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GB/T 34531-2017: Periodic inspection and evaluation of liquefied dimethyl ether steel cylinders Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid
Similar standardsGB/T 34531-2017: Periodic inspection and evaluation of liquefied dimethyl ether steel cylinders---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT34531-2017GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 23.020.30 J 74 Periodic inspection and evaluation of liquefied dimethyl ether steel cylinders Issued on: OCTOBER 14, 2017 Implemented on: MAY 01, 2018 Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of Chin; Standardization Administration of the People's Republic of China. Table of ContentsForeword... 3 1 Scope... 4 2 Normative references... 4 3 Inspection items... 5 4 Inspection preparation... 5 5 Appearance inspection and evaluation... 6 6 Inspection and evaluation of valve seats... 8 7 Wall thickness measurement... 9 8 Volume measurement... 9 9 Water pressure test... 10 10 Cylinder valve inspection and assembly... 10 11 Air tightness test... 11 12 Others... 12 Annex A (normative) Depth measurement methods for dents, pits, bumps and scratches ... 14 Annex B (normative) Method for measuring the volume of water in steel cylinders. 16 Annex C (informative) Inspection mark ring... 17 Bibliography... 18 Periodic inspection and evaluation of liquefied dimethyl ether steel cylinders1 ScopeThis Standard specifies the basic methods and technical requirements for the periodic inspection and evaluation of liquefied dimethyl ether steel cylinders (hereinafter referred to as "steel cylinders") designed and manufactured in accordance with GB/T 33147. This Standard applies to steel cylinders that are used at normal ambient temperatures of -40°C~60°C, with a nominal working pressure of 1.6 MPa, a nominal volume not greater than 150 L, and can be repeatedly filled with liquefied dimethyl ether (in accordance with the provisions of GB/T 25035).2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 3864, Industrial Nitrogen GB/T 7144, Coloured cylinder mark for gases GB/T 8335, Special threads for gas cylinders GB/T 8336, Special thread gauges for gas cylinders GB/T 9251, Methods for hydrostatic test of gas cylinders GB/T 10878, Special taps of taper threads for gas cylinders GB/T 12137, Methods for leakage test of gas cylinders GB/T 33146, Valves for liquefied dimethyl ether cylinders GB/T 33147, Liquefied dimethyl ether cylinders NB/T 47013.2, Nondestructive testing of pressure equipment -- Part 2.Radiographic testing NB/T 47013.4, Nondestructive testing of pressure equipment -- Part 4.Magnetic particle testing NB/T 47013.5, Nondestructive Testing of Pressure Equipment -- Part 5.Penetrant Testing TSG R0006-2014, Supervision regulation on safety technology for gas cylinder3 Inspection itemsThe regular inspection items of steel cylinders include. appearance inspection, valve seat inspection, wall thickness measurement, cylinder valve inspection, water pressure test, and air tightness test. After the appearance inspection, if there is any doubt about the volume of the steel cylinder, the volume shall be measured.4 Inspection preparation4.1 Records 4.1.1 Check and record the manufacturing mark and inspection mark of each cylinder. The record shall at least include the manufacturer code or manufacturing license number, cylinder number, manufacturing year and month, filling medium, nominal working pressure, water pressure test pressure, cylinder weight, nominal volume, cylinder design wall thickness, design service life, last inspection date (year, month) and inspection agency code. 4.1.2 For steel cylinders produced by manufacturers that have not obtained a special equipment manufacturing license, steel cylinders with unclear manufacturing marks or incomplete items and no traceable evidence, and steel cylinders that are prohibited from being used according to regulations of the special equipment safety supervision and management department, they will not be inspected after recording and will be treated as scrapped. 4.1.3 Cylinders that exceed their designed service life from the date of manufacture indicated by the steel stamp shall be recorded and not inspected and shall be treated as scrapped. 4.1.4 For cylinders that are determined to be unusable and cylinders whose steel stamp marking media do not match, they will be recorded and not inspected and will be scrapped. 4.2 Treatment of residual gas in the cylinder 4.2.1 Before inspecting the cylinders, appropriate methods shall be used to recover the residual gas in each cylinder, under the premise of ensuring no leakage, no pollution to the environment, and no impact on the health of operators. For cylinders whose valves cannot be opened and cannot be proved to have residual pressure, they shall be stored separately from the cylinders to be inspected. They shall be marked for proper disposal. The residual gas in the cylinders that are scrapped after appearance inspection shall also be recovered one by one. 4.2.2 The residual gas in the cylinder shall be handled internally in a way that does not damage the cylinder material or reduce the performance of the cylinder material. 