ASME B16.38 pdf download

ASME B16.38 pdf download Large Metallic Valves for Gas Distribution Manually Operated, NPS 2 1 / 2 (DN 65) to NPS 12 (DN 300), 125 psig (8.6 bar) Maximum
2.7 Gas Resistance All materials, including lubricants and sealants, shall be resistant to deterioration when exposed to fuel gases such as listed in para. 1.2.
2.8 Temperature Resistance The materials used for valve bodies, plugs, bonnets, unions, and other pressure-containing parts, excluding handles, shall have a solidus temperature in excess of 600°F (427°C).
2.9 Elastomer Components
2.9.1 Air Aging Tests. Elastomer parts that are exposed to fuel gas shall be made of materials that [fol- lowing 70-hr air aging at 212°F (100°C) in accordance with ASTM D 573] meet elongation, tensile, and hard- ness property requirements as specified in paras. 2.9.1.1 and 2.9.1.2.
2.9.1.1 Tensile tests shall be conducted in accor- dance with ASTM D 412. Three dumbbells shall be air aged 70 hr at 212°F (100°C) in accordance with ASTM D 573. The dumbbells shall have a thickness of 0.08 in. ± 0.008 in. (2 mm ± 0.2 mm). The average of the three individual tests for the aged dumbbells shall exceed 60% retention of ultimate elongation and 60% retention of tensile strength at break. The average of the three individual tests for the nonaged dumbbells shall be the basis for the percent calculation.
2.9.1.2 Hardness tests shall be conducted using specimens in accordance with ASTM D 395, Type 2. Three specimens shall be air aged 70 hr at 212°F (100°C) in accordance with ASTM D 573. The average of the three individual tests for the aged specimens shall not show a hardness change of more than ±10 Shore A hard- ness points relative to the average hardness of the non- aged specimens.
2.9.2 Swell Tests. Elastomer parts that are exposed to fuel gas shall be made from materials that after 70-hr exposure to N-hexane at 74°F (23°C), in accordance with ASTM D 471, meet the volume change, elongation, and tensile property requirements as specified in paras. 2.9.2.1 and 2.9.2.2.
2.9.2.1 Volume change tests shall be conducted using six specimens in accordance with ASTM D 471, Section
8. Three specimens shall be exposed for 70 hr at 74°F(23°C) inN-hexane inaccordance withASTMD 471. The average of the three N-hexane tests shall not show an increase in volume of more than 1%. The average of the three tests for nonaged specimens shall be the basis for the percent retention calculation.
2.9.2.2 Tensile tests shall be conducted on six dumbbells in accordance with ASTM D 412. Three of the tensile tests shall be conducted on dumbbells exposed in N-hexane for 70 hr at 74°F (23°C) in accordance with