National Standard "General Requirements for Safety Valves"

The General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China (AQSIQ) and the National Standardization Administration have recently issued a revised version of GB/T12241-2005 "General Requirements for Safety Valves".

This standard was drafted by Shanghai Kate Valve Manufacturing Co., Ltd. and Hefei General Machinery Research Institute instead of GB/T12241-2005.

This standard stipulates the terms and definitions of safety valve, design, production test, type test, determination of safety valve performance, determination of the size of safety valve, marking and general requirements such as seal; applicable to the diameter of flow channel not less than 6mm, setting pressure The safety valve is not less than 0.1MPa (1bar) gauge pressure; the design medium and applicable temperature of the safety valve are not limited.

This standard corresponds to ISO 4126-1:2004 "Safety Devices for Overpressure Protection - Part 1: Safety Valves" (English version) and is not equivalent to ISO 4126-1:2004.

The main difference from ISO4126-1 is that the normative references in this standard refer to the corresponding Chinese standards;

- deleted the terminology and definition of "3.1.1.4 pilot-operated safety valve" in ISO 4126-1:2004;

- Removed the provisions for other types of safety devices in "7.1.2 Application Notes" in ISO 4126-1:2004;

——In the scope of Chapter 1 of ISO 4126-1:2004, “applies to relief valves suitable for setting pressures of 0.1 bar gauge or more and to safety valves suitable for setting gauge pressures of not less than 0.1 MPa (1 bar);

- apply the corresponding content or corresponding data of ISO 4126-7:2004 "public data" in ISO 4126-1:2004 to this standard or as an informative appendix to this standard;

- Added informative data in Appendix B "Steam";

- Added informative information in Appendix C "corresponding to the C-value of the isentropic index K";

- Added informational appendix D "Displacement Correction Factor (Kb) for Back Pressure";

—— Added Appendix E “Evaluation of Compression Coefficient Z”;

- Added informative Appendix F "The coefficient of displacement correction Kv for viscosity";

- Added informative Appendix G "Gas properties".

The main changes from this standard compared with GB/T12241-2005 are as follows:

- The name of the standard, "General Requirements for Safety Valves" was changed to "Safety Valves";

——The scope of application of the standard applies to the variation of the diameter of the flow channel not less than 8mm to the diameter of the flow channel not less than 6mm;

- Canceled the requirements on the manufacturer's quality assurance system;

- cancelled the requirements regarding the installation of the safety valve and the adjustment, maintenance and repair;

- canceled Table 2 "overheat correction coefficient Ksh";

- Cancellation of Appendix A, "Derivation of the Thermal Correction Coefficient Ksh," Appendix B, "Derivation of the Compression Coefficient Z," Appendix C, "Typical Overview of Elements Included in the Quality Assurance System," and Appendix D, "Liquid Viscosity Correction Factors." And Appendix E, "Alternative Methods for Theoretical Displacement Calculation" and other five informative annexes;

- Added informational appendix A "Calculation example for determining the size of safety valve for different media";

- Added informative data in Appendix B "Steam";

- Added informative information in Appendix C "corresponding to the C-value of the isentropic index K";

- Added informational appendix D "Displacement Correction Factor (Kb) for Back Pressure";

—— Added Appendix E “Evaluation of Compression Coefficient Z”;

- Added informative Appendix F "The coefficient of displacement correction Kv for viscosity";

- Added informative Appendix G "Gas properties".