×
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

ASME VIII _ HYDROTEST PRESSUREthread794-135893

ASME VIII _ HYDROTEST PRESSUREthread794-135893

ASME VIII _ HYDROTEST PRESSUREthread794-135893

(OP)
Just to clarify my understanding, when ASME updated the code on hydrotest pressure ratio to specify the minimum requirement of 1.3  what was the logic behind selecting 1.3 as the ratio, i recognise this is the minimum requirement and also that no upper limit for hydro is advised but what  precludes or not if the case may be, one from simply maintaining 1.5 as a ratio, do we have to prove or complete additional calculations to use a ratio of 1.5?

RE: ASME VIII _ HYDROTEST PRESSUREthread794-135893

You should do the calcs to prove that you are not exceeding the yield limits.

1.3 is used because we are increasing the allowable stress
used in calculations, effectively increasing stress in vessel.

RE: ASME VIII _ HYDROTEST PRESSUREthread794-135893

Plagiarizing myself from thread292-109371: 1998 Section VIII hydrotest pressure

The 1.5x hydro was changed to 1.3x with the increased allowable stresses introduced with the 1999 Addenda. Simply put, the stress during the hydrotest remains basically the same: The allowable stresses (those which were limited by ulitmate strength) increased from Sut/4 to Sut/3.5 and correspondingly the hydrotest was changed by the same ratio. 1.5*[3.5/4]=1.3. For example, a vessel built of SA516-70 (at 500°F or lower) material would have its circ stress brought up to about 1.5*17.5 = 26.25 ksi during the hydrotest. A vessel built to the 1999 or later addenda would have its circ stress brought up to about 1.3*20 = 26 ksi.

The post-construction hydrotesting requirement is up to the AI who may request a lower than VIII-1 hydro. In theory though, a 1.3xMAWP hydro would not meet VIII-1 for a vessel built to the 1998 or earlier addenda. It would not result in the stress in the vessel which it would have seen during the shop hydro. In this case, for the example in the above paragraph, the hydrotest circ stress would be only 1.3*17.5 = 22.75 ksi.

jt

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