Snapped tube expander shaft

[marty007]

Hello,

During fabrication of a shell/tube heat exchanger, we have had the shaft of a tube expander break while rolling one of the tube/tubesheet joints. It's now jammed in there, and I'm wondering if anyone has any experience or ideas on how to remove the broken portion without damaging the rest of the tubesheet.

Some details:
Tube size: 3/4" OD x 14GA C.S.
Tubesheet thickness: 2-1/2" C.S.
Tube/tubesheet joint: 2 x 1/8" wide x 1/64" deep grooves
Tube expander shaft material: tool steel
Tube layout: 1" pitch, square pattern.

The problem I see is that the tubes are partially expanded already, so pulling the tube may be impossible. Drilling it out could be very difficult since the expander shaft is tool steel.

Any ideas?

Thank you,
Marty

 

[fegenbush]

You don't say the length of the tubes, but I would drive/knock the expander out with a long rod from the other end. Then you will have the expander head that you can put on a bench and repair. If the tube bundle is a U-tube design, obviously this will not work. If I am misunderstanding the problem, a picture may be in order.

 

[marty007]

Tubes are 16' long, straight tubes (no u-bends).

Our shop already tried banging them out from the opposite side with a long piece of bar stock, no luck.

I think you have the right idea. This is the first time I've seen this happen, not an easy fix.

I'm starting to hope that maybe the client can do with one less tube... just plug the one tube.

Thanks anyways,
Marty