Interpretation of the Ten Regulations on Fire and Explosion Prevention in Oil and Gas Tank Farms

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Interpretation of the “Ten Provisions on Fire and Explosion Prevention in Oil and Gas Tank Farms” On August 4, the **State Administration for Work Safety issued the “Ten Provisions on Fire and Explosion Prevention in Oil and Gas Tank Farms” (hereinafter referred to as the “Ten Provisions”), which consist of 275 words and specify the prohibitions regarding daily management, safety facilities, special operations, and personnel qualifications in oil and gas tank farms. The “Ten Provisions” are aimed at addressing the prominent issues identified through major and typical accidents that have occurred in oil and gas tank farms in recent years. Based on on-site management and a problem-oriented approach, they are formulated in accordance with the Work Safety Law of the People’s Republic of China, the Regulations on the Safety Management of Hazardous Chemicals, as well as relevant departmental rules, regulatory documents, **and industry standards. Every one of the Ten Provisions is a lesson learned through bloodshed; each one represents a lifeline, a red line with strict constraints, and a boundary that must not be crossed. The safety of oil and gas storage areas is of great importance, attracts significant attention, and has wide-ranging impacts; any loss of control can lead to serious consequences. All enterprises must ensure that there are strict rules, thorough enforcement, comprehensive coverage, effective implementation, and tangible results. To thoroughly comprehend and accurately understand the contents and requirements of the “Ten Provisions”, a clause-by-clause interpretation is provided below: 1. It is strictly prohibited to operate oil and gas storage tanks under conditions of excessive temperature, pressure, or liquid level, as well as to arbitrarily change the stored medium. This article mainly stipulates the requirements for the use and management of oil and gas storage tanks. The storage medium, storage temperature, pressure, and liquid level in oil and gas storage tanks must comply with the designed process conditions and process control parameters. Deviations from these parameters can lead to safety risks such as leaks, fires, and explosions. During the design phase, storage tanks are designed for a specific storage medium, with the design considerations limited to the physical and chemical properties of that medium as well as the requirements of its storage and transportation processes. If the storage medium is to be changed, it is necessary to determine whether the existing design parameters of the tank meet the requirements for storing that new medium, in order to ensure the safe operation of the tank. Arbitrarily changing the storage medium or the purpose of the storage tank can pose safety risks and lead to accidents. Typical accident case: On March 31, 1984, an explosion occurred in a oil tank at a petrochemical plant in Baoding City, Hebei Province, resulting in 16 deaths and 6 serious injuries. The main cause of the accident was the illegal introduction of residue oil (which was originally intended for use as boiler fuel) into the tank; the high oil temperature caused a large amount of gas to mix with the air inside the tank, forming explosive gases that ignited upon contact with sparks. II. It is strictly prohibited for operators to leave the site while manually draining water, disconnecting tanks, or loading/unloading vehicles in the oil and gas tank area. This article mainly specifies the management requirements for manual water isolation, tank isolation, and loading/unloading operations in the tank farm. Manual water removal refers to the process of intermittently opening the water release valve by hand to discharge the water accumulated at the bottom of the oil and gas storage tank; tank transfer involves switching the material in and out from one storage tank to another; loading and unloading refers to putting material into a storage tank or transferring material from a transport vehicle into a storage tank. Operations such as water cutting, canning, loading and unloading must be carried out in strict accordance with safety standards, procedures, and regulations, under the on-site supervision and oversight of designated supervisors throughout the process. If proper supervision is not provided, it is very easy to cause oil and gas leaks, leading to accidents. Typical accident case: On October 22, 1988, an explosion and fire occurred in the spherical tank area at the refinery of Shanghai Gaqiao Petrochemical Company in Xiaoliangshan. The incident resulted in 26 deaths and 15 people being injured. The main cause of the accident was that the operators failed to follow the operating procedures when opening valves to drain water from the spherical tanks; there was no one on site to supervise the process, which led to liquefied gas being discharged together with water. Due to delayed response, the liquefied gas ignited upon contact with an open flame, causing an explosion. On July 16, 2015, an explosion occurred in a liquefied gas spherical tank at Shandong Shida Technology Petrochemical Co., Ltd., also as a result of water cutting operations being carried out in the tank area; the workers left the site, leading to a leakage of liquefied gas and delayed response to the situation. III. It is strictly prohibited to shut down the safety valves and isolation valves of operational oil and gas storage tanks, as well as to install blind flanges on the pressure relief and discharge systems. This