×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Material strength : SS316 for class 2500 valves

Material strength : SS316 for class 2500 valves

Material strength : SS316 for class 2500 valves

(OP)
Hello everybody.

I am a valve designer and I am facing a concern about the use of SS 316 (or other material whith the same strength) for class 2500 valves (or higher).  When I use a FEA software to compute the body, I often reach stresses which overgo the 316 yield strength, for sizes bigger than 2 in.

Is it common to choose such a material for such a pressure ?
Has anybody ever faced such a problem ?

Or other materials, with higher strength, have to be advised ?

Thank you

RE: Material strength : SS316 for class 2500 valves

What pressures are you using?  
Typically, allowable pressures for SS flanges are lower than for other materials.
(see B16.5)

RE: Material strength : SS316 for class 2500 valves

(OP)
class 2500 correspond to 431 bars as working pressure

RE: Material strength : SS316 for class 2500 valves

In the offshore market for ANSI 2500# and API 10,000#, I've used a number of materials.  Good options for strenght vs. weight seems to be 6Mo material (ANSI A182-F44).  Also the Duplex and Super duplex grades of stainlees steel (F51 & F53/F55) are also common.  I have also used A350-LF2 with an inconel 625 weld overlay on whetted areas for large valves.

The other thing you will likely have to look at is increasing the wall thickness of your valves considerably if you need to continue to use 316.

Andy

RE: Material strength : SS316 for class 2500 valves

(OP)
Thank you both.

I know that I have to increase the wall thickness.  It is possible radially.  But in the other direction I am limited by the face to face... Perhaps have I to fix a bigger face to face.  

RE: Material strength : SS316 for class 2500 valves

What kind of valve are you designing? For ball valves at these pressures, I haven't noticed any problems with face to face.

Andy

RE: Material strength : SS316 for class 2500 valves

(OP)
A trunnion mounted ball valve.

RE: Material strength : SS316 for class 2500 valves

Are you using the wall thickness per ANSI/ASME B16.34?

RE: Material strength : SS316 for class 2500 valves

(OP)
Yes.  But is it sufficient to guarantee the resistance ?  

We always verify the stress thanks to FEA. And depending on the material used, the stress can be too high... even if the minimum wall thickness is repected.  

RE: Material strength : SS316 for class 2500 valves

I think that for most applications, especially in chlorides, the use of duplex materials offers substantial improvement in yield strength.  With the present price of nickel, etc. the use of 2205 duplex may make sense - however, I would carefully check qualifications of suppliers.  The material is prone to sigma phase embrittlement if incorrectly heat treated.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources