×
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

Heat Exchanger Fabrication Question?
2

Heat Exchanger Fabrication Question?

Heat Exchanger Fabrication Question?

(OP)
In a dilemma about exactly how tubes are stuffed in a multi baffle plate heat exchanger.  The half plate baffles are already stitch welded on inside of exchanger pipe.
 
With only a 1/64" clearance in holes for tubes I cannot fathom how one would insert a 35 ft tube thru the full length of a pipe with half baffle plates every 8 ft..
 
It seems like you would need a broom handle type wood stick aligned thru full length of pipe thru each baffle and then use it as a guide for the tube.
 
I don't know, have you had any experience around heat exchanger fabrication?

Appreciate your comments and advice,
Robert

RE: Heat Exchanger Fabrication Question?

I hope someone carefully aligned the baffles before stitching them into the shell.  If they did and they knew what they were doing, you should be alright.  They should have used round bars to align the support plates before welding

Are you planning to use guide 'bullets' in the tubes when you insert the tubes?

rmw

RE: Heat Exchanger Fabrication Question?

(OP)
Baffles would be perfectly aligned.  Can you expand on the guide bullets, are these plastic caps on the end of pipes and where might I purchase?

Thanks,

RE: Heat Exchanger Fabrication Question?

Tube guides distributed by the same companies that distribute rolling motors and expander tooling have a wide variety of options for tube guides.  It's usually a nylon brush attached to a tapered bullet to match your specific tube size.

Page 12 here:
http://www.elliott-tool.com/media/catalog/tube-installation.pdf

Or here:
http://www.tcwilson.com/heat_exchanger/accessories_tools/aluminum_tube_guide.php

Or here:
http://equipmentgroup.thomasnet.com/viewitems/tube-tool-accessories/tube-guide?

-TJ Orlowski

RE: Heat Exchanger Fabrication Question?

The tube guides would definitely be helpful, but I hope your tube wall is heavy enough that the tube isn't very "floppy", and your tube supports are pretty thick.  If your tubes are going to bow a little bit once you get about halfway (especially with 8 feet between supports [do you have ~4 or ~8 supports?]), I would not envy the guys who had to tube that unit.

-TJ Orlowski

RE: Heat Exchanger Fabrication Question?

qcrobert, a guide 'bullet' is a rounded end solid plug.  The plug is shaped like a pistol bullet, with an ogive.  Better bullet plugs are also tapered down thier length so the butt is larger than the diameter just behind the ogive.  Then a reduced diameter section is machined to fit into the ID of the tube being 'stabbed' into the bundle.  Reduced section should be at least 1-diameter long.

Do not be supprised if your baffles have to be cut loose.  The placement tolerance of baffles with 1/64" total clearance spaced several feet apart will be on the order of plus/minus 0.001".  Might even be less than .001".

RE: Heat Exchanger Fabrication Question?

(OP)
Thanks to all for enlightening me, I greatly appreciate it!

Duwe6, we will set baffle plates with laser as we have done in similar circumstances calling for tight tolerances.

RE: Heat Exchanger Fabrication Question?

Even with careful baffle alignment and the use of bullets in every tube, I have still seen tubes that gave fits in order to get them stabbed into the bundle.  Some Hx's are just that way.

Now that it seems that you have gotten the answers you were looking for, I have a question - purely curiosity.

How did this Hx question get put in a pipeline forum, especially with the quality of the sites heat exchanger forum?

rmw

RE: Heat Exchanger Fabrication Question?

normally one would try to build a tube bundle where the baffles are set out of the shell using tie rods to space the baffles. We try to stay away from fixed tube sheet bundles if at all possible.
We use a an H section turned on it;s side to hold the bundle while being fabricated.  you may have to use a guide bar of far end, nothing but a rounded bar.

rmw
The shell is a section of pipe.  

RE: Heat Exchanger Fabrication Question?

(OP)
rmw, to answer your question, "How did this Hx question get put in a pipeline forum, especially with the quality of the sites heat exchanger forum?"

I am sorry I did not see a Heat Exchanger forum here, only placed here because of Piping, Fluid Mechanics.

Even tho all have been very helpful here and have answered my questions could you please direct me to the Hx forum in case I have other related concerns.

Thank you,
Robert

RE: Heat Exchanger Fabrication Question?

(OP)
Never saw it before, then clicked on forums and sure enough there it is.

At 61, I just may need glasses.  ;)

Thank you,
Robert  

RE: Heat Exchanger Fabrication Question?

Robert,

I should loan you mine.  The don't do me much good anyway.

I was just curious about the forum choice, nothing else.  Since both fora involve fluids, a lot of us lurk in both places.

I never dealt with a lot of Hx's that were built in pipes.  Most that I ever had to deal with had heavy rolled plate shells that had to be pulled up on the bundle once the tubing was done.  But the method of aligning the baffles up prior to tubing is about the same in either case.  The baffles have to be well aligned or the tubing will be hell if you can do it at all.

rmw

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