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Similar standardsGB 27790-2020: City gas pressure regulators---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/GB27790-2020GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 91.140 P 47 Replacing GB 27790-2011 City gas pressure regulator Issued on. NOVEMBER 17, 2020 Implemented on. DECEMBER 01, 2021 Issued by. State Administration for Market Regulation; Standardization Administration of the People's Republic of China. Table of ContentsForeword... 4 1 Scope... 6 2 Normative references... 6 3 Terms and definitions, symbols... 9 4 Classification and models... 19 5 Structure and materials... 21 6 Requirements... 31 7 Test methods... 38 8 Inspection rules... 56 10 Packaging, transportation and storage... 60 Annex A (normative) Physical and mechanical properties and gas resistance of rubber materials... 62 Annex B (informative) Storage of voltage regulator rubber parts... 63 Annex C (informative) Alternative method for determining flow coefficient of large flow regulator... 64 Annex D (informative) Characteristics of volumetric flow rate... 66 Annex E (informative) Noise... 691 ScopeThis Standard specifies the terms and definitions, symbols, classification and marking, structure and materials, requirements, test methods, inspection rules, marking, labeling, instruction manual, packaging, transportation and storage of gas pressure regulators for city gas (hereinafter referred to as pressure regulators). This Standard applies to pressure regulators for regulating outlet pressure with an inlet pressure not exceeding 10.0 MPa, an operating temperature range not exceeding - 20℃~60℃ and a lower limit not lower than the gas dew point temperature, and a nominal size not exceeding 400 mm. This Standard does not apply to pressure regulators for bottled liquefied petroleum gas and dimethyl ether.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 150 (all parts), Pressure vessels GB/T 191, Packaging -- Pictorial marking for handling of goods GB/T 229, Metallic materials -- Charpy pendulum impact test method GB/T 528, Rubber, vulcanized or thermoplastic -- Determination of tensile stress- strain properties GB/T 531.1, Rubber, vulcanized or thermoplastic -- Determination of indentation hardness -- Part 1.Durometer method (Shore hardness) GB/T 699, Quality carbon structure steels GB/T 1047, Pipework components -- Definition and selection of nominal size GB/T 1173, Casting aluminium alloy GB/T 1220, Stainless steel rod GB/T 1239.2, Cold coiled helical springs technical specifications -- Part 2. Compression spring GB/T 1348, Spheroidal graphite iron castings GB/T 1591, High strength low alloy structural steels GB/T 1681, Rubber -- Determination of rebound resilience of vulcanizates GB/T 1682, Rubber, vulcanized -- Determination of low-temperature brittleness (single test piece method)3 Terms and definitions, symbols3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 gas pressure regulator A device that automatically adjusts the gas outlet pressure to stabilize it within a certain pressure range. 3.1.2 series of pressure regulator A general term for voltage regulators of different nominal sizes with similar structures under the same design principle. 3.1.3 direct acting pressure regulator A pressure regulator that uses changes in outlet pressure to directly control the actuator to drive the movement of the regulating element. 3.1.4 indirect acting pressure regulator A pressure regulator that uses changes in outlet pressure, amplified by a controller, to control the driver to drive the regulating element to move. 3.1.5 meter pressure regulator A pressure regulator installed in front of the user's gas meter, with a nominal size not greater than DN25 and a maximum inlet pressure not greater than 0.2 MPa. 3.1.6 integrated monitor When the outlet pressure of the pressure regulator exceeds the setting range of the working pressure regulator, a pressure regulating unit which is connected in series with the working pressure regulator starts to operate to maintain the outlet pressure of the pressure regulator within the allowable range.4 Classification and models4.1 Classification The classification of voltage regulators shall comply with the requirements of Table 2. 4.2 Models 4.2.1 Model compilation The product model compilation shall meet the following requirements. 4.2.2 Examples Examples of voltage regulator models are as follows.5 Structure and materials5.1 General requirements 5.1.1 Design pressure 5.2 Structure 5.2.1 Inlet and outlet connection types 5.2.1.1 The connection between the pressure regulator and the upstream and downstream pipelines shall meet the following requirements. 