Pressure Piping Code-Industrial Piping. Part 6: Safeguarding

Transcription

1 ICS J74 National Standard of the People's Republic of China GB/T Pressure Piping Code-Industrial Piping Part 6: Safeguarding ffi1jtfil~ju1t1 I~tfil ~6$?t: ~~~1? Issued on: December 30, 2006 Implemented on: June 1, 2007 Issued by General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Standardization Administration of the People's Republic of China

2 Contents 1 Scope Normative References Terms and Definitions Safety Relief Devices Flame Arrester Safeguarding... 9 Appendix A (Normative Appendix) Calculation of Safety Relief Device... 12

3 Pressure Piping Code-Industrial Piping-Part 6: Safeguarding 1 Scope This Part sets out the basic requirements of the security protection devices for pressure pipelines within the scope of GB/T (safety relief devices, flame arrester) and security protection. Additional security requirements this Part does not provide should be consistent with other parts of this standard, as well as other existing relevant standards and norms of the country. 2 Normative References The terms of the following documents become a reference to the provisions of this Part by the reference of this part of GB/T With respect to any reference with note of date, all subsequent amendment sheets (not including the contents of the corrigenda) or revised versions shall not apply to this Part, however, it is encouraged for the parties coming to an agreement under this Part, to consider whether to use the latest version of these documents. For undated reference documents, the latest versions thereof apply to this section. GB 150 Steel pressure vessel GB Rupture disc and rupture disk device GB Electrical apparatus for explosive atmospheres-classification of gases or vapors with air according to their maximum experimental safe gaps and minimum igniting currents (eqv IEC :1978) GB/T 3840 GB 5908 Technical methods for making local emission standards of air pollutants Oil Tank flame arrester GB General guideline for preventing electrostatic accidents GB/T GB/T GB/T Valves-General requirements (ISO :1991, MOD) Performance test standard of pressure release device Spring loaded safety valves GB The quenching ability of flame arrester and its test method for petroleum gas piping systems GB/T Pressure piping code-industrial piping-part 1: General Provisions GB/T calculation Pressure piping code-industrial piping-part 3: Design and GB Code of Design on Building Fire Protection and Prevention GB Fire prevention code of petrochemical enterprise design

4 GB Code for design of general plan of industrial enterprises HG/T Settings and selection of safety valve SHIT Specification for selection, inspection and acceptance of pipeline flame arresters for petroleum gas in petrochemical industry SY/T Guide for pressure-relieving and depressurizing systems SY!T Recommended practices to determine the size, selection and installation of the relief device in refinery pressure 3 Terms and Definitions 3.1 Safety relief device In case of non-fire or fire accident, the safety relief device is opened by input static pressure to discharge fluid in order to prevent the internal pressure of system from exceeding a predetermined safe value. Safety relief devices include safety valves and bursting disc devices. 3.2 Safety valve Valve effected by a spring or controlled by pilot valve. When the static pressure exceeds a set pressure at the entrance, the valve clack flaps up and fluid is discharged in order to prevent the system pressure from exceeding a predetermined safety value, and when the pressure dropped back to re-seating pressure, safety relief device can automatically shut down. 3.3 Rupture disk device A safety relief device consists of the rupture disc and clamping device which is unable to re-close, when the pressure difference on either side of bursting disc come to the target value under set temperature, the bursting disc ruptures or losses. 3.4 Set pressure of the safety valve The static pressure when the clack of safety valve begins to rise under running conditions, also known as the opening pressure, or set pressure. With this pressure, measurable opening height occurs and the fluid was in a continuous discharge status, which may be seen or heard. 3.5 Maximum marked burst pressure Blasting test is carried out to the same batch of qualified rupture disc under a certain temperature; the maximum burst pressure attained in the test is the maximum marked burst pressure for this batch rupture disc. 3.6 Maximum relieving pressure In the discharge state, the maximum inlet pressure of the safety valve clack is opened up to the required height. For the rupture disk devices, maximum relieving pressure means maximum pressure the pressure systems can withstand when the rupture disc is broken. 2

5 3.7 Required relief capacity The discharge flow must be relieved from the safety relief system in order to prevent the system from overpressure. 3.8 Relief area The net flow area when the safety valve begins to relieve or the rupture disc bursts. 3.9 Block valve; stop valve Valve used to block or connect fluid in the pipe. Common used block valve include gate valve, ball valves, plug valves, butterfly valves, diaphragm valves and the block valve of plane valve with large valve hole while small flow resistance seat Independent pressurize system The pressure system with one or more devices (containers) connected by pipes and without stop by valves in the middle, the two ends of which have valves to block it from other system Flame arrester pipe. The safety protective equipment used to prevent the spread and extend of flame in the 3.12 Venting flume arrester Installed in the venting pipe of tank to prevent the transmission of an external fire into the tank, divided into tube-end type and ordinary type. Tube-end type venting flume arrester is deflagration resistance type, one end of which connects with the atmosphere, and the top of which is installed with rain-hat, to prevent dust and rain water from entering into the inner side of arrester. Common type venting flume arrester is divided into deflagration resistance type and detonation resistance type, both ends of which connect with the pipes, and connect to the atmosphere through the downstream piping Pipeline flame arrester Installed in the closed piping system, prevent the spread of the flames at one end to another end, divided into deflagration resistance and detonation resistance type Maximum experimental safe gap (MESG) Under standard experiment conditions (O.lMPa, 20 C), the minimum gap width that the flame can not pass through (the gap is 25mm long). 4 Safety Relief Devices 4.1 General provisions Installation of safety relief devices should be able to prevent the over pressure 3