Approximately 6 people were injured due to the excessive opening of the sampling valve! How to effectively prevent accidents during the sampling process?

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On September 9, a toluene leak occurred at a fine chemical company, injuring 6 people. The preliminary cause of the accident was that, when the operator was taking samples from the hydrogenation reactor, the sampling valve was opened too wide, resulting in a large amount of toluene leaking out. The harmful gases generated by evaporation caused poisoning symptoms in the workers on site; some of them also suffered irritation from these volatile gases, leading to burns to their respiratory tract and eyes. Chemical manufacturing companies often use sampling facilities to collect representative samples from equipment and piping systems for analysis, which is an important method for quality control. However, since samples often involve flammable, toxic, explosive, or high-temperature and high-pressure substances, companies do not pay enough attention to the sampling process; as a result, accidents related to sampling have occurred frequently in recent years. Relevant accident cases: Case 1: On December 21, 2024, during the trial production phase of the DPC-1 unit in a chemical manufacturing company in Zhangzhou, which has an annual production capacity of 180,000 tons of PC (polycarbonate), a leakage occurred as a result of material solidification and blockage in the phenol sampling pipeline. Operators took samples at the drain point of the phenol feed preheater in violation of safety procedures, resulting in 2 deaths and 1 injury. Case 2: On May 31, 2024, at a coal chemical company in Liaoning, at the temporary sampling point for blast furnace gas pipeline located above the south-side wall of the finished product warehouse in the synthesis area, analysts from the product manufacturing department and the chief engineer in charge of equipment management in the synthesis area violated the analytical procedures by taking samples of blast furnace gas without any safety precautions, which led to poisoning and asphyxiation incidents; the chief engineer in charge of equipment management died as a result of this accident. Case 3: On September 6, 2023, a certain energy technology company in Inner Mongolia failed to provide systematic training on the operating procedures for relevant positions; the personnel working on those positions did not know or were not familiar with these procedures, and there was no one on site to oversee safety matters. At the PTMEG finished product loading and unloading station, gas sampling was conducted on the top of the tractor-mounted container tank (to analyze the oxygen content after nitrogen displacement). The sampler went to the site alone to take samples, entering the container tank without authorization, which resulted in the sampler’s death due to nitrogen asphyxiation. Case 4: On June 3, 2022, an poisoning incident occurred in the wastewater collection and regulation tank of a chemical manufacturing company in Ningxia, resulting in 2 deaths and mild poisoning among 5 people who were involved in the rescue efforts. The direct economic loss amounted to approximately 2.874 million yuan. The main cause of the accident was the creation of a confined space after the cover was installed on Tank 1, the wastewater collection and adjustment tank at the sewage treatment plant. During the process of adjusting the pH value of the wastewater, toxic and harmful gases such as hydrogen sulfide were generated and accumulated. When the operators removed the cover from the observation and sampling port of Tank 1 without wearing protective gear, hydrogen sulfide gas leaked out from that port, resulting in the operators being poisoned. Rescue workers carried out rescue efforts blindly without wearing protective gear, resulting in an increase in casualties. The enterprise has not established safety operating procedures for sampling and testing wastewater pH, nor has it effectively supervised workers entering the sewage storage area to use portable detectors for toxic and harmful gases as well as gas masks while carrying out their tasks. Case 5: On February 7, 2020, a fire broke out at a petrochemical company in Guangdong; no injuries were reported, but the direct economic loss amounted to approximately 34,500 yuan. The operator failed to use specialized tools for sampling; instead, he violated regulations by going to the bottom of tank TK108, opening the drain valve of the instrument transmitter, and using a plastic sampling bottle to collect samples from the drain outlet. The plastic sampling bottle generated static electricity discharge, which ignited the combustible gas mixture and caused a fire. Case 6: On September 30, 2019, a liquefied gas storage and transportation company in Jiangsu carried out sampling operations simultaneously during the loading of toluene. Static electricity was generated when a self-made sampler was lifted from the liquid phase inside the toluene tank truck, which ignited the explosive mixture in the upper part of the tank truck, resulting in a fire and explosion. This incident caused 1 death and 1 injury, with direct economic losses of around 3 million yuan. Case 7: On December 18, 2009, a flash fire occurred during sampling at a company’s testing laboratory, resulting in one sampler being injured. The main cause of the accident was that the sampler at the original sampling port of the propylene tank would often get clogged after winter set in; the workshop removed the sampler and failed to reinstall it. At the time of the accident, the flow rate of the sample at the sampling port was regulated by a vent ball valve; there was no means of pressure reduction or throttling. The distance between the outlet for the