With frequent cold waves, how can refining and petrochemical companies survive the winter safely?

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Winters in the north are characterized by low temperatures, dryness, strong winds, and frequent snowfall. These conditions cause many difficulties in people’s daily lives, especially when it comes to outdoor activities, and they further complicate the safe operation of petrochemical enterprises. Before winter arrives, experienced drivers always replace their vehicles’ lubricants and windshield washer fluid with those suitable for low temperatures. So, as \"drivers\" in petrochemical enterprises, how should we deal with the challenges of winter and ensure the safe operation of these large and complex petrochemical facilities throughout the winter? To ensure that the device can survive the winter safely, it is first necessary to understand and grasp the characteristics of winters in the northern regions: Keyword: Low temperatures. Winter temperatures in the north are usually between -15 and 10°C, often below zero. The effects of low temperatures on humans 1) Physical condition: Low temperatures reduce the body’s activity level, dull the body’s responses to external stimuli, and decrease tolerance to external forces. In winter, injuries such as falls and fractures are more likely to occur, and the risks associated with various outdoor activities increase significantly. 2) Heavy clothing: On the one hand, it hinders movement, thereby objectively increasing the likelihood of injuries ； On the other hand, as the number of clothes and accessories increases, risks such as static electricity also increase. Accident case: At 22:30 on January 31, 2008, salt loading was being carried out in a salt storage warehouse at a chlor-alkali plant. The worker named Zhou started the salt feeding machine; his scarf became entangled around the moving drive rod of the machine, which pulled him into it and resulted in his death due to compression. 3) Weakened sense of responsibility: In the harsh winter, routine tasks such as outdoor inspections and monitoring are often carried out in a reduced or altered manner, which subjectively increases the likelihood of accidents and weakens the last line of defense for safe production. Accident case: At 3:30 on February 1, 2010, Zhao was conducting an outdoor inspection at a vacuum distillation unit. When his colleagues went for an inspection at 6:30, they found Zhao collapsed near the pump used to transfer sulfur-containing wastewater from the unit. He was taken to the hospital where it was confirmed that he had died; the cause of death was hydrogen sulfide poisoning. According to the regulations, continuous inspections are required; the inspection frequency at the location where Zhao was injured was once per hour. However, due to the cold weather, the team failed to carry out these inspections as required, which prevented them from detecting and rescuing Zhao, who was unconscious due to poisoning, ultimately leading to his death. Effects of low temperatures on equipment 1) Equipment in contact with water: This refers mainly to equipment whose working medium involves steam, water-containing materials, and various types of water. In winter, temperatures drop below zero, leading to freezing and blockages in pipelines; in severe cases, the expansion caused by freezing can damage equipment, resulting in leaks and secondary accidents. The risk of such incidents is highest when temperatures rise and the ice melts. Accident case: At 16:20 on December 9, 2011, Tang, a worker responsible for insulation work at a fertilizer factory, was carrying out insulation restoration tasks on a 12-meter-high platform surrounding a distillation tower. Suddenly, the vent valve of a 1.0 MPa steam line located on one side of the platform burst, and high-temperature steam sprayed towards Tang. In panic, he fell from the platform to the lower level, resulting in fractures; the high-temperature steam also caused severe burns and serious damage to his respiratory system. The cause of the accident was ice formation inside the valve, which led to its expansion and rupture; as temperatures rose in the afternoon, the ice melted, resulting in the release of steam. 2) Equipment for high-freezing-point media: When the temperature is below the freezing point of the medium, and in the absence of effective insulation, localized condensation of the medium occurs, resulting in a decrease in its fluidity; this quickly leads to a shutdown of the entire process, followed by condensation throughout the system. Since the materials used in refining and chemical processing enterprises are often flammable and explosive, when large-scale and long-distance blockages occur, it is inevitable to resort to measures such as heating or welding operations. The risks associated with these processes are very high, and dealing with such situations is extremely difficult; even the slightest carelessness can lead to significant losses. Accident case: At 7:50 on January 9, 1999, an accident occurred in the residue oil transmission line of a refinery’s atmospheric and vacuum distillation unit due to insufficient heat supply steam, which caused the residue oil to solidify. The residue oil line had a diameter of DN300 and was 1,700 meters long; it was resolved on January 16 through methods such as segmented heating, manual cutting, and replacement. This incident disrupted the production balance of the entire plant, and large amounts of contaminated oil and solid waste were generated during the resolution process, resulting in significant economic losses. 3) Instrumentation equipment: In modern refining and petrochemical plants, the automated control systems supported by various instruments and DCS serve as the operators’ eyes and right hands. In winter, instrument failures caused by low temperatures can lead to localized loss of control in the plant; if the faulty instruments are involved in critical processes or interlock systems, it can result in serious consequences. Accident case: At 7:44 on February 15, 2014, the pressure tapping pipe of the pressure control valve PIC602 located at the top of the gasoline absorption tower in a certain unit froze, resulting in an invalid pressure reading and a failure of the automatic control system. This ultimately led to overpressure in the distillation tower, triggering the activation of the safety valves; a large amount of flammable material flowed into the flare system, causing production disruptions and material losses. Keywords: Dryness. In the dry winter months, the lack of moisture increases the likelihood of fire and explosion accidents. At the same time, dry air hinders the discharge of static electricity, leading to its accumulation; as a result, the possibility of static sparks arising from either workers or moving materials **increases**. The same operations pose no problem in warm and humid seasons, but once winter arrives, the risk of fire and explosion accidents rises due to potential ignition sources. Accident case: In December 2002, in the slurry processing area of a factory in Danyang, Jiangsu, workers were using a vacuum pump to transfer vinyl acetate into a reactor. When about 30 kg remained in the tank, an explosion occurred suddenly, injuring 4 people, 2 of whom suffered serious injuries. The cause of the accident was the accumulation of static electricity as the vinyl acetate material flowed rapidly through the plastic pipes. When the plastic pipes came into contact with the metal tank, a voltage difference between high and low potentials