×
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

SA-335 Grade P12 and P22
3

SA-335 Grade P12 and P22

SA-335 Grade P12 and P22

(OP)
hi all,

what is the main practical difference between these two alloys:
1-  SA-335 Grade P12 (USA / ASME) Cr(0.8-1.2) Mo(0.44-0.65)
2-  SA-335 Grade P22 (USA / ASME) Cr(1.9-2.6) Mo(0.8-1.1)

Is it possible to substitute the second item with first one?
We are going to use them in boilers?

thanks a million

RE: SA-335 Grade P12 and P22

The main difference between these alloys is the allowable stress values, per ASME Section II, Part D;
Grade P22 has generally, at high temperature, an higher allowable stress compare with P12. In general you cannot simply substitute a pipe in grade P22 with an identical one in grade P12.
It's maily depending from the design temperature.

RE: SA-335 Grade P12 and P22

Other differences are cost, welding procedure, thermal conductivity.

If you are buildig an enire boiler, there may be cost savings by substituting T23 for all t22, t11, t12 and other light alloy tubes, as one scheduled furnace run by the mill for a single large T23 order may be cheaper than the smaller mill runs for the other alloys.  

RE: SA-335 Grade P12 and P22

One would almost never substitute P12 for P22 due to the greater design allowable stress at temperature of the P22. P11 and P12 are essentially interchangeable.  

RE: SA-335 Grade P12 and P22

As Stan points out the allowable stress/temperatures are significantly different. Also the ASME PREheat/PWHT are different. Also there is some difference in resistance to high temperature hydrogen attack, if that is a consideration. In my experiece P12 was unusual, P11 more common. These alloys; 1 1/4 Cr; 1/2 Mo and 2 1/4 Cr ;1 Mo are the workhorses of the petroleum/hydrotreating industry.

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