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!

*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.


API 570 T-MIN and MAWP with no pipe information

API 570 T-MIN and MAWP with no pipe information


I am currently working as an API pipe inspector on a loading dock. A majority of the piping is overwater. That being said besides the design pressure and operating temperature, the customer has absolutely no previous history on the piping. Therefore, I will calculate the MAWP and T-Min per API 570 and 574 in order to provide recommendations.

However I am not sure what the Stress value or Y coefficient should be since there is no information on the pipes, by the way all piping is carbon steel.

RE: API 570 T-MIN and MAWP with no pipe information


RE: API 570 T-MIN and MAWP with no pipe information

there are non destructive methods of positive metal identification that can tell you what the material is

RE: API 570 T-MIN and MAWP with no pipe information

Lacking any information a conservative and best endeavours approach could be followed, such as:

Select the lowest allowable stress from all carbon steel grades tabulated within the original design code;
Assume minimum NDT and select the appropriate weld quality/strength reduction factors;
Select a Y value consistent with carbon steel and the design temperature.

A first pass could be done on circumferential stress alone but there's also longitudinal stress that may be more onerous for MAWP and tmin - if you don't know what the piping loads are there is a routine in API 579 that you could follow, see the section on Supplemental Loads in Annex 2C.

RE: API 570 T-MIN and MAWP with no pipe information

BenStewart's advice is exactly what is recommended by API 570 Sec. 7.5. Also, I agree that longitudinal stress will likely govern. At a minimum, span calculations should be performed considering weight of piping, product, and insulation (if present). Also, structural minimum thicknesses outlined in API 574 should be considered.

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