BS ISO 15364:2016 pdf download – Ships and marine technology — Pressure/vacuum valves for cargo tanks
5.2 Non-metallic materials, other than gaskets, seals and diaphragms as allowed by 6.11, shall not be used in the construction of pressure retaining components of the device. Resilient seals may be installed only if the device is still capable of effectively performing its flame arresting function when the seals are worn down, partially or completely damaged or burned. Non-metallic gaskets shall be made of non- combustible material and suitable for the service intended.
5.3 Materials for connecting pressure-vacuum valves to their respective piping systems should meet standards for physical characteristics similar to those of the piping systems to which they are connected.
5.4 The possibility of galvanic corrosion shall be considered in the selection of materials (see Annex D for additional considerations).
5.5 The verified drawings shall include a complete bill of materials showing conformity with this subclause and any other material requirements listed in Clause 6.
6 Other requirements
6.1 The maximum gas leakage rate shall be provided and expressed as the volume in standard air that may leak from the valve at 75 % of the nominal setting as determined by the manufacturer. See Annex I for suggested leakage rates.
6.2 Housings, elements, and seal gasket materials shall be capable of withstanding the maximum and minimum pressures and temperatures to which the device may be exposed under normal operating conditions.
6.3 Where welded construction is used for pressure retaining components, welded joint design details, welding and non-destructive testing shall be in accordance with National or International Standards. Welding procedures should be in accordance with the ISO 15607 series. Welders should be qualified according to the ISO 9606 series. Non-destructive testing should comply with ISO 5817. Alternative equivalent National/International Standards may be used.
6.4 End-of-line pressure-vacuum valves shall be designed, such that condensed vapour and water in the pressure-retaining zone drain from the device into the tank and do not impair the efficiency of the device. The design shall also prevent the accumulation of water inside the device and subsequent blockage due to freezing. The design shall prevent pockets of water or product from accumulating.
6.5 All fasteners essential to the operation of the device shall be protected against loosening.
6.6 Devices shall be designed and constructed to minimize the effect of fouling under normal operating conditions.
6.7 Devices shall be capable of operating over the full range of ambient air temperatures anticipated. Devices shall be capable of operating in freezing conditions (such as may cause blockage by freezing cargo vapours or by icing in bad weather). Devices shall also be capable of operating at whatever surface temperature is developed by heating arrangements. Where a valve is intended to be fitted in a ship that will be operated in climate conditions that might hamper its operation, e.g. seawater icing, the instruction manual should contain appropriate information to ensure continued operation.
6.8 End-of-line devices are required to direct the efflux vertically upward (see SOLAS 2009, Ch. II-2 Regulation 4, and the minimum average velocity of air through a cross section of the valve’s outlet to atmosphere shall not be less than 30 m/s for all flow rates.
6.9 A manual means (e.g. check-lift) shall be provided to verify that any valve disc and other moving elements lift freely and fully and cannot remain in the open position. The design shall be such that the device is verified not to be inoperable due to corrosion, residue build-up or icing, when the aforementioned manual means is used in combination with the manufacturer’s requirements for visual inspection.
6.10 Valve discs and other moving parts shall be guided by a suitable means to prevent binding and ensure proper self-closing (seating), taking into account the possible build-up of condensed vapours passing through the valve during loading, when maintenance is carried out in accordance with the manufacturer’s requirements. Valve discs and other moving parts shall close against the valve seat by metal to metal contact. Where the valve closes against a metal seat and a resilient seal is added to reduce gas leakage, the valve’s performance in terms of flow shall not be affected if the seal is destroyed, damaged or is otherwise carried away.BS ISO 15364 pdf download.