EXPANDED TUBE WALL REDUCTION FOR HEAT EXCHANGER 1

[slhandle]

What is the recommended tube wall reduction when 1" O.D. 14 BWG MIN or 12 BWG MIN admiralty tubes are expanded in the naval brass tubesheet of a shell and tube heat exchanger?

 

[metengr]

What are your design conditions for this heat exchanger?

 

[slhandle]

I have two heat exchangers:
Tube side 75 psig @ 250 deg F for both exchangers.
Shell side 175 psig @ 250 deg F for the exchanger with 14 BWG MIN tubes; and Shell side 625 psig @ 250 deg F for the exchanger with 12 BWG MIN tubes.

 

[metengr]

Typically, I have seen tube wall reductions of 7-9% for brass tubing in similar tubesheets. I checked an HEI Power Plant Heat Exchanger Standard and there is no mention of wall reduction, other than tubes should be expanded into the tubesheet to within 1/8" of the shell side face.

I would strongly suggest that you fabricate a small mock-up of the tubesheet and roll the brass tubes into the tubesheet for subsequent pull out tests. The operating temperature is low enough that tests conducted at room temperature will provide you with comparable pull out strength values to optimize your design.

 

[unclesyd]

Like all the makers of tube rolling equipment these people have guides. As stated above a few test tubes coupled with a good internal mike goes a long way in setting the tool. There is lot more to expanding tubes in tubesheets than the just the tube wall reduction. I would get you tool suppliers catalogue or manual and line up every variable they mention. I was just recently appraised of a blotched tube rolling job due to the fabricator changing the roller lubricant, so get everything in order.

Here is their catalogue that has some general information in the lead in.

http://www.equipmentgroup.com/cat_pdfs/catalog.pdf