Historical
MSS SP-121-2006
Qualification Testing Methods for Stem Packing for Rising Stem Steel Valves
- This Standard Practice provides procedures and guidelines for testing and evaluation of valve stem packing materials and material combinations. This testing provides qualification by verifying the adequacy of specific packing material combinations for service within defined limits of size, pressure, temperature, and cyclic duty. Such specific combinations generally represent products of individual manufacturers, although generic qualification of raw materials may be demonstrable in certain cases.
- It is intended that this Standard Practice apply to qualification of stem packings for Class 150 through 4500 ASME B16.34 or equivalent steel or special alloy valves (including intermediate classes and Standard, Special, and Limited Class ratings) with rotating/rising and non-rotating/rising stems, as traditionally used in globe and gate valves. Other valve stem types (e.g. quarter-turn) may involve additional considerations not within the scope of this Standard Practice.
- The requirements herein apply to qualification of traditional compression packings. Rod seal elements such as "O" rings, "V" rings, and similar proprietary seals are not within the scope.
- Stem packings may be prequalified by experience or by test programs conducted prior to publication of this Standard Practice if a qualification report is prepared based on documented evidence.
- This Standard Practice is intended to provide experimental qualification of packing materials and materials combinations for service with water, steam, and other common liquids, vapors, and gases. Some of the procedures identified in detail use water and steam as test fluids, but air or nitrogen may also be used with appropriate modifications in testing and data acquisition methods.
Content Provider
Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. [mss]
