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1. General Provisions 1.1 Scope of Application This standard applies to the installation and selection of IIA-class petroleum gas pipeline flame arresters in petrochemical process units. 1.2 Relevant standards: GB13347 \"Performance and testing methods for flame arresters in petroleum and gas pipelines\"; GB50058 \"Code for design of electrical installations in explosive and fire-hazardous environments\". 2. Installation and selection of pipeline flame arresters: 2.1 Pipeline flame arresters are safety protection devices, and the performance and testing methods of such flame arresters must comply with the relevant provisions of GB13347 \"Performance and testing methods for flame arresters in petroleum and gas pipelines\". Its classification and performance are given in Appendix A of this standard. 2.2 The flame arrester selected shall ensure that, under operating conditions, the flame propagation speed at the location where the arrester is installed is lower than the arrester’s safe flame arrestation speed ； The explosion pressure within the pipeline shall not exceed the safe range determined through monitoring of the flame arrester selected. 2.3 Generally, the specifications of the flame arrester can be selected based on the diameter of the oil and gas pipeline. 2.4 The flame arrestor layer inside the flame arrester should not be made of metal mesh; instead, a core composed of stainless steel corrugated strips is preferred. 2.5 Pipe flame arresters shall be connected by flanges. 2.6 Fire arrestors used in cold regions shall have housings with heating jackets, either partially or entirely, or other heat tracing measures may be employed. 2.7 When there are no other backflow prevention devices, a pipe flame arrester should be installed in the fuel gas pipeline of the heating furnace. 2.7.1 When the ratio of the pipe length (i.e., the distance from the location where the flame arrester is installed to the point of ignition) to the pipe diameter is less than 20, a flame and explosion arrestive pipe flame arrester should be used, and it is advisable to install it near the source of fire. 2.7.2 When the ratio of pipe length to diameter is greater than 20, an explosion-proof pipe flame arrester should be used, and it should be installed away from sources of fire. Once it is decided to use an explosion-proof pipe flame arrester, determine the minimum installation distance from the source of fire according to Table 1. Table 1 Minimum installation distance for explosion-proof pipe flame arresters. Nominal diameter of pipe DN (mm): 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200. Minimum installation distance L (m): 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0, 8.0, 10.0, 10.0, 10.0, 10.0, 10.0, 2.8. Since combustible gases may be released into the atmosphere through the pipes, it is advisable to install explosion-proof pipe flame arresters near the outlet. 2.9 The housing of the flame arrester shall be made of cast iron, carbon steel welded components, or other metal materials equivalent as required by the user ； The core shell and core member retaining ring of the flame arrester shall be made of stainless steel. Appendix A Classification and Performance of Flame Arresters A1 Flame arresters are used to prevent backfire flames at the pipe ends from spreading in the direction of the gas flowing through the pipe. A2 Based on the range of speeds at which they prevent the spread of flashback flames, flame arrestors are divided into two types: those that prevent deflagration and those that prevent detonation. A2.1 Flame arrestors of the flame inhibition type are installed at pipe ends or in pipes near pipe ends to prevent flames from propagating and spreading at subsonic speeds. Its main performance shall meet the requirements specified in the national standard GB13347 \"Flame arrestor performance and test methods for petroleum gas pipelines\", namely, \"A flame arrestor designed to prevent deflagration must withstand 13 consecutive deflagration tests, and it must prevent subsonic flames from passing through in each test.\" ”A2.2 Deflagration-type flame arresters are installed in pipes located at a distance from the pipe ends, to prevent flames from propagating and spreading at supersonic or sonic speeds. Its main performance shall comply with the provisions of the national standard GB13347 \"Flame arrestor performance and test methods for petroleum gas pipelines\", namely, \"Explosion suppression type flame arrestors must withstand 13 consecutive explosion suppression tests, and in each test they must prevent supersonic flames from passing through.\" ”Appendix B Explanation B1, Clause 2.4: There are currently many types of flame arrester cores. Metal mesh should no longer be used in production due to its low strength and poor explosion resistance; instead, stainless steel corrugated strip flame arrester cores are preferable, as they offer advantages such as good explosion resistance, high strength, corrosion resistance, ease of cleaning, and simple manufacturing.