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GB 19521.14-2004 Safety Code for Inspection of Small and Medium Pressure Vessels Used with Hazardous Goods – Scope: This standard specifies the requirements, sampling, performance testing, marking, and inspection rules for small and medium pressure vessels used with hazardous goods. This standard applies to the inspection of metal gas cylinders (hereinafter referred to as cylinders) filled with low-pressure liquefied gases or dissolved gases, which are used under normal ambient temperatures of -200°C to 60°C, at a working pressure not exceeding 2.43 MPa (gauge pressure), and with a water capacity of 25 L. 2 Normative reference documents The provisions in the following documents become provisions of this standard through reference to it. For reference documents dated, all subsequent amendment sheets (excluding corrections) or revised versions thereof are not applicable to this standard; however, parties reaching an agreement under this standard are encouraged to consider whether the latest versions of such documents can be used. For reference documents without a date, the latest version applies to this standard. GB/T 2828-1987 Sampling procedures for inspection by attributes – Sampling tables (applicable to inspections of continuous batches); GB 4351-1997 General technical requirements for portable fire extinguishers; GB/T 4857.3-1992 Packaging – Transport packaging – Method of test for static load stacking; GB/T 4857.5-1992 Packaging – Transport packaging – Method of test for drop impact; GB 5100-1994 Welded steel gas cylinders; GB 17268-1998 Industrial non-refillable welded steel gas cylinders; GB 19458-2004 Safety regulations for the testing of packaging of air-distributed dangerous goods – General provisions; United Nations Recommendations on the Transport of Dangerous Goods, Model Regulations (13th revised edition); 3 Terms and definitions: The terms and definitions established in GB 19458-2004, as well as the following terms and definitions, apply to this standard. 3.1 Inspection lot: Cylinders made of materials of the same grade, produced using the same manufacturing process, and having the same specifications and dimensions; this is simply referred to as a lot. 3.2 Low-pressure liquefied gases: Gases with a critical temperature higher than 70 ℃. 3.3 Soluble gases: Compressed gases that are dissolved in a solvent when the package is transported. 3.4 Working pressure: For cylinders filled with low-pressure liquefied gases, it refers to the pressure of the substance inside the cylinder at 60 °C, when filled according to the specified filling coefficient; for cylinders filled with dissolved gases, it refers to the pressure of the substance inside the cylinder at 60 °C, under the condition of a limited filling amount. 4 Requirements 4.1 General appearance requirements 4.1.1 Each small and medium-sized pressure vessel shall be provided with permanent markings and labels in accordance with the requirements specified in Chapter 7 of this standard. ICS C 66 Luban – National Standard of the People’s Republic of China (GB 19521.14-2004) Safety Code for the Inspection of Medium and Small Pressure Vessels Used for Hazardous Goods. Published on 2004-11-01; in force since then. Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China and the Standardization Administration of China. Preface: Chapters 4, 6, 7, and 8 of this standard are mandatory, while the remaining chapters are advisory in nature. This standard is not equivalent in terms of consistency with the United Nations’ Recommendations on the Transport of Dangerous Goods, Model Regulations (13th revised edition), and the International Maritime Organization’s (IMO) International Regulations for Safe Loading of Dangerous Goods, 2000 edition. Its technical content is consistent with those regulations, while the standard text format has been edited in accordance with GB/T 1.1-2000. This standard was proposed and taken under responsibility by the National Technical Committee for Standardization of Hazardous Chemicals Management (SAC/TC 251). The entity responsible for drafting this standard: **Center Laboratory for Hazardous Goods, General Administration of Quality Supervision, Inspection and Quarantine.** Units involved in the drafting of this standard: Tianjin Entry-Exit Inspection and Quarantine Bureau, Asia-Pacific Dangerous Goods Association, Jiangnan University. Main drafters of this standard: Wang Libing, Shang Wei, Zhao Haoli Bao, Hu Xingong, Zheng Qun, Lv Gang. This standard is being formulated for the first time. According to GB 19521.14-2004 4.1.2, the design, manufacture, testing, and installation of small and medium-sized pressure vessels and their sealing devices must ensure a rational structure, good protective properties, and the ability to withstand the risks associated with normal transportation conditions. 4.1.3 The materials of small and medium-sized pressure vessels and their sealing devices that come into direct contact with dangerous goods must not undergo any reaction that could affect their strength in relation to the dangerous goods they are intended to hold. 4.1.4 The manufacturing of medium and small pressure vessels shall comply with the requirements of Chapter 6.2 of the United Nations Recommendations on the Transport of Dangerous Goods, Model Regulations, 13th revised edition. 