UL-429:2013 pdf free download – STANDARD FOR SAFETY Electrically Operated Valves.
6.3.4 External seal parts, and operating parts of safety valves affecting the closing of the valve and made of synthetic rubber shall not crack or show visible evidence of deterioration after being subjected to hand flexing following exposure as specified in the accelerated air-oven aging test in the Standard for Gaskets and Seals, UL 157. The oven temperature is based on the maximum normal operating (service) temperature of the seal or operating part. The oven temperature shall not be less than 60°C (140°F).
Exception No. 1: Oxygen bomb test for valves rated for oxygen service.
Exception No. 2: When a synthetic rubber material only used as a static seal cracks or shows visible evidence of deterioration following exposure as specified in the accelerated air-oven aging test, new samples of the synthetic rubber material are to be tested in the complete valve assembly, or as an alternative, new samples of the synthetic rubber material are to be tested in a test setup, which simulates the seal or gasket in the valve. After the accelerated air-oven aging testing, the samples shall comply with the requirements for the External Leakage Test, Section 29 and the Hydrostatic Strength Test, Section 34. For accelerated air-oven aging testing on the valve assembly, other seals or gaskets for which the valve assembly oven aging test is not intended, may be removed from the valve assembly before the accelerated air-oven aging test and then installed prior to the External Leakage Test and the Hydrostatic Strength Test.
6.3.5 External seal parts, and operating parts of safety valves affecting the closing of the valve made of a thermoplastic material in contact with one of the fluids listed in Table 6.1 shall be subjected to the Dimensional Stability Test in Section 51.
6.3.6 External seal parts, and operating parts of safety valves affecting the closing of the valve made of elastomeric and synthetic rubber material in contact with Hydrogen gas at pressures greater than 75 psig shall be subjected to the Accelerated Hydrogen-Pressure Aging Test, Section 54.
6.3.7 External seal parts, and operating parts of safety valves affecting the closing of the valve made of a composite gasket material shall be subjected to Tensile Strength Test as-received and following immersions in the test fluids indicated in Table 6.1 and air oven aging conditioning specified in 6.3.4, and the retention properties shall not be less than 50% of the as-received values. The Tensile Strength test method is as described in the Standard for Gaskets and Seals, UL 157.
6.4 Corrosion protection
6.4.1 Metallic parts shall be resistant to atmospheric corrosion and degradation by the fluid it normally contacts in service when corrosion of such parts may cause external leakage, or prevent a safety valve from functioning as a safety shutoff.
6.4.2 If atmospheric corrosion of a ferrous part will interfere with the intended function of a valve, the part shall be of a corrosion-resistant material or be provided with a corrosion-resistant protective coating.
6.5 Insulating materials
6.5.1 A material that is used for the direct support of an uninsulated live part shall comply with the Relative Thermal Index (RTI)， Hot Wire lgnition (HWI)， High-Current-Arc Resistance to lgnition (HAI)， Comparative Tracking Index (CTI) values indicated in Table 6.2. A material is in direct support of an uninsulated live part when.