How often should benzene storage tanks be inspected?

The regular inspections of periodic storage tanks are divided into external inspections, internal and external inspections, and comprehensive inspections. The inspection cycle should be determined as appropriate based on the technical condition of the equipment and its operating conditions; however, external inspections must be carried out at least once a year, internal and external inspections at least once every 3 years, and comprehensive inspections at least once every 6 years. If the storage tank has been in use for 15 years, internal and external inspections should be carried out every two years ； If the service life has reached 20 years, internal and external inspections should be carried out at least once a year. For storage tanks that have undergone regular inspections, the inspector prepares an inspection report indicating whether the tank can continue to be used or whether special monitoring measures are required. The inspection report shall be filed in the technical archive of the storage tank.

What was mentioned upstairs is the mobile tank, right! Our factory has several fixed tanks, which have not been inspected. Phenol is a hazardous chemical of Category 6 and is not listed among the highly toxic chemicals; tanks containing highly toxic substances are required to be inspected! ! !

Are there any testing standards for highly toxic substances?

If this tank is considered a pressure vessel, there are corresponding inspection rules; one can refer to the relevant requirements of TSG R7001-2004 \"Regulations for Periodic Inspection of Pressure Vessels\". These regulations cover the aspects related to periodic inspections (annual inspections, comprehensive inspections, pressure tests), as well as the required inspection intervals (3 years, 6 years, 9 years, 12 years, etc.). If this tank is not a pressure vessel, it seems there are no relevant **specifications or standards**, but large companies (such as Sinopec and CNPC) generally have their own corporate standards and regulations ； Generally, large low-pressure storage tanks (including those holding extremely hazardous or highly dangerous substances, as well as flammable substances) require a tank cleaning inspection at least once every 6 years. For reference!

It’s not a pressure vessel; at normal temperature and pressure, it is simply used to store benzene, with a capacity of 50 cubic meters. The main thing is to find the standards or regulations that apply to it

