Monday, October 20, 2014

Selecting a Stainless Steel Globe or Gate Valve

stainless steel industrial valve
Stainless steel valves
(courtesy of Aloyco)
Stainless steel globe and gate valves are available in materials including CF8M, CF3M, and CN7M (Alloy 20) and in broad pressure classes including Class 150, Class 300, Class 600, and 200 CWP.

Stainless steel valves are required in many applications found in pulp and paper, mining, chemical processing,  food processing, waste water, and fertilizer processing.

Care should be taken to select the most suitable valves for your service(s). Exact specification of each valve should be made to avoid possible ambiguity. When requesting quotations and/or ordering the product a fully adequate description should be made.

Selecting the Valve Size
Nominal size of the pipeline into which the valve will be placed must be determined.

Valve Material
The following facts should be considered in determining the correct valve material:
  • the medium or media which will be controlled
  • the temperature range of the line medium (media)
  • the pressure range to which the valve will be subjected
  • possible atmospheric conditions which may affect the valve
  • possible extraordinary stresses to which the valve will be subjected
  • safety standards and/or piping codes which must be met
Type of Valve
What is the control function of the valve? Each valve configuration has been developed to perform certain control functions. Do not expect one type of valve to perform all the valving jobs in a system.

Pressure-Temperature Ratings
Please pay careful attention that the pressure-temperature ratings of a particular valve are in keeping with the requirements of the service. Pay especially careful attention to the packing and gasket materials as this may limit the rating. Specify graphite or alternative packing and/or gasket materials as necessary to meet or exceed your service requirements.

Valve and Connections
Considerations as to pipeline integrity, future maintenance, corrosion factors, field assembly, weight and safety should be given in determining the method of connecting the valve in the pipeline.

Method of Operation
The means by which the valve is operated as supplied are shown for the valves in this catalog.

When Specifying, Confirm:
  1. Valve size.
  2. Pressure boundary material - metallurgy of the castings and components.
  3. Type of valve - gate, globe, check, etc.
  4. End connection including wall thickness of connecting pipe if weld end and any special flange facings or finishes.
  5. Any material deviations from standard - packing, gasket, bolting, etc.
  6. Any accessories such as acid shield, locking devices, chain operation, etc. 
  7. Manual or power actuators, please include details of requirements.