ASME B16.33-2012 pdf download – Manually Operated Metallic Gas Valves forUse in Gas Piping Systems Up to 175 psi(Sizes NPS 1/2 Through NPS 2).
(b) Tensile tests shall be conducted on six dumbbells in accordance with ASTM D412. Three of the tensile tests shall be conducted on dumbbells exposed in n-hexane at 74°F (23°C) for 70 hr in accordance with ASTM D471. The dumbbells shall have a thickness of 0.080 in. + 0.008 in. (2.0 mm ± 0.2 mm). The average of the three individual n-hexane tests shall exceed 60% retention of ultimate elongation and 60% retention of tensile strength at break. The average of the three tests for the non-aged specimen shall be the basis for the percent volume change calculation.
3.2.3.3 Compression Set Tests. Elastomer parts that may be exposed to fuel gas shall he made from materials having a compression set of no more than 25% after 22 hr at 212°F (100°C), in accordance with ASTM D395, Method B, using standard test specimen in accordance with ASTM D395, para. 5.2.
3.2.4 Polytetrafluoroethylene (PTFE) Components.
PTFE materials shall comply with ASTM D4894 or ASTM D4895.
4 DESIGN QUALIFICATION
4.1 General
4.1.1 Each basic valve design shall be qualified and demonstrated as suitable for the service by testing randomly selected production valves of each size, type, and pressure shell material according to the design qualification tests required by this section.
4.1.2 All tests, unless otherwise specified, shall be conducted at a temperature of 74°F ± 15°F (23°C ± 8°C).
4.1.3 Before each test is conducted, the valve shall be in the condition in which it would be placed in service.
4.2 Gas Tightness
4.2.1 The valve shall provide a shutoff when in the closed position and shall not leak to the atmosphere in the open or closed position when subjected progressively to internal air pressure of first 4 psi ± 2 psi (0.3 bar ± 0.1 bar) and then to at least 1.5 times the pressure rating of the valve.
4.2.2 Method of Test for Gas Tightness. With the
valve in the open position and the outlet plugged, the test pressure shall be applied to the inlet of the valve. The valve shall be immersed in a bath containing water at a temperature of 74°F ± 15°F (23°C ± 8°C) for a period of 15 sec. Leakage, as evidenced by flow breaking away) of bubbles shall be cause for rejection. The valve shall then be turned to the closed position, outlet opened and the test repeated.
4.2.3 Other means of leak detection may be used provided they can be shown to be equivalent in leak detection sensitivity.