4.2 Performance test requirements 4.2.1 Vertical impact drop test: The valve of the sample bottle shall show no leaks, the protective device shall be in good condition with no fractures; if the protective device is deformed but still retains its protective function, it is also considered acceptable. 4.2.2 Hydrostatic test: The sample bottle shows no macroscopic deformation, nor any defects that could affect its strength such as leakage. 4.2.3 Airtightness test: The sample bottle shows no macroscopic deformation and no leakage. 4.2.4 Stack testing: The sample bottle does not collapse, and there is no cracking or leakage. 4.2.5 Temperature resistance test: The sample bottle shows no leakage or other abnormalities. 4.2.6 Hydrostatic burst test: The hydrostatic burst test pressure for steel cylinders shall be not less than 1.8 times the test pressure, and the rupture of the cylinder shall occur in its cylindrical portion, without cracking first at the welds. If the crack first occurs on the weld or on the head, or in any opening, reinforcement area, fitting location, or in a direction other than the longitudinal direction of the cylinder body, then the hydraulic pressure burst test of that gas cylinder is considered failed. Sampling 1 Sampling rules: 1.1 For general appearance inspection, sampling is carried out in accordance with GB/T 2828-1987 using the normal inspection sampling scheme at the general inspection level Q; the number of samples to be taken is shown in Table 1. 1.2 The number of samples for performance tests is indicated in Table 2. 1.3, Provided that the test results are not affected, it is permissible to conduct multiple tests on the same sample. Table 1: Unit is pieces. Range of batch sizes and number of samples to be tested: 1–8: 2 samples; 9–15: 3 samples; 16–25: 5 samples; 26–50: 8 samples; 51–90: 13 samples; 91–150: 20 samples; 151–280: 32 samples; 281–500: 50 samples; 501–1,000: 80 samples; 1,001–2,000: 125 samples; 2,001–5,000: 200 samples. Table 2: Unit is pieces. Test items and number of test samples: Vertical impact and drop test: 6 samples; Hydrostatic test: 3 samples; Airtightness test: 3 samples; Stacking test: 3 samples; Temperature resistance test: 6 samples; Water pressure burst test: 3 samples; Performance test: 1 sample. Preparation of test samples: 1.1 For the vertical impact and drop test, the test container is filled with water as a substitute for the test material, to the maximum capacity of the container, without any internal pressure, with the valve tightened. 1.2 The test sample bottles are filled with the substance to be transported or a test substitute—water; if water is used, its volume must account for at least 98% of the total volume of the bottle. 6.1.3 For the temperature resistance test, the sample bottles are filled with air or nitrogen up to a pressure of 2.7 MPa. 6.2 Vertical impact drop test 6.2.1 Test equipment: It must meet the requirements specified in GB/T 4857.5-1992. 6.2.2 Drop height: The drop height is 1.2 m. 6.2.3 Test method: a) Drop location for the three specimens in the first group: Incline the specimen bottle so that the upper ridge is at the highest point (for bottles without ridges, use the seam or edge); the gravity line of the center of gravity passes through the lower ridge and is perpendicular to the impact surface, with the specimen hitting the impact surface at this lowest point. If the sample bottle has no bulges, then a circumferential seam or edge impact should be used. b) The impact points for the three samples in the second group: They should strike the impact surface at the weakest areas that were not tested during the drops in the first group, such as the valve protection devices or the welds/seams of the bottle body. c) For the sample bottle after being dropped, check whether there are any leaks at the bottle body, valve connections, pressure relief devices, etc. 6.3 Hydrostatic Testing 6.3.1 Testing Equipment a) Hydraulic pump; b) Pressure gauge; c) Control valve; d) Timer. 6.3.2 Test pressure The test pressure is 1.5 times the working pressure. 6.3.3 Test methods a) The hydraulic testing procedures shall be carried out in accordance with the provisions of 4.6.1 in GB 4351-1997 and 7.2.3 in GB 5100-1994. b) Under hydraulic pressure, it should be no more than per second. A pressure rise rate of 49 MPa, rising slowly to the test pressure. At the test pressure, maintain the pressure for 5 minutes. 6.4 Airtightness test 6.4.1 The airtightness test of the gas cylinder shall be carried out after the hydraulic test is successful. However, if the operating conditions do not permit the presence of residual test fluid, the hydraulic test may be waived in accordance with the design specifications. 3GB 1 9 5 21 . 1 4 -2 0 0 4 6 . 4 . 2 The gas used for the airtightness test should be dry, clean air, nitrogen, or some other inert gas. 6.4.3 Test equipment: a) Air compressor; b) Pressure reducing valve; c) Pressure gauge; d) Timer; e) Water collection container for leak detection. 