Butterfly Valve Material

[Lucycn]

Who can tell me whether I can use Cast Iron for Butterfly Valve Body for PN25 DN500-1600? do you have better material to recommend to me? what's the advantage of the material which you recommend?
Your answer will be high appreciated.

 

[mqas]

The use of cast iron as the body material is purely down to the designer of the valve. i.e. only the manufacturer can advise whether they have taken the SMYS etc. of the cast iron into account for the design pressures and temperatures.

 

[Lucycn]

Hi mqas,
thanks for your reply, would you tell me what's meaning of "SMYS"? if you are designer can you use cast iron as the body material to design PN25 DN500-1600 for drinking water medium?
Thanks in advance.

 

[gervanderpers]

In general youll find for full rating PN25 valves Ductile iron or steel.grey cast iron in general for lower pressures

 

[mqas]

Lucycn

Sorry SMYS = Specified Minimum Yield Stress

 

[cranekiran]

Hi,

Yes,You can use Cast iron as the Body material for the Butterfly valve in Question.

Refer BS:5155 & BS:4504 SEC.1&2.

Just for advice,The above standards I have mentioned have been or are in the process of withdrawal stage.But there is no harm if you can still get a copy of that.

For BS:5155 It is BS-EN-593 now for Butterfly valves,For the BS:4504 It is still in the Draft format.

Bye!!

 

[Lucycn]

Hi gervanderpers,
thanks for your answer, I got the same idea from our engineer, but our customer request use cast iron, so I want to know who has the experience of using cast iron for PN 25 as valve body, how about the result.

 

[Lucycn]

hi mqas,
thanks for your explanation, as usual SMYS is defined by manufacturer or by user?

 

[NGiLuzzu]

For general principles of materials selection, also see Thread408-66513 in this Forum...
Bye, 'NGL

 

[Lucycn]

Hi cranekiran,
Thanks for your reply, I check the standard BS EN 593, it is defined the body material acc. to EN 1503 but I cannot find EN 1503 on hand. BS 4504 is defined the flange material but acc. to ASTM/ANSI B16.5a for the material of flange is Steel instead of Cast iron for 150psi(PN20) and above.

 

[Lucycn]

hi anegri,
I have check the Forum which you mentioned, it is general principle of material selection but I cannot find the defined for PN25 butterfly valve body material using the Cast iron.

 

[unsy]

You can use cast iron for the design of a pressure vessel such as a Butterfly valve and the sizes and pressure you mentioned and this has been done by many valve manufactures, however it is not possible to generalise. You must look at more than just the pressure loading, piping end loads and operting torques must be considered. As you are looking at a brittle material you need to consider any potential shock that the valve could suffer.In summary if the valve is designed correctly then you will have no problems with cast iron.

To look at the mechnaical properties of cast iron you could reference BS EN 1561 and have a look through the grades.

Another possibility could be SG Iron which offers better mechanicals but at a cost.

 

[Lucycn]

hi unsy,
thanks for your answer, yes there more conditions we should to consider for design, every material has its advantage and disadvantage when we use it. regarding my question, some people agree me to use cast iron, others suggest me to use carbon steel, as you mentioned, if the valve is designed correctly the cast iron will be no problem. we will try both of materials. Thanks.