×
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 B16.9 Burst Pressure Testing of Bends
2

ASME B16.9 Burst Pressure Testing of Bends

ASME B16.9 Burst Pressure Testing of Bends

(OP)
49 CFR 195 "Pipelines Facilities for Transportation of Hazardous Liquids or Carbon Dioxide" states that "Butt welding type fittings must meet the bursting strength requirements of ASME B16.9".  Further down, 49 CFR 195 allows changes in pipe direction by bending pipe.  ASME B31.4 "Pipeline Transportation systems for Liquid Hydrocarbons and Other Liquids" also has similar language.  ASME B16.9 applies to "Factory Made Wrought Buttwelding Fittings" and states that fabricators of wrought fittings can the specified burst testing method to qualify the fitting design.  If, during the construction of a buried steel fuel pipeline, a 90° change in direction is required, and the Contractor has a fabricator make a 90°bend by bending pipe, does this bursting test requirement still apply?  The pipe being used to fabricate the bend is thicker than the straight pipe being used; after bending, the wall thickness of the bend will exceed that of the adjacent pipe; and calculations per ASME B31.3 show that the wall thickness of the bend is abotu 4 times that required.

RE: ASME B16.9 Burst Pressure Testing of Bends

ChrisFK,

The fittings and bends should have equal or better strength compared to the pipe, in most piping systems.  Bending always has some wall thinning associated with the forming, so fabrication starts with thicker wall material.  Stress intensification factors applied to bends and fittings will result in thicker wall requirements compared to the straight pipe.  Bend radius affects the stress intensification factor - a 1D radius has higher SIF than a 5D bend.  If the real estate is avaiable for a 10D radius bend, then the pipe wall thinning might be small enough to use the same thickness as the straight pipe   

RE: ASME B16.9 Burst Pressure Testing of Bends

It is a concern of the safety and quality (reliability) of the home made fittings.
Typically, the manifacturer has to follow the procedure to fabricate the pipe bends and perform the test. So, it could make sure the quality of the bends is the same.
You may have responsibility as a facilioty owner to make sure it meet the requirements not only the wall thickness but the shape, smoot surface, testing, etc. Also, you want to consider what if it bursted during service, how much damage it will cause?
The bottom line is that it is an engineering decision and you don't want to cause any problem later on just because of it.

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