Detail of GB/T 19699-2023

Introduction of GB/T 19699-2023

GB/T 19699-2023 Ships and marine technology - Pressure-vacuum valves for cargo tanks and devices to prevent the passage of flame into cargo tanks 1 Scope This document is applicable to pressure-vacuum valves and to devices to prevent the passage of flame, both protecting cargo tanks, that can be subject to explosive gas/vapour and/or to gas/vapour pressure or vacuum beyond the design parameters of the system/tank. It specifies the minimum requirements for performance and testing. It also specifies design and in-service performance criteria, operational testing and maintenance requirements. Design or manufacturing in accordance with this document does not imply suitability for any given installation, it indicates that certain minimum requirements have been considered and that information necessary for determination of suitability is provided to the buyer of the equipment. This document applies to pressure vacuum valves and flame arresters, both of which can protect cargo tanks from the effects of explosive gases/vapors and/or gas/vapor pressures or vacuums exceeding the system/tank design parameters. The flame test procedures of ISO 16852:2016 are incorporated in this document. Note: Minimum requirements for devices to prevent the passage of flame are found in the International Maritime Organization (IMO) “International Convention for the Safety of Life at Sea, as amended” (SOLAS), Chapter II-2, Regulation 4, and IMO Maritime Safety Committee (MSC) Circular No. 677 (MSC/Circ. 677), “Revised Standards for the Design, Testing and Locating of Devices to Prevent the Passage of Flame into Cargo Tanks in Tankers”, as amended. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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. ISO 5817 Welding - Fusion-weldedjointsinsteel, nickel, titaniumandtheiralloys (beam weldingexcluded) - Quality levels for imperfections ISO 9606 (all parts) Qualification testing of welders ISO 15607 Specification and qualification of welding procedures for metallic materials - Generalrules ISO 16852:2016 Flame arresters - Performance requirements, test methods and limits for use ISO/IEC 17025:2017 General requirements for the competence of testing and calibration laboratories 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 flame arrester device fitted to the opening of an enclosure, or to the connecting pipe work of a system of enclosures, and whose intended function is to allow flow but to prevent the transmission of flame 3.2 dual nozzle valve pressure relief valve that features two high velocity vents with different opening settings integrated into one valve, the flow characteristics of which can be of one or more of the designs full opening valve (3.3), modulating valve (3.7) or transition point valve (3.11) 3.3 full opening valve design that opens fully at maximum 2 % above the set pressure 3.4 high velocity vent valve pressure relief valve designed always to have efflux velocities that prevent the flame propagation against the flow direction 3.5 maximum experimental safe gap; MESG maximum gap of a joint of 25 mm in width which prevents any transmission of an explosion during tests Note: ISO/IEC 80079-20-1 specifies the test apparatus and the test method. 3.6 maximum intended pressure drop largest pressure drop generated over a device for which the test laboratory verifies the corresponding flow capacity 3.7 modulating valve design that opens proportionally with rise in pressure 3.8 pressure-vacuum valve device to relieve the pressure or vacuum formed inside the cargo tanks by opening the valves at the designated setting value to protect the tank from over-pressure or vacuum exceeding the design parameters of the tanks 3.9 standard conditions dry air at 288.15 K (15.00 °C; 59.00 °F) and 101.325 kPa 3.10 third party inspection body organization independent from the manufacturer and user, that is qualified to perform or witness the tests and inspections 3.11 transition point valve design where the valve characteristics change from modulating to full opening at a particular pressure 3.12 verified drawing drawing certified to be authentic and complete by the third party inspection body (3.10) issuing the test report 3.13 verified flow chart pressure versus flow volume presented in a chart certified by the third party inspection body (3.10) issuing the test report 4 Symbols The following symbols are applicable to this document. D pipe inner diameter at device connection Dmin minimum inner diameter of the piping between the device and the tank allowed for non-os-cillating performance Lmax maximum length of the piping between the device and the tank allowed for non-oscillating performance L1 pipe length between the test tank and the device for flow testing L2 pipe length between the test tank and the device during non-oscillation testing Pclosing value of inlet pressure at which the valve disk re-establishes contact with the seat or at which lift becomes zero, when the valve is closing and pressure is decreasing Pclosing1 value of inlet pressure at which the valve disk re-establishes contact with the seat or at which lift becomes zero, when the main valve is closing and pressure is decreasing Pclosing2 value of inlet pressure at which the valve disk re-establishes contact with the seat or at which lift becomes zero, when the extra valve is closing and pressure is decreasing Pmax maximum pressure corresponding to the maximum flow volume (Q3 ) Pset gauge pressure at the device inlet at which the valve is designed to start opening Pset1 gauge pressure at the device inlet at which the main valve is designed to start opening Pset2 gauge pressure at the device inlet at which the extra valve is designed to start opening P1-tpv pressure at which a transition point valve changes from modulating to full opening Q1-fov flow volume needed to open a full opening valve Q1 flow volume needed to open the second nozzle Q2 flow volume needed for a valve to remain fully open Q2-fov flow volume needed to maintain a full opening valve fully open at P set Q1-mv flow volume needed to open a modulating valve Q2-mv flow volume needed to maintain a modulating valve fully open Q1-tpv flow volume at which a transition point valve changes from modulating to full opening Q2-tpv flow volume needed to maintain a transition point valve fully open at P1-tpv Q3 flow volume corresponding to the maximum intended pressure drop over the device Qclose minimum flow required to keep the valve partially open with no contact between the disc and the seat Q2total flow volume needed to maintain the main and extra valves fully open at Pset1 Q3total flow volume corresponding to the maximum intended pressure drop over the dual nozzle valve Vmin minimum volume of the tank allowed for non-oscillating performance

Contents of GB/T 19699-2023