4.2.3 After the cylinders are recovered and treated, the residual gas concentration is measured with a combustible gas detection instrument. For cylinders with a concentration higher than 0.4% (volume fraction), the residual gas in the cylinders shall be re-processed. 4.3 Disassembly of cylinder valve and cleaning of cylinder surface 4.3.1 When the pressure inside the cylinder is confirmed to be consistent with the atmospheric pressure, remove the cylinder valve using an instrument that does not damage the metal of the cylinder. 4.3.2 Gas cylinders whose valves cannot be opened shall be stored separately from the cylinders to be inspected for proper handling. 4.3.3 Use a surface treatment device that does not damage the cylinder body. Remove rust and coatings from the outer surface of each cylinder one by one.5 Appearance inspection and evaluation5.1 Initial inspection and evaluation of appearance Inspect and evaluate the appearance defects of each cylinder. Cylinders that fall into any of the following conditions shall be scrapped. a) Cylinders with shrouds detached or their welded joints broken, and with cracks on the butt joints of the cylinder body; b) Cylinders whose bases have fallen off, are severely deformed, corroded, cracked, or have other defects that affect their uprightness and stability; c) Cylinders that have been welded, repaired, patched, disassembled and refurbished. 5.2 Appearance review and evaluation 5.2.1 Visual inspection Conduct visual inspection on the outer surface of each cylinder. Check whether there are cracks, bulges, wrinkles, interlayers, pits, dents, scratches, depressions, corrosion and other defects on the surface. For the parts with pits, dents, scratches and corrosion defects found in the appearance inspection, the minimum wall thickness of the cylinder 5.2.6.2 Steel cylinders with cracks on the weld surface and heat-affected zone shall be scrapped. 5.2.6.3 Steel cylinders with dents or irregular changes on the weld surface shall be scrapped. 5.2.6.4 If there are scratches, dents or pits on the longitudinal and circumferential welds and heat-affected zones, after grinding, the steel cylinders with welds lower than the parent material shall be scrapped. The steel cylinders with the remaining wall thickness of the heat-affected zone less than the designed wall thickness shall be scrapped. 5.2.6.5 Steel cylinders with a depression depth of 6 mm or more in the heat-affected zone of the longitudinal or circumferential weld shall be scrapped. 5.2.6.6 When there is doubt about the type and severity of surface defects of welded joints or the inspector deems it necessary, the inspector shall determine the location, method and proportion of non-destructive testing and conduct magnetic particle testing according to NB/T 47013.4, penetration testing according to NB/T 47013.5 or radiographic testing according to NB/T 47013.2.The results of non-destructive testing shall be evaluated according to NB/T 47013.4, NB/T 47013.5 and NB/T 47013.2.The qualified level of magnetic particle and penetration testing shall not be lower than Level I. The technical level of X-ray testing shall not be lower than Level AB. The qualified level of weld quality shall not be lower than Level III. 5.3 Internal inspection and evaluation 5.3.1 Internal inspection of cylinders shall be carried out using instruments or devices that can clearly observe the inside of the cylinder. 5.3.2 If there is corrosion inside the cylinder, it shall be assessed in accordance with 5.2.3. 5.3.3 For cylinders with thermal damage inside, evaluation shall be carried out in accordance with 5.2.4. 5.3.4 If there is any doubt about the type and severity of defects in welded joints and heat-affected zones inside the cylinder, an evaluation shall be conducted in accordance with the requirements for X-ray testing in 5.2.6.6.6 Inspection and evaluation of valve seats6.1 Inspection content and evaluation methods 6.1.1 Check the valve seats and threads visually or with a low-power magnifying glass for cracks, deformation, corrosion or other mechanical damage. 6.1.2 Cylinders with cracked, tilted or collapsed valve seats shall be scrapped. 6.1.3 The threads shall not have cracks or crack defects. However, slight damage that does not affect the use is allowed. That is, no more than 3 teeth are allowed in the effective thread, the length of the gap shall not exceed 1/6 of the circumference, and the depth of the gap shall not exceed 1/3 of the tooth height. 6.2 Thread repair Threads with slight corrosion, wear or other damage shall be repaired with left-handed taps in accordance with GB/T 10878.After repair, they shall be inspected with a gauge in accordance with GB/T 8336.The inspection results shall meet the requirements of GB/T 8335 for left-handed thread structure. Steel cylinders that still fail to meet the inspection requirements after thread repair shall be scrapped.7 Wall thickness measurement7.1 Measurement requirements 7.1.1 In addition to local thickness measurement of defective parts of steel cylinders, fixed-point thickness measurement shall also be carried out on each cylinder. 