clause mainly specifies the safety operation requirements for safety valves and pressure relief systems. A safety valve shut-off valve refers to a shut-off valve installed in front of and behind a safety valve to facilitate its testing or replacement. A pressure relief and discharge system is a system that can quickly release the pressure in a storage tank, typically referring to a flare system or a dedicated discharge system. If the safety valve or cut-off valve is closed, or if a blind flange is installed on the pressure relief system, the tank will be unable to release pressure in case of overpressure or an emergency, leading to serious accidents such as explosions and fires due to excessive pressure. Typical accident case: On July 16, 2015, a fire and explosion occurred in a liquefied gas spherical tank at Shandong Shida Technology Petrochemical Co., Ltd., resulting in minor injuries to 2 firefighters, the destruction of 7 fire trucks, and varying degrees of damage to some of the spherical tanks as well as surrounding facilities and buildings. The direct cause of the accident was that, during the tank transfer operation, once all the water in Tank No. 6 was removed, liquefied petroleum gas leaked out through the connection pipes and spread; it then caught fire upon encountering an ignition source, resulting in a fire in the liquefied hydrocarbon tank area ； The spherical tank exploded due to the shutdown of the safety valve and the installation of a blind flange on the pressure relief system, which exacerbated the consequences of the accident. IV. It is strictly prohibited to shut down the temperature, pressure, level, as well as combustible and toxic gas alarm and interlock systems in oil and gas tank farms. This provision specifies the management requirements for alarm and interlock systems related to key parameters such as temperature, pressure, liquid level, as well as flammable and toxic gases in oil and gas tank farms. Oil and gas storage tanks must be equipped with level gauges, thermometers, pressure gauges, combustible (toxic) gas detectors, as well as high-level alarms and automatic interlock mechanisms to cut off feed at excessively high levels, in accordance with relevant standards and specifications. The alarm signals should be transmitted to the control room or operating room where operators are stationed. Additionally, audible and visual alarms must be installed so that any abnormalities can be detected and addressed promptly. Therefore, it is essential to ensure that the alarm and interlock systems remain in good condition and operational at all times. Typical accident case: On December 11, 2005, a fire and explosion occurred at the Buncefield oil depot in the UK. More than 20 large storage tanks were destroyed in the incident. Forty-three people were injured, and the direct economic loss amounted to £250 million. The main causes of the accident included a malfunction in the automated measurement system of the storage tanks; electronic monitors and related alarm devices for certain tanks and pipeline systems were also not functioning properly. V. It is strictly prohibited to perform welding work or enter confined spaces in oil and gas tank areas without conducting gas testing and obtaining an operation permit. This article mainly stipulates the management requirements for hot work and confined space operations in oil and gas tank farms. Before carrying out hot work, it is necessary to analyze and test the concentration of combustible gases in the area around the point where hot work will be performed in the oil and gas tank area. Before entering confined spaces, it is essential to analyze the levels of combustible and toxic gases as well as oxygen content within the tanks. Hot work and entry into confined spaces have always been operations prone to accidents. Oil and gas tank farms store large quantities of materials; thus, any accident that occurs can have serious consequences. Strict approval and management procedures must be implemented. Potential hazardous and harmful factors at the work site and during the operations should be identified, and corresponding safety measures should be formulated and put into effect. Relevant personnel must sign off on these measures according to their authority. During the operations, supervisors must be present to oversee the process. The specific management procedures should comply with the requirements set forth in the “Safety Regulations for Special Operations in Chemical Production Enterprises” (GB30871). Typical accident case: On June 2, 2010, an explosion and fire broke out at the triphenyl tank area of Sinopec Dalian Petrochemical Complex, resulting in 4 deaths. The direct cause of the accident was that workers from an illegally subcontracted contractor carried out gas cutting operations on the roof of one of the storage tanks in the triphenyl tank area in violation of safety regulations; the flames from the cutting ignited flammable and explosive gases such as toluene, and the backflow of these flames into the tank led to its explosion. On October 27, 2004, an explosion occurred in an acidic water tank at CNPC Daqing Petrochemical, resulting in 7 deaths. The main cause of the accident was the leakage of explosive gas mixtures from cracks in the tank walls, which then ignited due to open flames from gas cutting operations or flying slag. VI. It is strictly prohibited for the floating disk of an internal floating roof storage tank to touch the bottom during operation. This article mainly specifies the requirements for the liquid level in internal floating roof storage tanks. Float pad