4.1 Selection of Design Unit for Liquefied Gas Storage Tank Engineering: The selection of a design unit for the liquefied gas storage tank system engineering should be handled by the project organization department of the provincial (city, district) companies. It should be chosen from the shortlisted design institutes, and the supervisor's signature of approval is required. The design unit should be qualified with petrochemical engineering design资质 and industrial pipeline (GC2) design资质. 4.2 Site Survey: 4.2.1 The site survey should be organized by the project organization department of the provincial (city, district) companies, involving the construction, pipeline, quality safety departments of the branch company where the gas station is located, as well as the design institute. 4.2.2 For the investigation and survey of the gas station, the layout and burial depth of the existing underground pipelines and cable laying should be understood. For stations that cannot provide site pipeline data, pipeline detection technology should be used to determine the existing process, electrical, and water supply and drainage pipelines. 4.2.3 The construction department of the branch company where the gas station is located should propose suggestions for the scope of renovation, renovation methods (unloading oil vapor recovery system, refueling oil vapor recovery system [dispersed, centralized], oil and gas emission treatment device), and related equipment facilities renovation, following the principles of economic and practicality and relevant local government requirements. After approval by the supervisor and the project organization department of the provincial (city, district) company, the design unit will base the design on these suggestions. 4.3 Design Proposal: 4.3.1 The design proposal submitted by the design institute should include technical documents such as the general layout, oil vapor recovery process diagram, and main equipment and material list. 4.3.2 The design proposal should be reported to the project organization department of the provincial (city, district) company, which will organize the pipeline, quality safety departments, and construction personnel of the branch company where the gas station is located, as well as the design institute, for proposal review, and the supervisor's approval is required. 4.4 Construction Drawing Design: 4.4.1 Equipment selection: The project organization department of the provincial (city, district) companies will provide a list of pre-qualified suppliers for oil vapor recovery equipment. The design institute will select the relevant equipment based on this list. The selection should follow the principles of safety, reliability, technical advancement, economic practicality, and compliance with emission standards, and should use products that are easy to install, convenient, and require minimal on-site modification. The following points should also be noted: 4.4.1.2 It is preferable to select equipment from the same manufacturer in the same area for easier after-sales service. 4.4.1.2 Gas stations with an annual gasoline refueling volume of more than 3,000 tons and more than 10 gasoline guns should use a centralized refueling oil vapor recovery system; others should use a dispersed refueling oil vapor recovery system. 4.4.1.3 Different types of oil vapor recovery technology and equipment should be selected based on the internal space of the fuel dispenser. For example, a secondary recovery dispersed vacuum pump should use a smaller power, which can be driven by the existing power supply of the fuel dispenser, and it is not advisable to lay additional power cables. 4.4.1.4 The oil and gas emission treatment device should be selected based on the surrounding environment, site size, and business volume of the gas station. The maximum oil and gas treatment capacity of the emission treatment device should be 10% to 20% of the maximum refueling volume. 4.4.2 Construction drawing design: 4.4.2.1 The design institute will carry out construction drawing design based on the approved design proposal. 4.4.2.2 For the liquefied gas storage tank pipeline, seamless steel pipes that comply with the current national standard "Seamless Steel Tubes for Fluid Transportation" GB/T8163 should be used. The design pressure of the oil product pipeline should not be less than 0.6 MPa, and the design pressure of the oil vapor recovery pipeline should not be less than 0.13 MPa. It is not advisable to use thermoplastic plastic pipelines or other flexible material pipelines.
Liquefied gas tanks are pressure vessels, and the national requirement is for an annual inspection (the recommended service life for simple pressure vessels is 10 years). Since inspections are conducted, there are products that pass or fail. Generally, due to improper usage procedures or inadequate maintenance, businesses may find their liquefied gas tanks fail inspection, necessitating mandatory scrapping. As liquefied gas tanks are special equipment, scrapping requires a specific process. Compressor liquefied gas tanks are often considered safe special equipment, but if any aspect of manufacturing, design, installation, or usage management is not standardized, accumulated hazards could lead to explosion accidents or even more severe consequences. Therefore, we must follow the operating procedures for our compressor liquefied gas tanks, avoid shortcuts, and never purchase inexpensive tanks from unqualified manufacturers. Tanks with a volume of 1 cubic meter containing 10 kg or less are classified as simple pressure vessels and do not require inspection. According to national regulations, they are exempt from inspection for 7 years from the date of manufacture on the label, but this exemption only applies to the tank itself.
