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Control Valve Body Materials

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The medium or substance flowing through a valve will often determine the type of valve body material. Some valve body materials are best suited for high temperature applications while others are best suited for their corrosion resistance to fluid substance still others are selected based on a low cost factor. Most times, manufacturers of valves will aid you in selecting the right valve for a given application after supplying the needed information.
Common Valve Body Materials:
Application Notes
 Bronze  Used for plumbing, heating and air-conditioning systems.
 Selected when line size is less than 3 inches
 Cast Iron  Majority of iron valves are made of cast iron.
 Used in many applications.
 Cast Iron has a temperature limit of 450 degree Fahrenheit
 Ductile  Iron  Also called nodular Iron. It has good corrosion resistance.
 Most often used in the Marine industry and for underground  pipelines.
 Ductile iron valves can be used in applications that experience  vibration and shock.
 Ductile iron has a temperature limit of 650 degree Fahrenheit.
 Steel  Steel valves can either be forged steel or cast steel. Forged  steel  valves are used when higher pressures and  temperatures are  required and the line size less than 2.5  inches.
 Cast Steel valves are used on line sizes over 2 inches when  higher pressures and temperatures demand the use of  carbon or  alloy steel

 Stainless  Steel  Stainless steel valves are used when any form of problem  is  expected with corrosion in carbon steels or when high  grade  surface finishes are needed for reducing or  eliminating  contamination problems.
 Stainless steel valves are widely used in chemical process,  petrochemical, pulp and paper, and electric utilities  industries.

 Thermoplastic  The chemical industry and many other industries make  wide use of thermoplastic-bodied valves.The two common  types of thermoplastic are in use namely:
 CPVC(Chlorinated polyvinyl chloride) and  PVC(polyvinyl  chloride).
 PVC is the most popular and can be used for more  applications than other plastics. It can only be used up to  140 degree Fahrenheit.
 CPVC is used in many high temperature applications.
 CPVC valves can service temperatures of 45 to 75 degree  Fahrenheit higher than PVC valves
 There is also TFE(Tetrafluoroetheylene)
 TFE is commonly used as seal material in quarter turn  valves such as the ball or plug valve.

Standard Control Valve Body Materials:
Valve body materials for most control valves fall under the basic standard types below:
Cast Material
 Application Notes
 Carbon  Steel ASTM  A216 Gr. WCB  For moderate services such as non-corrosive fluids.  Higher pressures and temperatures than cast iron. If  desired for extended high temperatures check the  relevant code for suitability
 Chrome-Moly Steel  ASTM A217 Gr. C5  Used for mildly corrosive fluids such as sea water,  oils. Resistant to erosion and creep at high  temperatures. Can be used to 595 degree  Celsius(1,100 degree F)
 Type 304 Stainless Steel  ASTM A351 Gr. CFB
 Used for oxidizing or very corrosive fluids. Can be      used above 540 degree C(1,000 degree F)
Type 316 Stainless Steel  ASTM A351 Gr. CF8M  Used for oxidizing or very corrosive fluids, resistant  to corrosion pitting and creep. Provides greater  strength than 304 SS
 Monel  ASTM A494 Gr. M35-1  Resistant to non-oxidizing acids. Used with seawater  and other mildly corrosive fluids at high temperatures.  Expensive in terms of cost.
 Hastelloy -C  ASTM A494 Gr. CW2N  Expensive
 Iron  ASTM A126 Class B  Inexpensive and non-ductile. Used for water and non-  corrosive liquids.
 Bronze  ASTM  B61 &  B62  ASTM B 61 typically used for valve trim. ASTM B  62  typically used for valve body. Can be used for  water and  dilute acid service. 

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