When filling LNG storage tanks, it is necessary to pay attention to regular inspection work

【1】 When filling low-temperature storage tanks, attention should be paid to safety management before filling: When starting to handle sales procedures for users, sales personnel for low-temperature liquids should: 1. Before starting to handle sales procedures for users, sales personnel should first conduct safety inspections on the user's tank trucks to eliminate potential accidents before filling. 2. Notify the laboratory technician to conduct a test on the oxygen purity inside the oxygen tanker, confirming the original filling medium and oxygen purity inside the tanker. The laboratory test results shall be submitted to the filling station. If they meet the requirements, filling shall be arranged. If they do not meet the requirements, filling shall not be arranged. After replacement treatment, re inspection and confirmation shall be carried out. 3. Inspect the necessary documents and information that users must bring with their car tanker, including: a. Car tanker usage certificate. b. Motor vehicle driving license and tanker driving permit. c. Escort certificate. d. Copy of the regular inspection report for the tanker truck. e. The correspondence table between the indication scale of the liquid level gauge and the volume. f. Run inspection records. g. Loading and unloading records of tanker trucks. 4. Inspect the paint color, lettering, and markings of the user's car tanker. The inspection items are: a. Tank color b. Words and handwriting c. Circular color band d. Graphic markings e. Dangerous goods markings f. Whether the filling hose of the tanker is damaged or leaking. 5. Strictly implement the relevant requirements of the "Safety Supervision Regulations for Liquefied Gas Tank Cars". If it does not meet the filling conditions, the filling unit shall not fill it. 6. Make all necessary preparations before filling to create a favorable environment for Anran filling. a. After passing the security check, the tanker truck should follow the designated route and drive at low speed to enter the filling station. b. After the tanker enters the workstation, the engine is turned off and the handbrake is used for braking. If there is a possibility of sliding, a slider should be added. c. Close the surrounding roads and hang warning signs, prohibiting any motor vehicles from passing through. d. Hang a one-to-one secure grounding wire. e. There shall be no flammable or explosive materials in the filling site and tank truck operation box. f. Connect the filling exhaust emission device to recover the residual gas in the tank. If it cannot be recovered, it should be released from high altitude and not discharged to the ground. g. Clean and degrease valve joints and hoses with carbon tetrachloride for oxygenation. h. When connecting the filling hose, it is strictly prohibited to use tools that are prone to sparking to strike. i. The filling personnel should wear anti-static (based on actual reports) work clothes and protective equipment. 7. Filling operations are prohibited in any of the following situations: a. During thunderstorms; b， When there is an open flame nearby; c. When there is maintenance work nearby; d. When discharging liquid oxygen from air separation; e. When the pressure inside the low-temperature storage tank is abnormal; f. When there is poor lighting at night; 2、 Safe management of the filling process: Implement safety monitoring throughout the entire process to confirm that the filling operation is safe and accident free. 1. Filling personnel and operators must stick to their posts and not leave the site. 2. The filling operation should be carried out slowly, and the cooling of the filling pipeline should be slow and uniform. 3. During the filling period, the car engine shall not be started, vehicle maintenance shall not be carried out, and walkie talkies, mobile phones, etc. shall not be used. 4. Filling personnel should regularly observe the pressure inside the tank, check the condition of each part, and promptly handle any abnormalities found. 5. The filling capacity of tank trucks shall not exceed the allowed larger filling capacity. 3、 After filling, Anran Management should promptly close the filling valve, discharge residual liquid and pressure from the pipe, and remove the connecting hose. 2. Check the compactness of the tanker. 3. Only after confirming that the oxygen content in the air on site is qualified, can the tanker truck leave. 4. Carefully keep filling records, which should be true, accurate, and traceable. 4. Precautions during operation: 1. The pressure inside the storage tank should not exceed its higher working pressure during operation. Operators should strictly follow the operating procedures. Check whether the Anran accessories are intact and whether the opening and closing positions of each valve are correct. 2. The opening and closing of the valve should be slow to prevent it from being too fast or too strong. The valve should not be tightened too tightly to avoid damaging the valve seal or artificially reducing the valve life. If the valve cannot be tightened, it should not be forcefully opened or closed. Generally, the moisture in the air of the valve stem freezes at low temperatures, and it should be poured with hot water before loosening. It is strictly prohibited to use a hammer, fire or electric heating. 3. Suitable protective equipment should be worn during operation to prevent skin contact with low-temperature liquids. Wear a safety helmet to prevent leakage of the pipeline above the head. 4. When loading and unloading low-temperature liquids, care should be taken not to splash or overflow them. Skin and eyes that may come into contact with liquids or cold pipelines, cold equipment, and cold gases should be protected. The arms should be protected by easily removable clean insulated long sleeves. The pant legs are included on the outside or above the shoes to avoid splashing liquid skin. 5. At the end of transportation, the liquid in the delivery pipeline should be discharged to prevent gasification overpressure. The outlet valve of the booster should be closed after the liquid in the booster has gasified completely. 6. When there is obvious large-scale sweating on the outer surface of the storage tank, it should be stopped from use and the cause should be identified in a timely manner. 7. If abnormal pressure rise is found in the storage tank, the liquid should be discharged as soon as possible and maintenance should be carried out. 8. When the storage tank is not in use for a short period of time, do not drain all the liquid in the tank. Leave 20% of the liquid weight according to the length of the interruption time to reduce evaporation loss when refilling. 9. In addition to being familiar with the characteristics of low-temperature liquids, operators also need to master explosion-proof (based on actual reports), safety technology, and fire safety regulations. 【2】 The regular inspection of low-temperature storage tanks is determined after using natural growth gas storage tanks for a period of time, even if we do not notice any abnormalities in the local area. When inspecting and repairing low-temperature storage tanks, it is necessary to pay attention to some key points. The following are the parts that need to be checked when inspecting low-temperature storage tanks: regular inspection of low-temperature storage tanks includes analysis of corrosion types, corrosion, weld conditions, and corrosion products. Microscopic examination, flaw detection, anti-corrosion (based on actual reports) of the aging level, cracking, withering status, wear and other damage phenomena of the layer. We should gradually select condition monitoring instruments to monitor the corrosion status of low-temperature storage tanks in operation, laying a foundation for predicting repairs. Make detailed records of the viewing results (in duplicate), and have them archived and stored by the mobile department and workshop. The annual review will be suspended on the basis of self inspection by each unit. When inspecting low-temperature storage tanks, 1-2 units of the same type of equipment should be randomly inspected based on their quantity. Take two sections of the same type of pipeline on the main or branch pipeline for inspection. External inspection: Check whether the anti-corrosion (based on actual reports) layer, insulation layer, and equipment nameplate of the storage tank are intact, and whether the Anran accessories and control devices are diverse, sensitive, and excellent; Whether there are cracks, deformations, local overheating and other phenomena on the outer surface; Check for leaks in the weld seams and pressure components, ensure that there are no missing fastening bolts, and check for any abnormal conditions such as sinking or tilting of the foundation. Internal inspection: Check for corrosive wear on the internal and external surfaces and manhole receiving tanks, and for cracks in welds, transition zones of heads, or other stress concentration areas; When there is corrosion or other phenomena on the inner and outer surfaces of the tank, multiple wall thickness measurements should be taken at suspected locations. If the measured wall thickness is smaller than the planned smaller wall thickness, the strength should be re evaluated, and suggestions should be made on whether it can be used continuously and whether higher working pressures are allowed; When there are defects such as decarburization, stress corrosion, intergranular corrosion, and fatigue cracks on the inner wall of the tank, metallographic examination and surface hardness measurement should be carried out, and an inspection report should be submitted.