propylene sample and the inlet of the sampling gas bag was significant, which led to substantial leakage of the propylene sample during collection. This resulted in the formation of flammable gases around the sampling port, which were ignited by static electricity. Problems identified: non-compliant sampling facilities, weak safety awareness, illegal operations... The above accident cases reveal that risk management during the sampling process has not received adequate attention; there are issues related to insufficient intrinsic safety, as well as a lack of safety awareness among operators, in addition to risky and illegal operations that pose safety hazards. First, the sampling facility is selected incorrectly or installed improperly, resulting in material leakage and causing poisoning or fire and explosion. During the production process, sampling of highly hazardous and extremely hazardous media, Class A flammable gases, liquefied hydrocarbons, and other such materials is not carried out using closed-loop sampling systems as required by Article 7.2.3 of the \"Code for Design of Metal Piping in Petrochemical Industries\" (SH 3012—2011). In some enterprises, single-valve control is used for sampling on-site; the sample is discharged there, or the sampler may fall off or break, resulting in a large leakage of toxic and flammable materials and causing poisoning or fires and explosions. Second, the sampling tools are substandard, generating static electricity that can lead to fires and explosions. The company has not established operating procedures for sampling tasks, and routine training is merely a formality. Sample collectors use equipment that generates static electricity, such as PVC pipes and plastic buckets, for sampling. During the sampling process, a large amount of static electricity accumulates and discharges, leading to fires and explosions in the containers. Third, the holding time for the receipt and dispatch of materials inside the container is insufficient. When sampling the material while it is in a filled or unloaded state, insufficient static electricity discharge can lead to electrostatic discharge, which in turn ignites the explosive gases inside the container and causes fires and explosions. Fourth, change management is inadequate; sampling points are added temporarily, with a lack of risk identification and control measures. On-site workers lack a strong safety awareness and do not use appropriate personal protective equipment; improper handling during sampling can lead to material leaks, resulting in poisoning or fires and explosions. Fifth, job permit management is inadequate, and safety training and education are merely a formality. Sampling personnel enter restricted spaces or areas near toxic gas leaks without authorization to take samples, resulting in poisoning or suffocation. Prevention recommendations: sealed sampling, prevention of static electricity, proper operating procedures… In line with relevant standards and regulations, it is recommended that enterprises take the following measures to manage the safety risks associated with on-site material sampling: (1) Regarding the selection and installation of sampling equipment, it is necessary to design sealed sampling facilities based on the properties of the materials. During the design phase, leakage risks must be thoroughly identified and assessed, and measures should be taken at the source to control such leaks and prevent them from occurring. For processes involving highly toxic and severe toxic substances, as well as storage tanks for liquids of toxicity grades I and II, if the toxicity level is determined to be moderate, high, or extremely high in accordance with the \"Classification of Hazards from Occupational Exposure to Toxic Substances\" (GBZ/T 230—2010), or if the fire hazard is classified as Class A flammable gases or Class A1, A2, and B1 flammable liquids according to the \"Fire Protection Design Code for Petrochemical Enterprises (2018 Edition)\」(GB 50160—2008) and the \"Fire Protection Code for Building Design (2018 Edition)\」(GB 50016—2014), sampling can be carried out using a closed sampling system in compliance with the \"Safety Requirements for Closed Sampling in Petrochemical Industries\" (T/CCSAS 003—2019); any condensate (residual liquid) should be discharged into a dedicated collection system in a sealed manner. Secondly, attention should be paid to the design and installation of the sampling system as well as the placement of the sampling ports; the samples collected must be representative. These sampling ports should not be located in dead zones of the pipeline. When the pressure of the medium at the sampling point is higher than 5.0 MPa (gauge), measures such as pressure regulators or pressure-reducing orifices should be used to reduce the pressure of the sampling medium. The sampling pipeline system should be installed in a location that is convenient for operation and easy to maintain; otherwise, platforms and guardrails must be provided. Sampling should be taken at lower temperatures and pressures of the process material; the temperature of the sampling medium must be controlled according to the properties of the material, with it generally being advisable for this temperature to be 40°C or less. For samples that need to be cooled, their temperature after cooling should be above the freezing point; when an open sampling system is used, medium of type B should be cooled below its flash point. When the temperature of the sample or the sample after cooling is above 60°C, it is advisable to use a heat-insulating, scald-proof sampling bottle ； When the sample temperature may drop below 0°C after sampling, it is advisable to use insulated, anti-freezing sampling bottles. Sampling pipes for combustible gases, liquefied hydrocarbons, and flammable