×
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

wall thickness tolerances for ferritic seamless pipe for natural gas

wall thickness tolerances for ferritic seamless pipe for natural gas

wall thickness tolerances for ferritic seamless pipe for natural gas

(OP)
Does anybody know what are the tolerances for wall thickness of ferritic seamless pipe use to transport natural gas? Somebody told me that it is -12.5% and +20.0%, is this correct?
Thank you,
Jaime L

RE: wall thickness tolerances for ferritic seamless pipe for natural gas

Hi Jaime,
Half is true, the first half. In the calculation of the available reinforcement, you deduct the 12.5% of "mill tolerance" and also deduct the corrosion allowance if applicable.
cheers,
gr2vessels

RE: wall thickness tolerances for ferritic seamless pipe for natural gas

The 12.5% is a standard B31 code allowance for extruded seamless pipe.However, modern extrusion methods in Japan and EU can provide much better wall tolerances than 12.5%.

In theory you can amke use of the better actual wall tolerance as follows:  another  code paragraph  also allows the design pressure to be set based on measured wall thickness, if a truly all inclusive survey of the entire pipe is the basis of the as -recieved wall thickness.

RE: wall thickness tolerances for ferritic seamless pipe for natural gas

The upper limit is technically set by total weight, and yes it could be as much as 20% if the stars lined up just right.

Get out the spec and read it.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: wall thickness tolerances for ferritic seamless pipe for natural gas

Yes, if you quote using API standard.

But you can ask for better tolerances and indeed the good mill can do it for you. But  you have to work out with mill to find a reasonable price and min purchase volume.

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