5.2.1.2 The nominal pressure of the flange shall not be less than the design pressure of the regulator housing and shall be selected from the series of 0.6 MPa, 1.0 MPa, 1.6 MPa, 2.0 MPa, 2.5 MPa, 4.0 MPa, 5.0 MPa, 6.3 MPa, 10.0 MPa and 11.0 MPa. 5.2.1.3 The nominal pressures of the inlet and outlet flanges of the pressure regulator shall be the same. 5.2.2 Other configurations 5.2.2.1 The driving pressure of the indirect acting pressure regulator shall be provided by the inlet gas of the pressure regulator. 5.2.3 Structural requirements for meter pressure regulator 5.2.4 Nominal size and structural length 5.3 Materials 5.3.1 General requirements 5.3.2 Metal materials 5.3.2.1 The metal materials of the voltage regulator parts shall meet the following requirements. 5.3.2.3 The materials of pressure-bearing parts shall meet the following requirements. 5.3.2.4 When the pressure-bearing parts of the voltage regulator are made of carbon steel, high-quality carbon structural steel shall be selected. The chemical composition of carbon steel and low-alloy steel used for welding shall meet the following 5.3.3 Non-metallic materials 5.3.3.1 Diaphragms and other rubber parts shall be made of rubber materials that are resistant to corrosion by the working medium. Diaphragms shall be reinforced with synthetic fibers. 5.3.3.2 The physical and mechanical properties and gas resistance of materials of rubber parts such as diaphragms, valve gaskets, O-rings, etc. shall comply with the requirements of Annex A.6 Requirements6.1 Appearance 6.1.1 The surface of the voltage regulator shall be treated with anti-corrosion. The anti- corrosion layer shall be uniform and have a uniform color without any defects such as peeling, cracking, or bubbles. 6.1.2 The connecting pipes between the pressure regulator and the auxiliary devices and the pilot shall be smooth and free of damage such as dents and bumps. 6.1.3 The surface of the pressure regulator valve body shall be marked with a permanent arrow according to the medium flow direction. 6.2 Strength of pressure-bearing parts 6.2.1 Pressure-bearing parts shall be subjected to strength tests at 1.5 times the design pressure p and not less than p + 0.2 MPa. The test results shall meet the following requirements. 6.2.2 Metal diaphragms shall be subjected to hydraulic pressure tests. The test pressure shall meet the requirements of 6.2.1 and there shall be no leakage or abnormal deformation. 6.3 Inspection of finished diaphragm products 6.4 External seal 6.4.1 The pressure regulator shall be subjected to an external sealing test after passing the hydraulic strength test of the pressure-bearing parts. 6.4.2 The external seal of the pressure regulator shall meet one of the following requirements. 6.5 Performance 6.5.1 General requirements The type inspection of performance shall comply with the requirements of 6.5.2 to 6.5.5. The exit-factory inspection shall comply with the requirements of 6.5.2.1, 6.5.4.1 and 6.5.5.2. 6.5.2 Accuracy level AC 6.6 Flow coefficient Cg 6.6.1 The flow coefficient Cg of the pressure regulator shall not be less than 90% of the value declared by the manufacturer. 6.6.2 For the calculation formula of flow coefficient Cg, please refer to Annex C. 6.7 Adaptability at extreme temperatures 6.7.1 External seal The external seal of the voltage regulator under extreme temperature shall comply with the requirements of 6.4. 6.7.2 Lock-up pressure pb When the pressure regulator is at the limit temperature, the inlet pressure is at the maximum and minimum values respectively, and the set point p2s is at the minimum value, the lock-up pressure shall meet the following requirements. 6.7.3 Opening and closing flexibility Under extreme temperatures, the voltage regulator shall be opened and closed flexibly within the full stroke range. 6.8 Durability After the regulator has been opened and closed for 30,000 times at room temperature with a stroke greater than 50% of the full stroke (excluding the closed and fully open positions), the external seal of the regulator shall meet the requirements of 6.4.The accuracy shall meet the requirements of 6.5.2.The lock-up performance shall meet the requirements of 6.5.4. 6.9 Failure state The control member of a fail-open regulator shall tend to open or open. The control member of a fail-closed regulator shall tend to close or close under any of the following conditions.7 Test methods7.1 General requirements 7.1.1 Laboratory temperature and test pressure 7.1.2 Test medium 7.1.3 Test equipment 7.1.3.1 The principle of the test system for the performance type test and the flow coefficient test is shown in Figure 4a) ~ 4d), and shall meet the following requirements. 