ANSI IAS PRD 1A-1999 pdf download BASIC REQUIREMENTS FOR PRESSURE RELIEF DEVICES FOR NATURAL GAS VEHICLES (NGV) FUEL CONTAINERS
6. GENERALREQUIREMENTS
6.1 Materiai Requirements. Pressure relief device housings shall be fabricated from stainless steel, brass or aluminum. The alloy, heat treatment, and manufacturing method should be chosen such that the housings are resistant to stress corrosion cracking in a Natural Gas Vehicle service environment. Other components may be made of any suitable material. The materials shall be such that there will be no significant change in the functioning of the device, and no harmful corrosion or deterioration of the materials when subject to the service conditions given in Sedion 4.
7. DESIGN QUALIFICATION TESTING
7.4 Pressure Cycling. Five units of the pressure relief device assembly shall be cycled 20,000 times between not more than 10 percent of the service pressure and not less than 125 percent of the service pressure. The first 2,000 cydes shall be conduded at a temperature of +82″C (+lSO”F). The remaining 18,ûûû cycles shall be conducted at a temperature of 57°C (+135″F). The maximum pressure cycling rate is 10 cycles per minute. Following this test, the pressure relief device assembly shall meet the requirements of Section 7.11 (Leakage) and Section 7.12 (Benchtop Activation).
Salt Corrosion Resistance. Two units of the pressure relief device assembly shall be tested. Any non-permanent outlet caps shall be removed. Each pressure relief device assembly shall be installed in accordance with the manufacturer’s recommended procedure and pressurized to 125 percent of the service pressure and exposed for 144 hours to a salt spray (fog) test as specified in ASTM BI17 [II], ”Salt Spray (Fog) Testing”, except that in the test of one unit, the pH of the salt solution shall be adjusted to 4.0 le O 2 by the addition of sulfuric acid and nitric acid in a 2 1 ratio,and in the test of the other unit, the pH of the salt solution shall be adjusted to 10.0 f 0.2 by the addition of sodium hydroxide. Additionally, both sait sdutions shall be aerated to provide oxygen and carbon dioxide. Following these tests, each pressure relief device assembly shall meet the reqUirements of Section 7.11 (Leakage) and W o n 7.12 (Benchtop Activation).