API St 589:1998 pdf download.Fire Test for Evaluation of Valve Stem Packing
1 Scope
1.1 This standard covers the requirements for testing and evaluating the performance of valve stem packing when it is exposed to a Þre as deÞned in this standard. Packing may be a combination or an arrangement of more than one material. The test procedure in this standard simulates circumstances that impose severe demands on valve stem packing.
1.2 The requirements described in this standard establish performance limits for evaluating valve stem packing acceptability. Note: The maximum acceptable leakage rates given in this standard are for the test temperatures and pressures speciÞed. Leakage rates of valves in service during and after an actual Þre may be substan- tially different.
3 Fixture for Fire Test
3.1 Packing shall be evaluated either in a carbon steel, Class 300, NPS 6,8,10, or 12 gate valve conforming to API Standard 600 or in a test Þxture. If a test Þxture is used, it shall include a vessel representative of a carbon steel, Class 300 gate valve body and bonnet and shall have integrally attached a matching simulated stufÞng box and a stem. The simulated stufÞng box and stem shall have dimensions as speciÞed in API Standard 600. Gland, gland ßange, and gland bolting shall also be representative of those in a carbon steel, Class 300 gate valve of the simulated NPS. The simulated stem shall be capable of traveling at least 150 mm (6 inches) through the simulated stufÞng box. In either case, means shall be provided to prevent stem rotation. Any subsequent refer- ence to test valve means valve or test Þxture. To assure that the test pressure reaches the packing area of the test valve and to assure uniformity, the following diamet- rical clearances in the packing area have been established: 1. Stem outside diameter to backseat bushing bore, 1.2 mm ± 0.25 mm (0.050 inch ±0.010 inch); 2. Stem outside diameter to gland bore, 1.2 mm ±0.20 mm (0.050 inch ±0.010 inch); and 3. Gland outside diameter to stufÞng box bore, 1.2 mm ± 0.25 mm (0.050 inch ± 0.010 inch). The test valve (or Þxure) shall have the following surface Þnishes in the packing area: stem outside diameter, 0.8 micrometer (32 microinches) maximum roughness (in accor- dance with ASME B46.1); and the stufÞng box bore 3.1 micrometers (125 microinches) maximum roughness. Dimensions and tolerances to be reconÞrmed before use of the test valve (or Þxture) for another test.
API St 589:1998 pdf download
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