Tube Buckling
Tube Buckling
(OP)
Hello all and thanks in advance here,
I've got a Shell & Tube Heat exchanger with 4 3/4" thick tubesheets. (Stationary and Floating)
It's a Tema type AES exchanger -- 61" I.D. shell and channel with (2544) 3/4" o.d. Tubes on a 1" 45 degr. rotated sq. pitch.
It's all carbon steel, SA-516-70N except for the 410 S.Stl. Baffles. The tubes are welded SA-214 c.steel, Roller expanded only into the thubesheet.
It has a 5/16" corrosion allowance on the tubeside and runs at 308 psi @ 650 Degrees F. on the shellside and 308 psig @ 650 deg. F. on the tubeside.
My problem is the tubes are overstressed and I have no idea what are where to beef this thing up to eliminate the problem.
I apologize in advance for the length post, but all help is appreciate.
JW
I've got a Shell & Tube Heat exchanger with 4 3/4" thick tubesheets. (Stationary and Floating)
It's a Tema type AES exchanger -- 61" I.D. shell and channel with (2544) 3/4" o.d. Tubes on a 1" 45 degr. rotated sq. pitch.
It's all carbon steel, SA-516-70N except for the 410 S.Stl. Baffles. The tubes are welded SA-214 c.steel, Roller expanded only into the thubesheet.
It has a 5/16" corrosion allowance on the tubeside and runs at 308 psi @ 650 Degrees F. on the shellside and 308 psig @ 650 deg. F. on the tubeside.
My problem is the tubes are overstressed and I have no idea what are where to beef this thing up to eliminate the problem.
I apologize in advance for the length post, but all help is appreciate.
JW





RE: Tube Buckling
RE: Tube Buckling
RE: Tube Buckling
The exchanger service is " DE-ETHANIZER REBOILER"
The MAWP (shellside) is 308 psi @ 650 with a -20 MDMT @ 308 psi.
The MAWP (tubeside) is 190 psi @ 650 with a -20 MDMT @ 190 psi.
RE: Tube Buckling
Is the unit clean? Do operating conditions cycle a lot?
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P.E. Metallurgy, Plymouth Tube
RE: Tube Buckling
Tube buckling could be occuring on the heating medium side if steam condensate has some level on the shellside for example on a horizontal kettle. Give us a process description and process control details else you'll have many of us stabbing in the dark.
RE: Tube Buckling
Or it does not float enough, if the unit is rapidly heated the tubes may expand enough to buckle before the head moves enough to relieve the stress.
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P.E. Metallurgy, Plymouth Tube
RE: Tube Buckling
Another option would be to switch the baffle arrangement to a "No Tubes In Windows" design since NTIW baffles allow for intermediary support baffles, so you can dramatically reduce the unsupported tube length.
Both of these will help prevent tube buckling.
-Christine.