17-4 PH SS material for valve stem

[Erkamal]

Hi All,

i have designed choke valve.

As per NACE MR 0175-2009. in table A.27, i can not use 17 -4 PH ss material for body and bonneet,

i am going to use for valve stem . but i am little confuse for that . can i use 17-4 PH ss for ste, or not?

ragards
Kamlesh

 

[SPDL310]

I wouldn't recommend it for a stem material unless all wetted areas of the stem are inlayed with a CRA. Some material that meet MR 0175 such as 4130 are still susceptible to high corrosion rates in sour service and should still be inlayed on all wetted surfaces in order to reduce corrosion.

 

[jbeckhou]

Man do y-all just make stuff up? AISI 4130 has no NACE limit and can be used on any part of a valve, ie, bonnet, body, stem, seat, gate without overlay. AISI 4130 is the most common used material used for API valves and chokes. You would NEVER want to weld inconel to 17-4, you would just use inconel material. How would you overlay the threads on a 17-4 stem? Again 17-4 is one of the most common used material for stems!!!

Erkamal
You can use 17-4 from table A.27 if you design input meets the guidelines of table A.27.

Petrotrim Services, LLC

http://www.petrotrim.com

 

[OGMetEngr]

17-4 has been used often for stems, they have also failed often. I wouldn't recommend welding 17-4 either. Depending on other factors, a CRA would probably be a better choice if high strength, NACE compliance, and localized corrosion resistance is needed. 17-4 has pitting/crevice corrosion resistance on par with 316. Also NACE is about to put further restrictions on the use of 17-4, and many oil companies just plain dislike the material.

As for using 4130 for any part of a valve, I wouldn't recommend that either. Any sealing surface that isn't overlaid will have a short life. Also, although 4130 has no defined "limit" at which cracking becomes a concern (provided all NACE hardness, etc. requirements are met), general corrosion would become a concern in plenty of situations.

 

[ricklts]

all,

maybe I'm just old school, but there must be several hundred thousand API 6A valves, chokes, and X-Mas trees in service in NACE and mildly corrosive service for the last 50 years. Only recently, with the advent of various injection chemicals and higher temperature service conditions has interest in CRA cladding become prevalent. Many customers disallow 17-4 as stem materials, requiring one of the Ni alloys. Just go with it, the costing isn't that much higher these days.

Rick

 

[jaydeep29]

Which API material class requirements for choke valve.
i.e.:- Here is standard for (EE class & temp.-U) Body and Bonnet AISI 4130 material.Needle material PH 17-4 SS & Hard alloy on stem tip.And orifice/Bean/seat form pressure dope 1500 use SS 316,pressure drop +2000 use tungsten carbide.

My Motto: Keep calm and never give up.