6.4.4 The test pressure shall be the greater of the working pressure of the medium to be filled and 1.2 MPa. 6.4.5 Test methods a) The test environment temperature shall not be lower than 50°C. b) During the test, the pressure should be increased at a slow rate over a period of no less than 2 minutes to reach the test pressure; thereafter, the entire device is immersed in water and the pressure is maintained for 10 minutes. Finally, a leak check is performed, which can be done by applying soap solution to areas such as the valve seals of the sample container, or using other equivalent leak detection methods. c) Effective protective measures should be taken during the pneumatic testing to ensure the safety of the operators. 6.5 Piling Test 6.5.1 Test Equipment a) It shall meet the requirements of GB/T 4857.3-2000; b) A piling machine or other equivalent equipment shall be used. 6.5.2 Stack height: The stack height is 3 m. 6.5.3 Loading capacity for stacking: P = K × X × r × H / h, where: P represents the loading capacity, in kilograms (kg); K is the degradation coefficient, with a value of 1; H is the stack height (not less than 3 m), in meters (m); h is the height of a single package, in meters (m); M is the gross weight of a single package, in kilograms (kg). 6.5.4 Testing method: Place the sample bottle on the stacking surface, and place a load plate on top of the bottle. The load plate should be positioned at the center of the bottle’s top surface, with its edges being at least 100 mm away from the edges of the bottle’s top surface. Then, place a weight on the load plate. The error between the actual loading amount (including the load plate) and the calculated loading amount should be within ±2%. The distance from the center of gravity of the load to the load plate must not exceed 50% of the bottle’s height. Testing can also be carried out using a stacker. Stacking time: 2 4 b. 6.6 Temperature resistance test: 6.6.1 Test equipment: 6.6.2 a) High-temperature chamber; low-temperature chamber; thermometer; timer. Test method: Place three sample bottles in a high-temperature chamber (60 °C ± 2 °C) and keep them there for 4 hours; a) b) c) d) GB 19521.14-2004 b) Place three sample bottles in a low-temperature chamber (-20 °C ± 20 °C) and keep them there for 4 hours. 6.7 Water pressure rupture test 6.7.1 Test equipment: It shall meet the requirements of 5.5.1 in GB 17268-1998. 6.7.2 Test method: Follow the provisions of 9.2.2 in GB 17268-1998. 7 Marking 7.1 Small and medium-sized pressure vessels shall be marked, in a durable, clear, and legible manner, with the identification mark as well as the marks specific to the gas or pressure vessel, on the shoulder, top, or neck, or on components permanently fixed to the pressure vessel (such as welded collars). 7.2 Except for the “UN” mark, the minimum size of the markings on pressure vessels with a diameter of 140 mm or more shall be 5 mm, while for pressure vessels with a diameter less than 140 mm, the minimum size shall be 2.5 mm. The minimum size of the “UN” mark shall be 10 mm for pressure vessels with a diameter of 140 mm or more, and 5 mm for those with a diameter less than 140 mm. 7.3 The following certification marks shall be used: 7.3.1 The United Nations container mark. This mark may only be applied to pressure vessels that meet the requirements set out in the United Nations Recommendations on the Transport of Dangerous Goods, Model Regulations (13th revised edition) for United Nations-approved pressure vessels. 7.3.2 Technical standards for design, manufacture, and testing. 7.3.3 The approval country code indicated by the identification symbols used for motor vehicles in international traffic; for China, it is C Ne. 7.3.4 The identification mark or stamp of the inspection body registered with the **competent authorities. 7.3.5 Date of the first inspection: year (four digits) and month (two digits), separated by a slash (i.e., “/ ”). 7.4 The following notation shall be used: 7.4.1 The test pressure in pascals shall be preceded by the letters “PH” and followed by the letters “BAR”. 7.4.2 The mass of an empty pressure vessel in kilograms, including all permanently attached components (such as neck rings, foot rings, etc.), shall be followed by the letters “KG”. This mass does not include the mass of valves, valve protective caps or devices, any coatings, or porous materials used for acetylene. The empty weight is expressed with three significant figures, rounded to the last digit. For gas cylinders weighing less than 1 kg, the mass should be expressed with two significant figures, rounded to the nearest digit. 7.4.3 Minimum guaranteed wall thickness of pressure vessels in millimeters, followed by the letter “mm”. Pressure vessels or composite gas cylinders with a water capacity of 1 L or less do not require this marking. 7.4.4 For pressure vessels intended for transporting compressed gases, UN 1001 (acetylene in solution), and UN 3374 (acetylene, solvent-free), the operating pressure in bar shall be preceded by the letter “PW”. 7.4.5 For liquefied gases, the water capacity in liters shall be expressed as three significant figures rounded to the nearest digit, followed by the letter “L”. If the value of the minimum or nominal water capacity is an integer, the digits after the decimal point can be omitted. 