×
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

Round Tube / Pipe Moment Splice

Round Tube / Pipe Moment Splice

Round Tube / Pipe Moment Splice

(OP)
I'm currently doing research for a project that will require several moment splice connections for round steel tube / pipe sections.  Each splice will also contain a reduction in the diameter of the next pipe section.  The project is a tall spire (200'+) and I am proposing to design it similarly to a steel stack vessel.  I've already found a good reference (ANSI/ASME STS-1-2006), but have yet to order.

Anticipating that this reference does not include the design of the connection I've mentioned, I was hoping to see if any of you knew of any good references.  I have conceptually laid out the connection (see attached file) and have some ideas on how to analyze, but am looking for some back up material to make sure I'm covering all bases.

 

RE: Round Tube / Pipe Moment Splice

The drawing looks like you are planning on using bolted connections. Assuming that each pipe is long and has a relatively small diameter, the bolt head (or the nut) inside the larger pipe is not accessible for tightening during assembly.

If this is true, perhaps tapped holes, nuts welded inside, etc. could be a solution.

www.SlideRuleEra.net idea

www.VacuumTubeEra.net r2d2

RE: Round Tube / Pipe Moment Splice

(OP)
Actually, the diameter is large enough to allow an internal ladder for maintenance at the top of the stack.  So internal bolting of the flange is an option.  Each section is 40' long (for shipping) and diameters range from 72" to 42".  Welded nuts would be a good idea though...

RE: Round Tube / Pipe Moment Splice

There is a body of opinion that high strength nuts should not be welded, even for this purpose.  There is a current thread around somewhere about that.

Is the spire to be ground mounted or on a building?  If on a building, I would research oscillation initiated failures.  I can't really give you any details, other than to say I have read about problems with antennas, spires, etc. on tall buildings.

The welding of the flanges to the pipe sections should be complete penetration, which would probably best be done from outside with backing bars inside.

I have seen similar spires made tapered rather than stepped.  Don't know how they do it, but would avoid stress concentrations.

RE: Round Tube / Pipe Moment Splice

What about a round plate with smaller pipe diameter inserts (to be used as backing for the welding) that are welded to the plate...  These inserts could be long enough to have holes for temporary thru-bolts for the in field welding alignment of the pieces.   

Mike McCann
MMC Engineering

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