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


underground pipeline

underground pipeline

underground pipeline

Does underground piping always require pipe stress analysis, even if it is an ambient pipeline?   

RE: underground pipeline

That depends on the Client, the project specification, and other conditions.  For example, a 2000 psi buried line would be a little dangerous, even at ambient.

Richard Ay

RE: underground pipeline

Ambient is 100F in the summer and 0 in the winter.  That can be a lot of stress and even more force, if the area of steel is high, even without any pressure at all.

"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

RE: underground pipeline

            As Biginch point's out ambient conditions can vary. Use your experience and the physical conditions to which the pipe will be subject to determine if a formal stress analysis is required or if you are unsure engage a Company who can make a judgement based on the physical conditions to which the pipeline is subjected to.

RE: underground pipeline

Thanks for the advice, everyone.  The deciding factor for me was the fact that this installation will include booster pumps.  I'll need to do system stress analysis to give me the loads for the component analysis (API 610 nozzle loads).

RE: underground pipeline

The rule of thumb I usually follow is this:

Take the specified minimum yield strength of the pipe in MPa and divide by six.  If the difference between installation temperature and operating temperature in degrees Celsius is greater than that, then not only is stress analysis mandatory, but you might find it difficult to "pass".

In other words:

For [(SMYS/6), MPa] < [(Th - Ti), C], stress analysis is mandatory



RE: underground pipeline

SNORGY (Mechanical)

Please provice detail reference reqard to

For [(SMYS/6), MPa] < [(Th - Ti), C], stress analysis is mandatory  

which reference book?

Leonard S. Thill

RE: underground pipeline

        SNORGY has already said it is a "Rule of Thumb" he utilises - maybe there is no reference to a book. Not everyone has a list of books but use judgement!!!

RE: underground pipeline

It comes from algebraic rearrangement of the equations in CSA Z662 Clause 4 that relate to the maximum allowable combined longitudinal stresses.  It is at about that ratio, for a gas pipeline in a Class Location 1, that those equations begin to dominate over hoop stress towards computing the design wall thickness.



RE: underground pipeline

Its obvious that is also very close to 0.9 SMYS - Hoop Stress Allowable in B31.4 & .8 Class 1, of 0.72, but I was too lazy to work out the relation to the axial compressive temperature stress at "Th-Ti,C" to see if the rule of thumb was actually valid IMO or not.  It certainly looked good enough to have a reasonable expectation of being true, which is all you really need for a "rule of thumb".

"The problem isn't finding the solution, its trying to get to the real question." BigInch

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!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close