Acceptance Criteria for warped and twisted tubes of Air Cooled Exchanger

[leont]

Hi Everyone,
A visual inspection on tubes of an Air Cooled Heat exchanger revealed tubes were found warped, twisted and with sagging. The fluid is Reach Amine and tube-to-tubesheet joint is full expanded in double groove. Tube material is SA-170, OD 1" and BWG 14.
What is the acceptance criteria that will me out in order to keep this exchanger running safely and reliable?
Other than the tube to tubesheet joint (expanded and no seal weld), what could the immediate concern here?

Thank you in advance for any feedback on this matter and have a great day

 

[IRstuff]

Don't you think that warping, twisting, and sagging are red flag issues? Whatever happened to the tubes managed to mangle them; how do you know it won't happen again, and this time cause a rupture that could damage equipment and hurt workers?

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[leont]

IRstuff,
Firstly, thank you very much for your input.
I am really sorry if my wording was not clear enough.
I am not talking about a failed air cooled heat exchanger. What I am trying to say here is that my experience tells me there is an acceptance level of distortion on tubes of air cooled heat exchangers after being in continued service for a while, no mention anything related with upsets history, design and so forth. A closer inspection could tell me it is not necessary a red flag issue. I am fully aware of the risk and I know what I am dealing with. Therefore, what I am trying to get from the experienced mechanical engineers of this forum is quantitative or qualitative way how it'd be possible I can rise the flag based on finding clearly measurable in terms of offset from the longitudinal axis of the tube, location of the damage as of the fixed or floating header box, type of tube-tubesheet joint type and so forth.

Thanks

 

[IRstuff]

Seems to me that this should have been posted in forum391 or forum378

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[MikeHalloran]

No real expertise claimed here.

At this point, I'd be trying to calculate the strain associated with each warp/ twist/ sag/ dent/ whatever, and talking to the material supplier about the material's behavior at various strain levels in the particular environment.

I'd also be inspecting the maintenance/ purchasing records for hints about why similar units were repaired or replaced in the past, and at what time intervals they began to give trouble.

I'd especially be trying to gain the confidence of the oldest, crankiest, most inbred sumbitch maintenance mechanics in the plant; they probably know more than your own experience will ever tell you, until you become old and cranky, of course.



Mike Halloran
Pembroke Pines, FL, USA