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heat exchanger tube expansion

heat exchanger tube expansion

heat exchanger tube expansion

(OP)
what is really the point to expand the tube after welding.

is it has something to do with the liquid flow efficiency or is it because to close the gap between the tube and tubesheet on the inside??

RE: heat exchanger tube expansion

It is to establish the mechanical strength of the tube-to-tubesheet joint. Depends on your weld too. If your weld is a stength weld, the roll may not be needed for strength, but for prevention of penetration of process fluid between the tube outer wall and tubesheet (especially if crevice corrosion potential exists.)

I once saw a very high pressure Hx where they forgot to roll one entire row of one half of the TS and the weld was a seal weld only but the Hx survived for over 20 years and when it failed it failed for reasons other than the forgotten row. Now, on the other hand, would I on that basis not roll - not for a minute.

rmw

RE: heat exchanger tube expansion

(OP)
thanks rmw.

but i believe that most of the tube to tubesheet weld is a strength weld. where tube is protruded about 2mm from the tubesheet and welded with gtaw process. tubesheet hole is also bevelled. how is tube to tubesheet seal weld configuration??

RE: heat exchanger tube expansion

In a seal weld the tube may be flush or it may project, there is no filler metal, and the penetration is shallow.
The other reason to roll is that the span for vibration purposes is shortened.
I have seen tubes fracture in HX with thick tube sheets when the tubes vibrate and bend when hitting the back face of the tubesheet.

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Plymouth Tube

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