Tube expansion procedure

[abangbikerz]

We manufactured a removable u bend heat exchanger. For the expansion of the tube. We received a last minute info from our client that the tube weld joint cant be expanded. Which means the expansion starts few mm from the face of the tubesheet, and the first few mm(4~5mm approx) of the tube are unexpanded. Nobody in our organisation had ever heard such thing. Usually we just expand the whole length of the tubesheet thickness. I check the TEMA requirement and found no such thing. Did anybody here know any reference to relevant codes indicating this kind of requirement???

 

[SnTMan]

abangbikerz, at least one standard makes this requirement (API 660), and it is very common in buyer / owner specifications. The intent is to avoid cracking of the tube-ts weld by rolling it.

Did you test your rolled welds at all?

Regards,

Mike

 

[abangbikerz]

thanks sntman.

but our HE does not being contructed under api 660 requirement.
but what do you mean by ' test your rolled welds'??

 

[mechyp]

if ur HE as per ASME VIII-I

See UHX-11

ltx the expanded tube length in tube sheet fig UHX 11.1


yogesh

 

[SnTMan]

abangbikerz, not uncommon for tube welds to be penetrant tested after rolling, also possible to air-soap (bubble) test and sensitive leak test, such as helium, normally performed by pressurizing the shell side, leak checks made on the tubeside.

Regards,

Mike

 

[abangbikerz]

sntman we do make a DPT test after rolling the tube.

 

[SnTMan]

abangbikerz, if not detecting cracks you are probably OK, however I would revisit the practice for the future.

Regards,

Mike

 

[chicopee]

Seal welding of tube ends is no big deal on expanded tube ends as long as the welder knows what he/she is doing.

 

[chicopee]

I should further mentioned that when tubes are expanded in the tube sheets, the tube ends can be then either flared or beaded to which you seal weld. I think that your customer meant seal welding instead of having strength welds.