was created, resulting in a spark that ignited the vinyl acetate vapor in the air. Keyword 3: In snowy and icy winter conditions, the impacts of snow and ice on daily life mainly relate to traffic problems as well as slips and falls. In refining facilities, the presence of platforms and ladders makes slips even more dangerous. In addition, excessive snow accumulation also poses a significant risk of collapse due to the load it places on the roofs of buildings and machine sheds. The melting of ice that forms at high elevations can result in ice fragments falling, posing a threat to both people and equipment. After understanding the main challenges faced by petrochemical enterprises in ensuring safe production during winter, how should we respond? In terms of personnel and management: 1) Strengthen the inspection of the implementation of various tasks, urge operators at all levels to overcome weather-related difficulties in order to complete their work more effectively; standardize the use of protective clothing, and strictly control the use of any clothing or accessories other than work uniforms, with special attention to the use of scarves, insulated gloves, insulated masks, and ear protection ； Train employees to consciously discharge static electricity before entering flammable and explosive areas. 2) Arrange work reasonably; for example, when conducting supervision during winter operations, reduce the duration of individual supervision and rotate supervisors more frequently ； Employees are reminded to pay attention to traffic safety after snowfall and ice formation in winter, to be cautious of the risk of ice falling from heights, and to remove snow and ice from the equipment promptly. 3) Before starting work, whether it is the risk identification by the personnel on duty or the training and JHA analysis provided to contractors prior to their operations, it is essential to take into account the characteristics of safe production in winter, and to fully identify and inform them about the weather conditions and the various risks they pose ； During the execution of various tasks, it is necessary to enhance self-protection awareness based on the risks identified prior to starting the tasks, pay attention to one’s surroundings, carry out all tasks in a proper manner, and remind and supervise each other to ensure that risks in winter are under control. 4) Pay attention to and understand the difficulties of working in extremely cold weather during winter. For example, in the reward programs organized by various companies to identify potential hazards, it is necessary to take into account the difficulty of detecting such hazards in cold weather as well as the severity of the consequences they may cause, and accordingly increase the rewards to boost the enthusiasm of employees for their work. In terms of equipment, ensuring its safety through the winter is the foundation and key to safe production during this period. The main focus is on carrying out a series of measures to prevent freezing and condensation during winter, with an emphasis on starting these actions in advance, implementing them thoroughly, and maintaining them throughout the whole season. Six key elements should be taken into consideration: breaking down the winter-related tasks and assigning responsibilities to specific individuals, so that the entire process of implementing each specific measure for safe winter production is covered by designated personnel. For example, in the case of a heat tracing system, one single team is responsible for the entire process – from testing, troubleshooting, operation in low-temperature conditions, making adjustments based on temperature and production levels after it starts operating, inspection and maintenance during use, to shutting it down after winter. This approach ensures both continuity in the work and quality in its execution. Preparations before winter: Planning should be done as early as possible, leaving enough time for the necessary preparations. When scheduling tasks, it is important to take into account uncertainties; for example, testing a steam tracing line may take a few hours, but if leaks are found during this process, fixing those leaks could take a day, and if it turns out that the tracing tubes need to be replaced, that process could take 2 days. Similar situations often occur, so it is important to plan ahead and have a surplus. Preparations before winter: For the auxiliary production areas such as electrical systems and instrumentation, it is necessary to prepare both the professionals and the equipment ； On the other hand, preparations are made to establish communication with production operators regarding special conditions in winter. In actual production, when instrument problems have a significant impact on operations, time is of the essence, and resolving them is difficult, close cooperation between instrument specialists and production staff is necessary to speed up problem resolution; therefore, it is important to define the responsibilities of all parties involved in the emergency handling of instrument issues. During winter: Adjustment of countermeasures. Throughout the winter, due to changes in weather conditions and production adjustments, it is necessary to continuously tweak various measures. A typical example of such adjustment is the steam tracing trap, which needs to be adjusted promptly in response to changes in temperature ； On the other hand, it is necessary to ensure that various measures meet the relevant requirements and are functioning properly; therefore, checking these measures is essential. For example, the status of instruments can be determined by comparing the readings from DCS instruments with those on-site, and the amount of steam used for heat tracing can be checked based on the actual temperature at the site ； After adjustments and inspections, attention should be paid to the handover of tasks; a detailed handover system should be established. Within the contents of shift handovers at each position, winter-related countermeasures should be listed separately, with emphasis placed on the status checks and adjustments of these various measures. Strive to ensure proper inspection and adjustment, thorough inspection, accurate recording, and proper handover. During winter: To address localized freezing incidents as part of a special response plan, it is necessary to develop such a plan in order to control and resolve the issues promptly and prevent them from spreading. When formulating the response plan and carrying out the actual actions, special consideration must be given to the characteristics of winter. For example, when dealing with the problem of valve freezing, cold water should be used first, followed by hot water, and then steam heating should be employed, in order to prevent excessive temperature rises that could damage the valves and lead to larger accidents and losses. During winter: Coping with extreme weather. Winter extreme weather conditions such as extremely low temperatures, heavy snowfall, and strong winds can have a serious impact on both daily life and economic activities; therefore, specific plans for dealing with these conditions should be formulated before winter arrives. When formulating and implementing plans, attention should be paid to the impacts of extreme weather on aspects other than production. For example, after heavy snowfall, travel is severely disrupted, which may prevent replacement staff from arriving at the factory on time; in such cases, the possibility of current staff working overtime should be considered.