touchdown occurs when the liquid level in the tank is too low, causing the float pad to rest on the support legs. During normal operation, once the floating disk settles at the bottom, a gas space is formed between the disk and the oil surface. When the flow rate of the material is too high, static electricity tends to accumulate at the outlet of the material pipeline, which can easily lead to fires and explosions. Typical accident case: On August 29, 2011, an explosion and fire occurred in a diesel tank at CNPC Dalian Petrochemical. The main cause of the accident was the low liquid level resulting from oil being supplied to the tank; this created a gas space between the floating disk and the surface of the diesel, allowing air to enter ； At the same time, fluctuations in the operation of the upstream units led to an increase in the content of light components in the diesel that entered the emergency storage tank, resulting in the formation of an explosive mixture beneath the floating disk ； Additionally, the excessively fast oil inflow rate generates a large amount of static electricity, which cannot be dissipated in time, leading to discharge and subsequently causing an explosion and fire. VII. It is strictly prohibited to directly add substances of unknown properties or those that may undergo violent reactions into oil and gas storage tanks or the pipelines connected to them. This provision sets out the safety management requirements for the use of various additives and auxiliaries in oil and gas processing and blending. Before adding them for use, it is necessary to understand the physical and chemical properties of the additives and auxiliaries, conduct risk assessments, and establish corresponding control measures and emergency plans. During the operation process, a specialized additive system should be used, and the operating procedures must be strictly followed. Typical accident case: On July 16, 2010, an explosion and fire occurred in the oil transfer pipeline of the tank farm operated by Dalian CNPC International Storage and Transportation Co., Ltd. The main cause of the accident was the continued injection of crude oil desulfurization agents containing strong oxidants into the pipeline, even after the crude oil tanker had stopped unloading oil; this led to a violent reaction within the pipeline, resulting in an explosion and a fire. VIII. The use of non-explosion-proof lighting, electrical equipment, tools, and electronic devices in oil and gas tank farms is strictly prohibited. This article mainly specifies the requirements for the use of explosion-proof equipment in oil and gas tank farms. The media stored in oil and gas tank farms are generally flammable and explosive. Using non-explosion-proof tools, electrical equipment, communication devices, etc. in such areas poses significant safety risks and can easily lead to accidents. Typical accident case: On June 29, 2010, a deflagration occurred at a crude oil storage tank at PetroChina Liaoyang Petrochemical. The incident resulted in 5 deaths and 5 injuries. The main cause of the accident was that during tank cleaning operations, hydrocarbon combustibles in the tank reached their explosive limits; upon encountering an electric spark generated by a non-explosion-proof ordinary lighting fixture connected to the tank, a deflagration took place. 9. It is strictly prohibited for untrained personnel and contractors without relevant qualifications to perform work in the oil and gas tank farm. Without permission, motor vehicles and external personnel are not allowed to enter the tank farm. This article mainly stipulates the training requirements for operators at the work sites, as well as the management requirements for contractors, external personnel, and motor vehicles. Operators of oil and gas tank farms must be properly trained and competent to perform their duties. It is a prerequisite for ensuring the safety of operations that contractors entering the tank farm possess the appropriate qualifications; unauthorized personnel and motor vehicles entering the tank farm can introduce many uncontrollable safety risks. Typical accident case: On October 21, 1993, an oil tank explosion occurred at the Sinopec Jinling Petrochemical Refinery, resulting in 2 deaths. The main cause of the accident was that the operators violated the operating procedures, which led to gasoline leakage and the formation of an explosive mixture in the air; this mixture ignited when exposed to sparks from the exhaust pipe of a tractor driven by a contractor, causing a fire and explosion. X. It is strictly prohibited to operate equipment and facilities in oil and gas tank farms when they are in poor condition or malfunctioning. This article mainly stipulates the management requirements for equipment and facilities in oil and gas tank farms. The storage tanks, pipeline fittings, safety accessories, lightning and static electricity protection systems, fire emergency equipment, and other facilities in the oil and gas tank farm must be regularly maintained to ensure their proper operation. Typical accident case: On January 7, 2010, an explosion and fire occurred at a C4 spherical tank at PetroChina Lanzhou Petrochemical. The incident resulted in 6 deaths and 6 injuries. The main cause of the accident was the failure and rupture of an elbow fitting in the outlet pipeline of the cracked C4 spherical tank, leading to a leak of the material. The leaked cracked C4 reached its explosive limit; upon encountering an ignition source, it caused a spatial explosion, which in turn led to leaks, fires, and explosions in nearby storage tanks.