×
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

B31.3 Allowable Stress for High Pressure Piping

B31.3 Allowable Stress for High Pressure Piping

B31.3 Allowable Stress for High Pressure Piping

(OP)
I am calculating the W.T. for 7" OD 10,000# prssure piping using 4130 mechanical tubing.  Unless I am misunderstanding B31.3, Section K302.3.2, it appears that it is acceptable to use 2/3 the SMYS for the allowable stress.  However, everyone I have conferred with uses 2/3 the SMYS or 1/3 the tensile, whichever is less.  Am I missing something in B31.3 that says I have to use the lower of the two?  Even most of the allowable stress values given for the materials in Table K-1 use 2/3 SMYS.  The piping system I am designing will be operating at about 75 F.  Please help.

RE: B31.3 Allowable Stress for High Pressure Piping

Normal piping per B31.3 use lower of 2/3Yield and 1/3 of the tensile , as per par. 302.3.2.
High pressure piping is per par. K302.3.2 , the lower of 2/3 Sy and 2/3Syt.

RE: B31.3 Allowable Stress for High Pressure Piping

(OP)
Thanks for the response ijzer.  But what worries me about that is for higher pressures, the safety factor is actually decreasing because 2/3 yield is greater than 1/3 tensile.

The pipe I am considering (I have the MTR's) is 7" OD x .9375 W.T., 4130, 104,600 TS, 80,900 YS.  As you can see, which of the two allowable stresses you choose can make a significant difference in determining if the tubing will be "rated" for 10,000#.

RE: B31.3 Allowable Stress for High Pressure Piping

TXLSUCHE,
          Suggest you post this in the "Piping and Fluid Mechanics engineering" Forum or the "ASME(Mechanical) Code Issues" forum.

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