7.4.6 For UN 1001 (acetylene in solution), the total mass of the empty pressure vessel, the fittings and attachments that remain in place during loading, porous materials, solvents, and saturated gases shall be expressed with two significant figures, rounded to the nearest digit, followed by the letter “KG”. 7.4.7 For UN 3374 (acetylene, solvent-free), the total mass of the empty pressure vessel, the fittings and attachments that remain in place during loading, and porous materials shall be expressed with two significant figures, rounded to the nearest digit, followed by the letter “KG”. 7.5 The following manufacturing marks shall be used: 7.5.1 Identification symbols for cylinder threads (e.g., 25E); 7.5.2 Manufacturer’s mark registered with the competent authority. When the country of manufacture is different from the country of approval, the country of manufacture symbol, represented by the identification mark used on motor vehicles internationally, shall be placed before the manufacturer’s mark. **The mark and the manufacturer’s mark are separated by a space or a slash; 7.5.3 – Serial number assigned by the manufacturer; 7.5.4 – If it is a steel pressure vessel or a composite pressure vessel with a steel lining that is intended for transporting gases that may make the steel brittle, the letter “H” indicates the compatibility of the steel. CB 1 9 5 21 . 1 4- 2 00 4 7 . 6 The above markers should be listed in three groups as shown in the example below. — The manufacturing marks are the group at the top and should be listed in the order given in 7.5; — the middle group includes the test pressure, and if a working pressure is required, the test pressure should follow immediately after the working pressure; — the certification marks are the group at the bottom and should be listed in the order given in 7.3. 7.7 Other markings may be made outside the side walls, but such markings shall be located in areas of low stress, and their size and depth must not cause harmful stress concentrations. Such markings must not conflict with the prescribed markings. 7.8 In addition to the markings mentioned above, each refillable pressure vessel shall be marked with the date (year and month) of its most recent regular inspection, as well as the registration mark of the inspection body approved by the competent authorities of the country of use. Inspection rules: The manufacturer shall ensure that the small and medium-sized pressure vessels made from hazardous materials comply with the provisions of this standard, and such vessels shall be inspected by the relevant inspection authorities in accordance with this standard. Users of small and medium-sized pressure vessels for hazardous materials have the right to conduct acceptance inspections on the products received in accordance with the provisions of this standard. 8.1 Inspection items: Inspections shall be carried out item by item in accordance with the requirements of Chapters 4, 6, and 7 of this standard. 8.2 Conditions for performance testing: Small and medium-sized pressure vessels among hazardous goods shall undergo performance testing under any of the following circumstances: – When a new product is put into production or an existing product is switched to new production; – After formal production begins, if there are significant changes in the structure, materials, or manufacturing process that may affect the product’s performance; during normal production, once every six months; when production is resumed after a long period of suspension; – When there are significant differences between the results of the factory inspection and those of the previous performance test; – **When a quality supervision agency requests that a performance test be conducted. 8.3 Judgment Rules: In accordance with standard requirements, a general visual inspection is carried out first. The judgment rules follow the normal inspection single-sample sampling plan specified in GB/T 2828-1987, with a qualified quality level of 4.0 (AQL = 4.0). The values for determining qualification are shown in Table 4. Table 3 shows the values for determining qualification, expressed in units of pieces. For normal single-sample sampling with AQL = 4.0: Number of samples – Qualification decision value; Rejection decision value: 2–5, 18–13, 1, 22, 23, 32, 34, 5. On the basis of a successful general visual inspection, performance tests are conducted. If any single sample fails one of the performance tests, that specific test is considered failed; if any one of the performance test items fails, the entire batch of products is deemed unqualified. 8.4 Unqualified batches: If the hydrostatic pressure testing fails, additional samples can be selected arbitrarily from the small and medium-sized pressure vessels in this batch for retesting. If even one of the sample vessels fails the retest, then all the small and medium-sized pressure vessels in this batch should be discarded. After the small and medium-sized pressure vessels that failed other performance tests and were excluded, they are submitted for inspection again under the same strict criteria.