Valve Seat Hardness

[Joesteam]

I am not very knowlegable in this area, so please be kind.

I am working with specifying engineers and they have a grandfathered specification for stellited valve plugs and seats for 200 psig steam service (district steam = dirty & wet) as an overlay on 316 SS material.

I have a valve with hardened 416 SS material that the manufacturer says is plenty hard and robust for this application.

I am thinking maybe that the stellite is a bit harder, however since it is just a overlay there may be problems with this in the long run. I would like to have the engineer at least allow the hardened 416, it would save the customers money and lead time.

Any ideas??

 

[insult2injury]

For many applications, 400 series stainless is sufficient and has been a standard offering for many valve manufacturers. Is the 416SS hardened through a nitriding process? If so, once that finite layer wears through, what can be done to repair the valve?

I2I

 

[Joesteam]

I believe the 416 is heat treated for hardness, the manufacturer data says 'hardened to 38 HRC' where an alternate trim is 316SS with CrCo-A hardfacing alloy.

 

[JLSeagull]

N08367, Alloy 6, B 688 is commonly used for errosive applications. Some manufacturers avoid the trade name such as Stellite, Haynes, Stoody Deloro, etc. Deloro Stellite covers a family of alloys.