Asphalt storage tanks operate under high temperature all year round, and the stored liquid asphalt is flammable, viscous and accompanied by volatile harmful gas. Coupled with the supporting heating system, pipelines and electrical facilities, the whole tank area involves multiple safety risks such as fire, scald, poisoning, leakage and mechanical failure. Standardizing safe operation procedures and implementing scientific daily maintenance are essential to eliminate hidden dangers, ensure continuous and stable operation of equipment and extend the service life of storage tanks. This article systematically sorts out the whole-process safe operation specifications of asphalt storage tanks, as well as detailed daily inspection, maintenance, regular overhaul and fault handling requirements for on-site management reference.

Before starting any operation on the asphalt storage tank, operators must complete pre-operation preparation and safety confirmation. All staff need to receive professional safety training, master the physical and chemical characteristics of asphalt, operating rules of heating and temperature control systems, and correct use of fire-fighting and protective equipment. Before entering the tank area or conducting on-site work, check whether personal protective equipment such as high-temperature resistant gloves, protective goggles, anti-slip work clothes and gas masks are intact and wear them in place. Strictly implement the access management system of the tank area. It is forbidden for irrelevant personnel to enter at will. All vehicles entering the tank area must be equipped with fire arresters, and smoking, open flame operation and cell phone use are completely prohibited within the whole tank area. Before feeding, discharging or starting the heating system, inspect key equipment including tank body, valves, connecting pipelines, heating coils, temperature sensors and pressure gauges to confirm no leakage, blockage or instrument failure, and verify that all interlocking protection devices are in normal working state.

Standard operation during feeding and discharging is the key link to prevent running, overflowing and leakage of asphalt. When receiving raw asphalt, control the feeding speed stably and do not fill the tank excessively. Strictly follow the liquid level limit standard, and reserve enough safety space at the top of the tank to avoid asphalt overflow caused by liquid level expansion after heating. Observe the liquid level gauge and real-time temperature data during the whole feeding process. Once abnormal liquid level fluctuation or pipeline vibration occurs, slow down or stop feeding immediately for inspection. When discharging asphalt, gradually open the outlet valve and keep the flow stable to prevent high-temperature asphalt from splashing and causing scald accidents. It is forbidden to start large-flow discharging when the asphalt temperature is too low and the viscosity is too high, so as to avoid excessive load on the pipeline and pump body and pipeline rupture. After feeding and discharging are completed, close each valve in sequence, purge the residual asphalt in the short pipeline, and make complete operation records including operation time, asphalt quantity, initial and final temperature and liquid level data.

Temperature control and heating system operation must comply with strict specifications to prevent asphalt aging, local overheating and equipment damage. The storage temperature of different grades of asphalt shall be controlled within the designated range, generally maintained between 130℃ and 160℃. Do not blindly raise the temperature. Long-term ultra-high temperature will accelerate asphalt aging, increase flue gas volatilization, and also cause excessive load on heating coils and insulation layers. When starting the heating system, follow the step-by-step heating principle, and do not heat up rapidly in a short time to prevent uneven thermal expansion of the tank body and welding seam cracks. For steam heating and heat conduction oil heating systems, regularly check the medium pressure and pipeline flow, and strictly prohibit overpressure operation. For electric heating equipment, inspect the circuit, electric heating elements and leakage protection devices before startup. Once abnormal temperature rise, alarm or equipment noise is found during operation, cut off the power or heat source immediately, stop the system for troubleshooting, and do not run the equipment with faults. In cold seasons, keep the heating and heat tracing system running normally to prevent asphalt and heat medium from solidifying and blocking pipelines.

Confined space operation and internal maintenance of asphalt tanks belong to high-risk operations and must implement special approval procedures. Before entering the tank for cleaning, overhaul or welding construction, stop all feeding and discharging work, cut off all connected pipelines and electrical equipment, and implement double locking and power failure isolation. Fully ventilate the interior of the tank for more than a specified time, and use professional gas detectors to test the concentration of flammable gas, toxic gas and oxygen content inside the tank. Operation can only be carried out after all indicators reach the safety standard. A special person must be assigned to supervise outside the tank throughout the process, and the supervisor shall not leave the post arbitrarily. Operators inside the tank shall wear air breathing apparatus and high-temperature resistant protective clothing, and set up safety ropes for emergency rescue. It is forbidden to carry out open flame welding, cutting and other hot work in the tank before gas detection and ventilation are qualified. After the internal operation is completed, count the personnel and tools to ensure no one or sundries are left inside the tank, and then close the manhole.

