson, 2013). The rapture of the piping components resulted in the release of boiling and flammable light gas oil, which engulfed a group of nineteen Chevron employees who had gathered around the leak location to fix the pipe. The partially vaporized light gas oil created a large, opaque plume of smoke and ignited approximately two minutes after the leak. Although eighteen employees managed to escape unhurt before the explosion, one staff (a Chevron refinery firefighter) was caught within the fireball when the light gas oil ignited.
The thick vapor cloud impeded a hasty escape, but the firefighter wore protective clothing and escaped safely through the raging flames. Only six Chevron employees were hurt during the chemical accident and emergency response efforts. However, the leak, ignition, and succeeding combustion of the hydrocarbon process fluid created a large cloud of black smoke, particulates, and vapor, quickly spreading throughout the surrounding city. The atmospheric pollution necessitated the cities of Richmond, North Richmond, and San Pablo to issue a shelter-in-place advisory (SIP) and a Community Warning System (CWS) Level 3 alert. A Community Warning System (CWS) Level 3 alert is usually issued after a significant offsite impact that fulfills any of the three conditions: the offsite impact is likely to result in eye, nose, respiratory, and skin irritation to residents within the area; the fire, smoke, heat, or explosion from the offsite impact lasts longer than 15 minutes, and mutual aid is necessary to mitigate the effects of the event; or/and the offsite impact results in the release of hazardous material. On the other hand, the shelter-in-place directive required residents of the city and surrounding regions to go inside their homes or the nearest structure, turn off air conditioning, close windows and doors, and switch off the heating.
The three cities lifted the SIP and CWS advisories at 11:12 p.m. when the firefighters managed to extinguish the fire. Approximately twenty residents were admitted as inpatients at local hospitals for chest pains and breathing problems. In the weeks after the chemical accident, nearly 15,000 people living in the surrounding regions sought medical attention at local community health centers for related ailments, including shortness of breath, headaches, and core throat (Contra Costa Health Services, 2012). Investigations into the chemical incident concluded that the rapture in the 4-sidecut pipe, including the 52-inch pipe component, was caused by wall-thinning from corrosion. Metallurgic analysis of the raptured pipe revealed that the average wall thickness at the rapture location was less than 10 percent of its original wall thickness. Although the pipe had an original wall thickness of 0.322 inches when it was first installed in 1976, corrosion from ferrying crude oil high in sulfuric compounds had thinned the component's average wall thickness to just 0.0212 inches (Chevron, 2013).
Contributing Factors
The Chevron Richmond Refinery, fire and explosion incident was caused by several contributing factors ranging from poor organizational culture to inadequate safety protocols. Technical findings of the chemical accident showed that the rapture of the 4-sidecut piping was directly caused by sulfidation corrosion. Sulfidic corrosion is caused by the reaction between the iron in the piping and sulfur compounds at high temperatures ranging from 450o F to 1,000o F. The 52-inch pipe component not only ferried hydrocarbon process fluid high in sulfur and sulfur compounds but also at high temperatures: for instance, the average temperature of light gas fuel coursing through the pipe is 640o F. Sulfidation corrosion is quite common in the crude oil sector and the damage mechanism is usually accounted for in all process variables involving steel piping and equipment. Nearly all crude oil feels contain naturally occurring sulfur and sulfur admixtures like hydrogen sulfide. However, the rate of sulfidation corrosion is influenced by certain factors like flow conditions, total sulfur content and sulfur species in the oil, and system temperatures.
Suppose the damage mechanism is not properly monitored or managed. In that case, the steel piping and equipment ferrying crude oil can thin to the point of pipe failure as in the Chevron Richmond Refinery incident. The 4-sidecut piping used to transport light gas oil was made of carbon steel, which has a higher rate of sulfidation corrosion when compared to other piping materials like chromium steel. Moreover, carbon steel is inherently susceptible to sulfidation corrosion when equated to higher chromium-containing steels because of its low silicon content, one of the constituents used in producing steel pipes. The low silicon content in carbon steel piping tends to result in significant variations in sulfidation corrosion rates. For instance, steel pipes with less than 10% silicon weight content can thin up to sixteen times faster compared to steel pipes with higher weight proportions of silicon (Chevron, 2013). Although sulfidation corrosion in carbon steel piping is common knowledge in the crude oil sector, the American Society for Testing and Materials (ASTM) did not enforce stringent regulations relating to minimum levels of silicon in pipe manufacturing until the mid-1980s.
The lack of regulatory oversight in carbon steel pipe production resulted in refineries using pipes with different levels of silicon. It was only until the mid-1980s that pipe manufacturers began to account for sulfidation corrosion rates and comply with industry specifications for silicon content in the steel pipes used in refinery processes. Most of the crude refinery plants in America, including the Chevron Richmond Refinery, were constructed before 1985. Consequently, most of the carbon steel pipe installations in their refinery operations have a lower silicon content than what is recommended by ASTM. For instance, the 2012 chemical accident at Chevron Richmond Refinery was not the first incident. The refinery's original carbon steel piping has a history of failing due to the varying percentages of silicon. The highly variable sulfidation corrosion rates in the refinery's piping and equipment heighten the risk of fire and explosions, as in 2012. For instance, the technical findings after analysis of the 4-sidecut piping revealed that the sample at the leak location had a silicon concentration of just 1%, which exposed it to considerable thinning and subsequent rapture (Chevron, 2013).
Besides inadequate piping infrastructure, the fi...