liquids must not be led into the laboratory to prevent fire and explosion accidents resulting from leaks. (II) Regarding anti-static measures, it is recommended to comply with the relevant requirements of standards such as the \"Code for Design of Static Grounding in Petrochemical Industries\" (SH/T 3097—2017), the \"Design Standards for Automotive Loading and Unloading Facilities for Petrochemical Materials\" (SH/T 3221—2023), and the \"General Requirements for Preventing Static Electricity Accidents\" (GB 12158—2024). First, one set of equipment for eliminating static electricity from the human body should be installed 1.5 meters away on each side of the sampling port (oil measurement port) on the tank roof platform; such equipment must be electrically connected to the tank body and grounded, and tools such as sampling ropes and level gauges should be connected to this equipment. Secondly, anti-static devices should be installed at the locations near the equipment used for loading and unloading materials, and the distance between these devices and the loading/unloading ports should be no less than 1.5 meters. Third, no on-site operations such as sampling, measurement, or temperature testing should be carried out while the equipment is in operation for filling, circulating, or mixing. After the device stops operating, it should be left to rest for a certain period of time before the aforementioned operations can be carried out; the required resting time should be determined based on the liquid’s conductivity and the volume of the container, in order to establish a minimum resting time. For oil tankers, the standing time should be no less than 5 minutes. Fourth, samplers, thermometers, and gauges made of metal should be grounded during operation. Ropes and dipsticks made of synthetic materials used in equipment such as samplers, thermometers, and gauges should be made of electrostatic subconductors. When sampling, measuring, and taking temperature readings of oil products, one should not pull or lift them abruptly; the lifting speed should not exceed 0.5 m/s, and the lowering speed should not exceed 1 m/s. (III) In terms of on-site operation management, first, emphasis is placed on the safety management of the sampling process: corresponding sampling procedures are developed, boards indicating the sampling steps and precautions are installed at the sampling site, and training is provided for the personnel working there ； At the same time, it is necessary to determine whether a work permit is required for the sampling process; for sampling of materials with high risks, qualified supervisors must be assigned to oversee the operation on site. Secondly, emphasis should be placed on individual protective measures for workers. When working with high-temperature equipment or corrosive liquids or gases, which can cause skin burns, it is necessary to provide personal protective equipment that protects against burns. In situations where sampling takes place in enclosed spaces or environments with toxic gases, there is a risk of inhaling harmful gases; therefore, personal protective equipment that safeguards against poisoning and suffocation is required. Third, attention should be paid to the safety of the working environment. When sampling from high platforms, stairs, or bridges, inadequate protective facilities can lead to falling accidents. Severe weather conditions such as heavy rain, thunderstorms, and high temperatures may pose risks to sampling safety, and sampling should be suspended in such situations. Fourth, it is important to pay attention to the risks arising from changes. When sampling facilities need to be temporarily added or modified on-site due to production requirements, corresponding change management procedures must be implemented, relevant safety risks identified, and control measures put in place. For sampling materials whose operating temperature is above their auto-ignition point, special samplers should be used; sampling from the drain ports at the low points of pipes or equipment should not be employed. For temporary sampling points involving substances such as chlorine, phosgene, hydrogen sulfide, ammonia, and gas that can cause poisoning in humans, it is necessary to commission the design and installation of sealed sampling facilities, while also strengthening the safety management of sampling at these temporary sites. (IV) In terms of emergency response, first, emergency equipment must be provided. In accordance with the requirements set out in standards such as the \"Design Code for Occupational Safety and Health in Petrochemical Enterprises\" (SH/T 3047—2021) and the \"Design Code for Safety and Health in Chemical Enterprises\" (HG 20571—2014), accident handling devices and emergency protection facilities are designed based on the toxicity and hazards of the materials involved. In areas where exposure to irritating toxins, highly corrosive substances, or toxins that can be absorbed through the skin is possible during production, emergency shower stations and eye wash stations should be installed. The location of emergency showers or eyewash stations should be such that personnel can reach them within 10 seconds in the event of an accident, and they should be no more than 15 meters away from the relevant equipment. They must be on the same level as the area where hazardous operations take place, with no obstacles in between. Secondly, it is necessary to develop emergency plans and conduct drills. Based on the characteristics of the materials being sampled and the conditions of the work site, emergency plans should be formulated, along with on-site response procedures. Relevant personnel should be trained through drills so that they can respond effectively in case of emergencies, thereby preventing accidents from developing.