×
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

B31.X Code Implications of "Roping"

B31.X Code Implications of "Roping"

B31.X Code Implications of "Roping"

(OP)
Hi guys. Just wondering if any of you know what the B31 Code (31.4 in this case) implications are for roping a pipeline cross-country. This is the practice of laying the line down, either on grade or on supports, and forcing it to bend into very large radius bends to conform to the local topography, sort of like snaking a hose around your yard only it's done with steel pipe. This saves bends as well as trimmed or mitered buttweld fittings and thus saves welds.

I have an 8" XH CL900 X52 water pipeline and owner wants to minimize bends (either shop or field) and welds by roping the pipe. Any help, opinions, or experience would be very much appreciated.

Thank you!!
Pete

RE: B31.X Code Implications of "Roping"

Errr, not quite sure what you mean by "implications", but see how this goes.

What you are referring to is elastic bending, i.e. stresses that result in less than the SMYS of the pipe.

The way it impacts the design is in the calculation for equivalent stress and calculation of longitudinal stress in 402.6.1, by use of the bending stress and section modulus.

Note that sometimes it is the +ve stress son the outside of the bend which results in max stress, sometimes it is the compressive stress on the inside of the bend and you need to calculate both.

Then if the stress passes the code check for your particular radius of bending then it's all good.

However it is quite easy to end up with thicker pipe due to a relatively low elastic radius and hence add costs this way.

In practice elastic bending in the vertical sense is relatively easy to undertake and measure to make sure you're not exceeding you calculated minimum bending radius. This minimum bending radius can be surprisingly high if your wall thickness is minimized for hoop stress alone. If you have a lot of crossings then don't forget to allow for the additional excavation costs required to gently slope your pipeline down and back up again. There's no such thing as a free lunch.

Side bends though can be much harder as you need to first build the pipe straight and then try to lay it in the trench where it is then hard up on one side of the trench, unless you've got a really gentle bend.

Personally I can't see the advantage of not using field bends - its the same number of welds as you use a single length of pipe and it makes construction a lot easier.

Also if you ever want or need to cut out a length to repair it, the residual stresses in the pipe will come back to pay you back big time.


a bend of up to say 5 or maybe even 10 degrees every couple of kms - I could understand that, but more than that and I wouldn't.

It is all dependant on location, angle and radius of the bends and quality of the construction.

Hope this helps.

LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to 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! Already a Member? Login


Resources

White Paper - Strategies to Secure Connected Cars with Firewalls
White-hat hackers have demonstrated gaining remote access to dashboard functions and transmissions of connected vehicles. That makes a firewall a vital component of a multilayered approach to vehicle security as well as overall vehicle safety and reliability. Learn strategies to secure with firewalls. Download Now
White Paper - Model Based Engineering for Wire Harness Manufacturing
As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency. Download Now
White Paper - What is Generative Design and Why Do You Need It?
Engineers are being asked to produce more sophisticated designs under a perfect storm of complexity, cost, and change management pressures. Generative design empowers automotive design teams to navigate this storm by employing automation, data re-use and synchronization, and framing design in the context of a full vehicle platform. Download Now
eBook - Simulation-Driven Design with SOLIDWORKS
Simulation-driven design can reduce the time and cost of product development. In this engineering.com eBook, we’ll explore how SOLIDWORKS users can access simulation-driven design through the SOLIDWORKS Simulation suite of analysis tools. Download Now

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