[Work Safety Exposure Platform] Inadequate risk control for the tank floating disk hitting the bottom, and imperfect inspection and maintenance plans

Thread Content

Recently, the State Council Safety Committee organized 20 comprehensive inspection teams to conduct random inspections on the work related to the special rectification of major safety hazards and supervision inspections in 31 provinces (autonomous regions, municipalities directly under the Central Government) as well as the Xinjiang Production and Construction Corps. From February 21st to 25th, reporters from Nan Du and N Video accompanied Group 13 of the comprehensive inspection team on a mission to Suzhou and Huai’an in Jiangsu Province, where they conducted both open and secret inspections of various local enterprises in the transportation, industrial and trade, and hazardous chemicals sectors. They found that some enterprises issued permits for hot work in violation of regulations, that there were flaws in their monitoring and alarm systems, and that safety training and assessment procedures were not properly enforced. The risk management for the tank float sinking to the bottom is inadequate, and the inspection and maintenance plans are insufficient. For key sectors such as those involving hazardous chemicals, the inspection team also carried out secret inspections. On February 22, the inspection team made a surprise visit to Taicang Yanghong Petrochemical Co., Ltd. A member of the inspection team told a Nandu reporter that the choice of this company was made just before departure. Including the experts, no one knew the next stop at the time of boarding and setting off. Taicang Yanghong Petrochemical Co., Ltd. is located near the Yangtze River and has a 80,000-ton capacity terminal. It features 77 storage tanks and specializes in providing storage services for petrochemical products. It is the largest methanol storage facility in China, as well as a designated delivery site for methanol and ethylene glycol futures. The experts from the inspection team first went to the enterprise’s control room. After reviewing the Safety Instrumented System (SIS) and alarm records, the experts found that the floating roof of tanks such as T608 had fallen to the bottom on multiple occasions. When the liquid level in the storage tank is below the supporting height, the floating disk support settles on the bottom of the tank, a condition known as the floating disk hitting the bottom. The on-site staff explained, “Our goods are stored in the customer’s warehouse; they want to empty the tank completely, so we need to apply for the floating floor to be lowered.” ”The float level of the T608 storage tank is 1.8 meters below the bottom; when the liquid level drops to 1.9 meters, the low liquid level interlock is activated. At this point, if the discharge floating disk continues to sink to the bottom, it is necessary to obtain approval to disable the interlock. Subsequently, the staff member brought out the relevant approval forms. However, experts have found that the safety measures outlined in the approval forms cannot completely eliminate risks. “There is a lack of control measures for risks such as feed rate, and this aspect has not received sufficient attention. ”Experts explained to reporters from Nan Du that during normal operation, once the floating disk settles at the bottom, an air space is formed between the floating disk and the oil surface. When the flow rate of the material is too high, static electricity accumulating at the outlet of the material pipeline can easily lead to explosions and fires. On January 15, an explosion and fire occurred at the alkylation unit of Liaoning Panjin Haoye Chemical Co., Ltd. during maintenance work, resulting in 13 deaths and 35 injuries. The State Council Safety Committee has placed the investigation and handling of this accident under supervised oversight. The Office of the State Council’s Safety Committee stated that it is necessary to carry out special inspections and rectifications to address the issue of chemical processing units and equipment operating while faulty; preventive measures should be strengthened for potential hazards in key areas, and these hazards should be addressed promptly. “This accident was related to a pipeline rupture and material leakage, most likely caused by the thinning of the pipeline walls after prolonged operation; such issues should be detected and addressed promptly during preventive maintenance. ”During this inspection, the experts specifically inquired about the maintenance plan. The staff said that the safety accessories of the storage tanks are inspected every month, but the company’s equipment and facility maintenance plan for 2023 does not mention regular inspections of the tank bodies and their safety accessories.