7.1.3.2 The system principle of the test bench for exit-factory inspection of performance is shown in any system principle diagram of Figure 4a)~4d). The length of the downstream pipeline of the pressure regulator shall not be greater than the minimum value specified in Figure 4.There shall be no additional volume downstream. 7.1.4 Measurement accuracy 7.2 Appearance Check by visual inspection whether it complies with the requirements of 6.1. 7.3 Strength of pressure-bearing parts 7.4 Inspection of finished diaphragm products 7.4.1 Diaphragm pressure resistance test The diaphragm shall be tested in combination with the diaphragm disc (or corresponding fixture) in the test fixture. The test fixture shall place the diaphragm in the position with the maximum effective area. The movement of the diaphragm exposed from the diaphragm disc (or corresponding fixture) and the fixture shall not be restricted by the test fixture. During the test, the pressure shall be slowly increased to the test pressure on the high-pressure side of the diaphragm. The pressure holding time shall not be less than 10 min. Check whether the test results meet the requirements of 6.3.1. 7.5 External seal 7.5.1 After the pressure regulator has passed the hydraulic strength test of the pressure- bearing parts, an external seal test shall be carried out. During the external seal test, the pressure regulator and its additional devices shall be assembled as a whole. 7.5.2 The test pressure on the inlet side of the meter pressure regulator shall be 1.1 times the maximum inlet pressure and shall not be less than 0.02 MPa. The test pressure on the outlet side shall be 1.1 times the lock-up pressure and shall not be less than 0.02 MPa. 7.6 Performance 7.6.1 Type inspection of performance 7.7 Flow coefficient Cg 7.8 Adaptability at extreme temperatures 7.8.1 At the extreme temperature, carry out the external sealing test according to the method shown in 7.5 and check whether the test results meet the requirements of 6.7.1. 7.9 Durability After the regulator is operated at room temperature for 30,000 times with a stroke greater than 50% of the full stroke (excluding the closed and fully open positions) and a frequency greater than 5 times/min, the following tests are carried out in sequence to check whether it meets the requirements of 6.8. 7.11 Integrated shut-off device 7.11.2 Shut-off pressure accuracy class 7.11.3 Response time According to the test method specified in 6.2.7 of CJ/T 335-2010, test the response time of the integrated shut-off device of the voltage regulator. Check whether the test results meet the requirements of 6.10.3. 7.12 Integrated monitor8 Inspection rules8.1 Inspection categories Inspections are divided into exit-factory inspection and type inspection. 8.2 Inspection items See Table 17 for inspection items. 8.3 Exit-factory Inspection 8.3.1 Each product shall be subject to exit-factory inspection before leaving the factory. A product quality certificate shall be issued if the inspection is qualified. 8.3.2 The exit-factory inspection items shall comply with the requirements of Table 17. 8.4 Type inspection 8.4.1 Type inspection shall be carried out in any of the following situations. 8.4.2 Type inspection items shall comply with the requirements of Table 17. 8.5 Judgment rules 8.5.1 Exit-factory inspection All items of factory inspection must be qualified before leaving the factory. Unqualified items are allowed to be reworked and re-inspected. If they are still unqualified, the voltage regulator shall be judged as unqualified and shall not be shipped. 8.5.2 Type inspection When all indicators in the type inspection meet the requirements, the type inspection shall be judged to be qualified. 9.Marks, labels, instructions for use 9.1 Marks and labels 9.1.1 Voltage regulator 9.1.1.1 A nameplate shall be placed in a conspicuous position on the voltage regulator. The nameplate shall comply with the requirements of GB/T 13306 and shall at least include the following information. 9.1.1.2 The direction of gas flow shall be permanently marked on the valve body with an arrow. 9.1.2 Packaging box The packaging box shall have packaging storage and transportation pictorial marks and transport packaging delivery and receipt marks, which shall comply with the requirements of GB/T 191 and GB/T 6388. 9.2 Instructions for use The preparation of the instruction manual shall comply with the requirements of GB/T 9969 and shall include the following contents. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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