×
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

Straightness tolerance

Straightness tolerance

Straightness tolerance

(OP)
Dear all ;
According to ASME B31.3 what is the tolerance of piping straightness for a welded c.s. pipeline 1 km long
Thanks in advance

RE: Straightness tolerance

31.3 is a piping code not a pipeline one. There are specs for individual pipes but I don't recall one for the pipeline per se. Usually written in the construction specification. Maybe 1m horizontal from the straight line?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Straightness tolerance

The beginning and the end.
Two points make a straight line.

Reaction to change doesn't stop it smile

RE: Straightness tolerance

Like beauty, "straightness" is in the eye of the beholder.

Some locations and pipes will accommodate significant horizontal shifts and zig zags, others will be laser line straight.

Not everything is written in codes....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Straightness tolerance

(OP)
Thank you so much, but how can you accept or reject?

RE: Straightness tolerance

What is written in the construction specification??

If nothing then it becomes a judgement call. As said, for a line of that length, I would place a maximum of 1m away from a notional dead straight line or a maximum of 1 degree at any one point in terms of deflection.

What have you got?

do you have any pictures you can share?

you give us very little to go on here.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Straightness tolerance

I have not seen any specification on alignment tolerance in the lateral dimension, as generally anywhere within the trench, as long as it is with clearance sufficient for construction between pipe and trench sidewall and as long as the trench is within the right of way, is acceptable. However in the vertical dimension tolerance can be critical for gravity flow lines. Tolerance, if not defined specifically, can be inferred by the dimensions shown on the drawing. If an invert elevation is given as 100.05 ft, then the actual measured elevation would be made to one more decimal place and the value would have to fall within 100.045 ft and 100.055 ft, any of which would round off to 100.05 ft.

Reaction to change doesn't stop it smile

RE: Straightness tolerance

The best one I liked was when someone tried to convince me that he could use 3 degree mitre bends instead of cold bends because 3 degrees wasn't officially considered a mitre bend.... So if someone wasn't good at cutting pipe ends it could look rather jagged. ...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Straightness tolerance

(OP)
Thank you so much for responding but to be more specific the line is rested on supports and these supports must be on the same level but actually some of intermediate supports where fallen due to the fall of soil beneath it resulting in deferent levels in the horizontal direction causing like a small zig-zag shape in the horizontal direction as mentioned before because of elasticity so is there any tolerance in that knowing that this line pressure is 15 bar and containing desel fuel
With my respect to all of you

RE: Straightness tolerance

If it's not touching another pipe, or leaking, I wouldn't get too concerned about "snaking" in the lateral direction. Snaking actually lowers the stress.

Loss of support is another problem. Check the stresses in the line, using the deflected shape. Do the lines need to be continuously drained.

Reaction to change doesn't stop it smile

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