Fire prevention, explosion protection and exhaust gas management run through the daily operation of the tank area. Volatile asphalt flue gas is flammable and toxic. Keep the exhaust and ventilation devices of the tank in normal operation for a long time to reduce the gas concentration in the upper space of the tank. Regularly check the sealing performance of the tank roof, manhole and each access port to prevent a large amount of flue gas from escaping outward. The fire-fighting facilities in the tank area such as fire extinguishers, fire hydrants and fire sand pits shall be placed in fixed positions and kept intact at all times. Check the validity of fire-fighting equipment every month. The fire isolation zone around the tank shall be kept unobstructed, and no combustible materials are allowed to be stacked. All electrical equipment in the tank area adopts explosion-proof models, and regularly inspect explosion-proof joints, wiring ports and grounding devices to eliminate electric spark hidden dangers. In case of flue gas concentration exceeding the limit or local asphalt combustion, cut off all heat sources and power supplies first, and use matching fire-fighting materials to put out the fire. Do not splash water directly on high-temperature asphalt to prevent asphalt splashing and accident expansion.

Daily routine inspection is the foundation of equipment maintenance, which is divided into patrol inspection per shift, daily inspection and weekly comprehensive inspection. During each shift patrol, operators focus on checking the appearance of the tank body for deformation, paint peeling and rust spots; check all welding seams, flange connections and pipeline interfaces for asphalt leakage and seepage; monitor the indication of temperature gauges, liquid level gauges and pressure gauges to ensure the data is accurate and stable. Inspect the external thermal insulation layer and protective cover to find out damage, falling off and water seepage in a timely manner. Check the operation sound and temperature of heating furnaces, circulating pumps and other power equipment, and confirm that there is no abnormal vibration or oil leakage. For the drainage system at the bottom of the tank and the surrounding drainage ditches, clear accumulated water and dirt regularly to avoid long-term water soaking on the tank foundation and bottom plate. All inspection contents shall be recorded truthfully, and abnormal points shall be reported and disposed of immediately.

Regular maintenance and periodic overhaul are used to maintain the long-term performance of the storage tank. On the basis of daily inspection, conduct a comprehensive maintenance every month: fasten loose bolts of valves, platforms and escalators; replace aging gaskets and sealing parts; clean dust and sundries on the surface of instruments and electrical cabinets; test the sensitivity of alarm, interlock and protection devices. Every six months, inspect the anti-corrosion coating of the internal and external tank body, and carry out partial rust removal and repainting for rusted and peeled areas. Clean dirt and sludge at the bottom of the tank regularly according to the operating load, so as to prevent sediment from accumulating too much and affecting heating efficiency and asphalt quality. For heating coils and heat tracing pipelines, conduct scale removal and pressure testing regularly to ensure smooth medium circulation. Every year, organize a comprehensive overhaul of the whole tank area, including foundation settlement detection, overall stress inspection of the tank body, non-destructive testing of welding seams, performance calibration of all instruments and full function test of the fire-fighting system. Formulate overhaul plans in advance, implement safety isolation during construction, and make detailed overhaul archives after completion.

For common faults in operation, formulate standardized disposal plans. When local leakage occurs at welding seams or pipelines, stop the nearby heating device first, reduce the temperature properly, and carry out leakage remediation after the asphalt fluidity decreases. If the liquid level and temperature display are abnormal, check whether the sensor and connecting line are faulty, and replace the damaged parts in time. When the heating efficiency drops obviously, check whether the heating coil is blocked or scaled, and clean and dredge it as required. Once personnel contact high-temperature asphalt and cause scalding, or inhale harmful gas and feel unwell, transfer the injured person to a safe area immediately and carry out emergency treatment, and send them to hospital for medical treatment in time.

To sum up, the safe operation and daily maintenance of asphalt storage tanks are systematic work combining standardized operation, real-time inspection, regular maintenance and emergency disposal. All operating personnel must strictly abide by safety specifications, implement inspection and maintenance item by item, and eliminate various potential risks in the bud. Scientific management can not only ensure the personal safety of operators and the safe operation of equipment, but also reduce equipment failure rate and maintenance cost, and provide a reliable guarantee for the long-term and efficient operation of the entire asphalt storage and supply system.