Ductile iron butterfly valves have higher ductile rating (thus, the name) and will conform more to the swaying. While ductile iron has good ratings for dampening, it is not as highly recommended as cast iron for use on loud or heavy machinery because it doesn’t soundproof as well and is not as durable when vibrated. 

The butterfly valves from ductile iron have similar chemical composition to the ones of Gray iron but special treatment in the casting process modifies the metallurgical structure yielding mechanical properties equal to carbon steel but retains the superior corrosion resistance in certain environments. This metallurgical structure change make it an ideal choice for butterfly valve bodies.

For higher mechanical shock resistance under high or Iow temperature, and better tensile strength and elongation characteristics than those of ordinary gray iron butterfly valves, ductiIe iron butterfly valves are highIy recommended for the following services, sometimes, in place of cast steel valves :

• ductile iron butterfly valves for piping for steam supply
• air conditioning and heating systems
• high-pressure gaseous service in general
• ductile iron butterfly valves for piping for poisonous gas service