+1 vote

3 Answers

+1 vote
answered May 30, 2015 by josvanden (3,240 points) | selected Feb 23 by odadmin
Best answer

The selection should comply with the following:

  • Materials should be suitable for the fluid service and for the maximum and minimum fluid design temperatures to which these components will be exposed.  As a minimum, stem packing for valves in hydrocarbon or steam service should be suitable for 1000°F (538°C) process temperature.
  • For all non-oxidizing environments and for oxidizing environments, less than or equal to 1000°F (538°C) process temperature, pure graphite (minimum 95 percent carbon content) packing and interlaced braided graphite end retainer rings should be used unless specified.  Density of graphite preformed rings should be 70 to 90 lb/ft3 (1120 to 1440 kg/m3).  All packing rings should contain corrosion inhibitor.
0 votes
answered Jun 6, 2015 by AngelPenavega (1,025 points)
Except for certain acid services and oxygen, fire-tested valve stem packing materials should be used in flammable, combustible or dangerous material services.
0 votes
answered Jul 1, 2015 by lonstruthers (445 points)
17-4 Precipitation Hardening stainless steel valve stems, shafts, hinge pins and their integral components, should not be used for design temperatures greater than 750°F (400°C).  17-4PH stainless steel is an acceptable substitute for 13-Cr when the material and heat treatment comply with ASTM A 564/A 564M, Type 630.