Fire accident at an oil field refinery: 2 deaths | Case study

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At 15:25 on December 29, 1999, a fire broke out at a refinery belonging to an oil field when the steam purge line at the outlet of the slurry steam heat exchanger was disconnected, resulting in 2 deaths and 2 minor injuries. Course of the incident: On December 23, the catalytic unit of a refinery discovered that the steam purging line (DN25) at the slurry outlet of the slurry steam exchangers (E211A, B) on the cold exchange framework platform had frozen and broken. On the afternoon of December 28, Xia XX, the deputy director of the catalysis workshop, discussed with Lu XX, the deputy director of the maintenance workshop, to arrange for safety officer Xu XX to get in touch with the factory’s safety department in order to prepare for shutting down the steam purging lines at exits E211A and B. At 8:30 on December 29th, Ding XX, a safety inspector from the factory’s safety department, went to the catalysis workshop together with Xu XX, the workshop’s safety officer, to inspect the site; thereafter a level-1 fire use permit was issued. Around 9 o’clock, personnel from the maintenance workshop arrived at the site to carry out work, but since the engineering vehicle did not have gas welding equipment, cutting work could not be carried out, so it was agreed to resume the work in the afternoon. At 15:00 on December 29, the maintenance workshop assigned Chen XX, Shi XX, Zhang XX, and Niu XX to the catalysis workshop. After Xia XX, the deputy director of the catalysis workshop, Xu XX, the safety officer, and Chen XX, the section leader from the maintenance workshop, inspected the work site once again, both parties agreed to start the cutting operations without notifying Ding XX, the safety inspector from the factory’s safety department, to be present. During the construction process, due to the lack of necessary fixing measures, when one end of the steam purging line for E211B was cut in preparation to cut the purging line at the other end of E211A, the joint where the steam purging line met the slurry outlet line (DN200) suffered a crack that covered two-thirds of its length at the spot where it was welded to the flange. Slurry at around 350°C sprayed out from the crack and caught fire spontaneously, resulting in the immediate death of Shi XX; Zhang XX died despite attempts to save him, while Sun XX and Niu XX sustained minor injuries. Analysis of the accident cause: Based on the on-site investigation, it was determined that this was a fire-related casualty incident caused by the failure to detect obvious safety hazards in a timely manner and by illegal welding operations. The main reasons are as follows: 1) The design did not provide for support or hanger fixation for the steam purge line (DN25), which is 3.46 meters in height and 4.74 meters in length and hangs suspended; the connection point between this line and the slurry outlet line is under significant stress, and the original welds on this line had defects – it was found that two-thirds of the welds at the break site were not fully welded. The refinery failed to recognize this obvious safety hazard; over the years it failed to identify issues such as the lack of supports and hangers on the pipeline, as well as the risk of the pipeline freezing in winter. 2) Fire permit management was not strict; after the operators changed, new fire permits were not issued, and welding work was carried out without the presence of a welding supervisor. At the same time, the construction workers lack a strong safety awareness; they do not fully understand the risks associated with performing welding work in flammable and explosive areas or with fires caused by hot oil slurry. They violate the principle that \"in plants operating under normal conditions, welding work must be strictly controlled, and any components that can be removed should be taken to a safe location where such work can be carried out.\" 3) Safety measures were not implemented; there were no necessary operation plans or fire-related precautions. Temporary supports were not considered during construction, and the sequence of operations for cutting the pipelines was unreasonable. As a result, after one end of the pipeline was cut, a 13-meter-long steam purging pipeline ended up hanging suspended with only one support, which caused cracks in the welds at the pipeline-flange connections. This led to an accident in which hot oil slurry was spilled, resulting in injuries and fatalities. Lessons from the accident: 1) Thoroughly implement all safety production regulations, make serious efforts in their enforcement, and resolutely combat all types of violations. 2) Thoroughly identify potential hazards associated with equipment, pipelines, etc., analyze the possible impacts of low temperatures in winter, and promptly eliminate all such hazards. 3) During equipment maintenance, thorough risk identification must be carried out; the fire permit system must be strictly followed, and a fire watch officer, an appropriate work plan, as well as corresponding safety measures must be implemented.