7.1.2 The thickness measurement point shall be selected at one point in the transition zone between the upper and lower heads. For the cylinder, one point shall be selected at 50 mm from both sides of the circumferential weld or one side (for three-section cylinders). For cylinders with severe corrosion, the corrosion area shall be measured to find the point with the minimum value of the remaining wall thickness. For three- section cylinders, two additional points shall be measured in the lower part of the cylinder and the transition zone between the lower head. 7.2 Results evaluation Steel cylinders with remaining wall thickness less than the designed wall thickness shall be scrapped.8 Volume measurement8.1 General If there is any doubt about the volume of the cylinder after visual inspection, the volume shall be measured. 8.2 Requirements for weighing instruments The weighing scale shall be accurate. The maximum range of the scale shall be 1.5~3.0 10.2 Cylinder valve assembly 10.2.1 The sealing materials of the cylinder valve and valve seat shall comply with the relevant provisions of GB/T 33146. 10.2.2 For steel cylinders with liquid phase tubes, the cylinder valve and liquid phase tube shall be firmly assembled. 10.2.3 The cylinder valve shall be assembled firmly. Ensure the effective number of threads and sealing performance of the connection with the valve seat. After assembly, the number of exposed threads is generally 1~3.11 Air tightness test11.1 Test requirements 11.1.1 After the cylinders have passed the water pressure test, they shall be tested for air tightness. 11.1.2 For cylinders that are tested for air tightness using air as the medium, the concentration of the gas released by the residue in the cylinder shall be measured before the test. For cylinders with a concentration greater than 0.4% (volume fraction), the residual gas shall be re-processed. Only after the concentration meets the requirements can the test be carried out using air as the medium, otherwise the test shall be carried out using nitrogen. 11.1.3 The compressed air used in the air tightness test shall not contain oil or water. If nitrogen is used, its purity shall not be lower than the Class II secondary index specified in GB/T 3864. 11.1.4 The airtightness test method of steel cylinders shall be the immersion method. The gas filling device, test water tank, test conditions and methods shall comply with the provisions of GB/T 12137. 11.1.5 If the inflation device leaks during the inflation process or the cylinder valve is improperly assembled and leaks during the test, the test shall be stopped immediately and the test shall be resumed after repair or reassembly. 11.1.6 The air tightness test pressure is 1.6 MPa. The pressure holding time shall not be less than 1 min. 11.2 Results evaluation During the air tightness test, steel cylinders with leakage shall be scrapped.12 Others12.1 Inspection marks 12.1.1 Steel cylinders that have passed the inspection shall have a permanent, traceable, and legible inspection mark on them, which shall include the inspection agency code, the current and next inspection dates (year, month). 12.1.2 The position and method of the cylinder inspection mark shall comply with the relevant requirements of Annex B of TSG R0006-2014.Inspection institutions with rolling devices or special machinery can roll or print the inspection mark on the appropriate position of the cylinder shield. For inspection institutions that use the inspection mark ring (refer to Annex C for the external dimensions) on the conical tail of the cylinder valve, the inspection mark shall be printed on the specified position of the inspection mark ring by special machinery or manual methods. 12.1.3 After the cylinder is re-coated, a safety warning shall be affixed to the inner wall of the cylinder shield. The content shall comply with the provisions of GB/T 33147. 12.2 Coating 12.2.1 After the qualified steel cylinders are cleaned of dust, oil, rust, scale and welding spatter left over from manufacturing, they are coated in a dry state. 12.2.2 In addition to the provisions of GB/T 7144, coating shall also be carried out in accordance with the following provisions. a) The surface of the cylinder is painted light green. The color card number is RAL6017-RAL6018.The words "liquefied dimethyl ether" are painted in the middle of the cylinder surface. Its height is 60 mm~80 mm; b) The "next inspection date" is printed in a suitable size on the lower middle part of the cylinder surface; c) For cylinders with liquid phase tubes, the word "liquid phase" of moderate size shall be painted on the front of the upper head. The font shall be Changfangsong font and the color shall be red; d) The coating shall be uniform. No defects such as bubbles, flow marks, cracks or peeling shall be present; e) When applying the cylinder paint color, the inspection color standard shall be sprayed on the inspection mark. When using the inspection ring, it shall be sprayed on the shield. 12.3 Inspection records and reports ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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