API St 622-2018 pdf download.Type Testing of Process Valve Packing for Fugitive Emissions.
1 Scope This standard specifies the requirements for comparative testing of valve stem packing for process applications where fugitive emissions are a consideration. Packing(s) shall be suitable for use at service temperatures –29 °C to 538 °C (–20 °F to 1000 °F). Factors affecting fugitive emissions performance that are considered by this standard include temperature, pressure, thermal and mechanical cycling, and corrosion. This standard is not intended to replace type testing of valve assemblies or valve production testing. This standard establishes requirements and parameters for the following tests: a) fugitive emissions; b) corrosion; and c) packing material composition and properties. Test methods apply to packing for use in on-off valves with the following stem motion(s): a) rising stem; b) rotating stem; or c) rising and rotating stem. 2 Normative References The following standards contain provisions that, through reference in this text, constitute provisions of this API standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. ASME B16.5 1 , Pipe Flanges and Flanged Fittings ASME B16.20, Metallic Gaskets for Pipe Flanges—Ring Joint, Spiral-wound, and Jacketed ASTM D512, Standard Test Methods for Chloride Ion in Water ASTM D1179, Standard Test Methods for Fluoride Ion in Water ASTM D4327, Standard Test Method for Anions in Water by Suppressed Ion Chromatography MSS 2 SP-120, Flexible Graphite Packing System for Rising Stem Steel Valves
3 Terms and Definitions For the purposes of this standard, the following definitions shall apply. 3.1 anti-extrusion ring A ring of packing used at one or both ends of a packing set to prevent extrusion of packing material into clearances. 3.2 ambient temperature Temperature that is between 15 °C (59 °F) to 40 °C (104 °F). 3.3 axial In the direction of a shaft or stem axis. 3.4 bolt torque The amount of twisting or turning effort (expressed as Nm, lbf-ft, or lbf-in.) required to turn the nuts on a gland flange; commonly used to determine the load that a gland flange exerts on a valve packing set. 3.5 braided packing Packing typically constructed of intertwining strands of synthetic or natural fibers. Strands may consist of yarn or filaments, and may also include metallic materials. 3.6 bushing Cylindrical spacer used to take up excess space in a stuffing box. 3.7 corrosion inhibitor An ingredient added to packing that decreases the potential for galvanic corrosion in the stuffing box. Corrosion inhibitors may be classified as either passive or active. 3.8 die-formed packing A valve stem packing typically constructed from ribbons of graphite tape or braided packing that has been subjected to pre-compression with tooling of a specific geometry. This process changes the shape and density of the material from its original free shape and natural density to a defined shape and higher density. 3.9 emissions Gaseous leak given off by a piece of equipment. Used in reference to volatile organic hydrocarbons (VOCs) and expressed in parts per million volumetric (ppmv or ppm). 3.10 galvanic corrosion An electro-chemical reaction that may occur between a metal and a material of a different chemical nobility, such as another metal, carbon, or graphite when both materials are exposed to an electrically conductive media. 3.11 gland A movable part that is inserted into a stuffing box to compress a packing set or packing ring.
3.12 gland flange The component used to retain the gland within the stuffing box and provide compression of the gland into the packing/stem seal to create load. The gland flange shall have two holes to receive the gland bolting. Slots for gland flange bolts shall not be used. The gland and gland flange shall be self-aligning. The gland shall have a shoulder at its outer edge so as to prevent complete entry of the gland into the packing box. 3.13 gland load The amount of load applied to a packing set. 3.14 gland flange stud A threaded rod or eye-bolt extending from a valve body against which the gland flange is tightened to compress a packing set. 3.15 leak Measurable amount of test fluid escaping from the test gland. 3.16 leak rate The quantity of test fluid passing through (or around) a seal in a given period of time. 3.17 mechanical cycle A motion of the stem simulating the movement of a valve obturator (such as disc or ball) from the fully closed position to the fully open position, and returning to the fully closed position. See also: stroke. 3.18 packing set A grouping of individual packing rings designed to fill the cavity of the valve stuffing box, with or without anti- extrusion rings. 3.19 pitting Surface cavities that occur on a metal as a result of galvanic corrosion. See also: galvanic corrosion.