F51 DUPLEX + STELLITE or 17-4 PH STEEL 1

[GabrieleB]

I have to produce a data sheet for a globe valve in high chloride environment, i want to know if is better a disc in duplex F51 with stellite 6 hard facing or 17-4 PH (AISI 630) hardenable stainless steel.
Which is the cheaper solution? In my opinion the second one.
Is it advisable to use a 17-4 PH steel with a content of 160000 (160g/l) of chorides? Thanks in advance for your help

 

[rneill]

You don't mention other aspects of the service environment such as whether there is any H2S present in which case NACE MR0175/ISO 15156 Table A.27 might restrict the use of 17-4 PH steel.

 

[GabrieleB]

There isn't H2S content in the water, so we are not in Sour Service Condition. I appreciate your answer. In any case for me is very interesting to know which solution is cheaper for a 10" Ball Valve and the main difference beetwen these 2 technical solutions. Thanks for your collaboration.

 

[MikeMet]

I would go with the Stellite 6 which has good corrosion resistance in oxidizing environments and chlorides and is hard enough for a good sealing surface. We have used Stellite seats in valves in methylene chloride solutions for years with good experience. 17-4PH sst is susceptible to chloride stress corrosion cracking under the right conditions, so that would not be a good choice. Duplex is also a good choice, but not as hard as Stellite.

 

[hsbcn]

What pressure/temperature are we looking at?

Heather's focus: Alloy Valves Duplex Valves Super Duplex Valves Monel Valves Inconel Valves [link titanium-valves.com]Titanium Valves[/url] & 6 Moly Valves

 

[superweo]

If you are looking for a TSO valve, a ball valve with metal to metal seats (tungsten carbide coated) will never be tight but will admit a leakage according ISO 5208 rate B as maximum sealing, more often it will be ISO 5208 rate D.
Temp/pressure is important to know ehter you can use cast material vs forged which will make the valve cheaper.
Ciao