Ball material (Ball Valve)

[PAN]

If the project specification requires A105+ENP (Electroless Nickel Plating) for ball material, can we use A182-F304?

Please advise me about pros and con.

 

[PeterIgg]

Pan,
It really depends on the client. Many clients will specify A105/ENP because they believe it to be a more cost effective option than a full stainless steel ball. The other advantage I see is that there is no plating to come off! Whilst the surface hardness of the ENP is quite high, the strength of the substrate is often the limiting factor, especially in the instance where line scale, sand or similar is caught between ball and seat. Once the ENP coating is compromised a failure will not be long in coming.

The potential downside, other than perhaps material compatibility, is that 304 is weaker than steel so the sealing surface may be more prone to degredation and the stem drive may need to be greater in size to accommodate this.

 

[JimCasey]

Also it depends what is running thru the valve. A105 is a little harder than 304 as peter stated, so something noncorrosive will see better service with the steel ball. ENP has a very low coefficient of friction in addition to the hardness Peter mentioned, so it reduces the valve's torque/actuator price. This is significant because it is not unusual for the actuator to be more expensive than the valve.
One other thing to consider is the seat material. ENP/Steel may resist galling much better than 304 if running against metal (particularly 300-series stainless) seats.

 

[PAN]

Thanks PeterIgg and JimCasey,

This is manual operate valve size 4" for compressed air service. If you have further comment, please advise me.

 

[JimCasey]

Compressed air service is almost guaranteed to contain rusty water. I think you will like the SS ball better and the ENP will halp resist scratching from the rust particles. Reinforced TFE composite seats will outperform virgin TFE seats.

 

[1944jml]

Which will be the material trimp for a valve in gsasoline.ACPM and nafta service? Thank you.

 

[JimCasey]

Gasoline and Naptha are pretty closely related. Most of the TFE composite seats will work without swelling, but I'd think you'd want a valve with a firesafe sticker on it and either pneumatic spring-failsafe actuation or at least a deadman's handle.