According to the \"Regulations on Safety Supervision of Pressure Vessels\", 1. A pressure vessel falls under Category III in any of the following situations: (1) High-pressure vessels； (2) Medium-pressure vessels (only for media with extremely high and high toxicity) ； (3) Medium-pressure storage vessels (only for flammable or moderately hazardous media, with a PV product greater than 10 Mpa·m3); (4) Medium-pressure reaction vessels (only for flammable or moderately hazardous media, with a PV product greater than or equal to 0.5 Mpa·m3); (5) Low-pressure vessels (for extremely hazardous or highly hazardous media, with a PV product greater than or equal to 0.2 Mpa·m3) ； (6) High-pressure and medium-pressure shell-and-tube waste heat boilers ； (Note 4) (7) Medium-pressure glass-lined pressure vessels ； (8) Pressure vessels manufactured from materials with a high strength level (meaning that the minimum specified value for tensile strength in the relevant standards is 540 Mpa or higher) ； (9) Mobile pressure vessels, including railway tank cars (for liquefied gases and cryogenic liquids), tank trucks, and tank containers (for liquefied gases and cryogenic liquids), etc ； (10) Spherical storage tanks (volume greater than or equal to 50 m3) ； (11) Storage vessels for cryogenic liquids (volume greater than 5 m3). 2. A pressure vessel falls under Category II in any of the following circumstances (except as specified in Paragraph 1 of this article): (1) Medium-pressure vessels ； (2) Low-pressure vessels (media with extreme and high toxicity levels) ； (3) Low-pressure reaction vessels and low-pressure storage vessels (for flammable media or media with moderate toxicity) ； (4) Low-pressure shell-and-tube waste heat boiler ； (5) Low-pressure glass-lined pressure (6) Pressure vessels. 3. Low-pressure vessels are classified as Class 1 pressure vessels (except as provided in paragraphs 1 and 2 of this article). Article 132: The regular inspections of pressure vessels are divided into: 1. External inspection: This refers to periodic on-site inspections of pressure vessels while they are in use, to be carried out at least once a year. External inspections can be carried out by pressure vessel inspectors from qualified inspection agencies, or by specialized personnel in pressure vessel management from the using units, as approved by the safety supervision authorities. 2. Internal and external inspections: refer to the inspections carried out when a pressure vessel in use is shut down. Internal and external inspections shall be carried out by qualified pressure vessel inspectors from the inspection agency. Its inspection cycle is divided as follows: (1) For those with a safety status rating of 1 or 2, at least once every six years ； (2) For those with a safety status level of 3, at least once every 3 years. Article 133: The general period for the first internal and external inspection upon commissioning is 3 years. The subsequent internal and external inspection schedules shall be determined by the inspection agency in consultation with the user unit, based on the results of previous internal and external inspections, and then submitted to the local safety supervision authority for record-keeping. For pressure vessels that fall under any of the following conditions, the external inspection interval should be reduced accordingly: 1) when it is unclear how the medium corrodes the material of the pressure vessel, or when the corrosion rate of the medium on the material is greater than 0.25 mm/year, or when the corrosion data determined by the designer does not match the actual situation. 2. Poor surface quality of the material or internal defects, poor weldability of the material, or multiple revisions during manufacturing. 3. In environments with harsh operating conditions or where the hydrogen sulfide and sulfur content in the medium is high (generally referring to levels above 100 mg/L). 4. Those that have been in use for over 20 years, and which, after technical assessment or as confirmed by inspectors, cannot be used safely within a normal inspection cycle. 5. Those that have been out of use for more than two or three years. 6. Continued use after passing the defect safety assessment. 7. Those that frequently change the medium used (such as printing and dyeing machines). 8. Glass-lined equipment. 9. Spherical storage tanks (manufactured from materials with σb≥540 Mpa; inspection inside the tank should be carried out one year after operation). 10. For media that are liquefied petroleum gas and have a tendency to stress corrosion due to hydrogen embrittlement, internal and external inspections shall be carried out annually or as needed. 11. For papermaking processes using the \"immonium method\" and without anti-corrosion measures, internal and external inspections should be carried out at least once a year, or more frequently as required by actual conditions. Article 134: For pressure vessels with a safety status rating of 1 or 2, the internal and external inspection intervals may be appropriately extended under one of the following circumstances: 1. If the non-metallic lining is in good condition, the inspection interval may be extended, but not for more than 9 years. 2. For pressure vessels in which the corrosion rate of the medium on the material is below 0.1 mm/year (based on actual measurement data), and which have a reliable corrosion-resistant metal lining (composite steel plate) or a thermal-sprayed metal coating (aluminum powder or stainless steel powder), the inspection interval can be extended if internal and external inspections show minor corrosion or that the lining is in good condition; however, this extension shall not exceed 12 years. 3. For reaction vessels equipped with catalysts and large pressure vessels containing fillers, the inspection cycle is determined through consultation among the user unit, the design unit, and the inspection unit, based on the design drawings and actual usage conditions, and shall be filed with the local safety supervision agency. Appendix 6: Classification and Explanation of the Safety Status Grades for Pressure Vessels. Based on the safety status of pressure vessels, new pressure vessels are classified into three grades: 1, 2, and 3, while in-use pressure vessels are classified into four grades: 2, 3, 4, and 5. The classification principles for each grade are as follows: Grade 1: Pressure vessels come with complete technical documentation at the time of manufacture ； The design and manufacturing quality meet the requirements of relevant regulations and standards ； It can be used safely under design conditions within the specified regular inspection period. Level 2: (1) New pressure vessels: Complete technical documentation at the time of manufacture ； The design and manufacturing quality generally meet the relevant regulations and requirements, but there are certain defects that do not pose a safety risk and are difficult to correct; approval from the design entity, the user entity, and the local safety supervision authority was obtained at the time of shipment ； It can be used safely under the operating conditions specified in the design within the prescribed periodic inspection cycle. (2) In-service pressure vessels: Technical documentation is basically complete ； The design and manufacturing quality generally meet the requirements of relevant regulations and standards ； According to the inspection report, there are some general defects that do not pose a safety risk and are not easy to repair ； It can be used safely under specified operating conditions within the prescribed regular inspection cycle. Level 3: (1) New pressure vessels: The technical documentation provided at the time of manufacture is basically complete ； The main materials, strength, and structure generally meet the requirements of relevant regulations and standards ； However, any issues or defects related to non-compliance with regulations and standards that existed during manufacturing were resolved with the approval of the design entity, the user entity, and the safety supervision authority in the location of the user entity at the time of shipment ； It can be used safely under the operating conditions specified in the design within the prescribed periodic inspection cycle. (2) In-service pressure vessels: Insufficient technical documentation ； The main materials, strength, and structure generally meet the requirements of relevant regulations and standards ； Certain issues or defects existing during manufacturing that are not in compliance with regulations and standards; the welds have volumetric defects exceeding the allowable limits. According to the inspection report, no progression or expansion of such defects was detected ； Its inspection report confirms that it can be used safely within the specified regular inspection intervals and under the prescribed operating conditions. Level 4: The main material does not meet the relevant regulations, or its identity is unknown; or although the correct material has been selected, it already shows signs of aging ； The main structure has serious defects that violate relevant regulations and standards; however, its strength, as verified, still meets the required requirements ； There are linear defects in the welding quality ； According to the inspection report, no defects were found to have developed or worsened due to usage factors ； Defects such as corrosion, wear, damage, and deformation occurred during use, and the inspection report determined that it cannot be used safely under specified operating conditions or within a normal inspection period. Appropriate measures must be taken for repair and treatment to raise the safety level; otherwise, it can only be used under limited conditions for short-term monitoring. Grade 5: Pressure vessels manufactured by enterprises without a manufacturing license or by enterprises that are unable to prove that the original manufacturer holds such a license ； Pressure vessels with severe defects that are unreparable or difficult to repair, have no value for repair, or cannot ensure safe use even after repair, should be declared obsolete and must not be used as pressure-bearing equipment any longer. Note: 1. The defects mentioned in the safety condition level represent the final state of that pressure vessel at the time of its manufacture. If the defect has been eliminated, the safety classification of the pressure vessel is determined based on its condition after elimination. 2. In cases where the technical documentation is incomplete, the original manufacturer or testing agency shall, in accordance with relevant regulations, complete the documentation after conducting inspections and verifications; if a conclusion can be drawn in the test report, then it can be treated as having basically complete technical documentation. If it cannot be determined that the original manufacturer possesses the necessary manufacturing qualifications, supplementary technical documents cannot be approved through inspection and verification. 3. For the problems and defects mentioned in the safety condition grade, as long as it is confirmed that one of the most severe conditions applies, the safety condition grade of the pressure vessel can be determined based on its nature.