Pipe or thin walled vessel collapse calculations
Pipe or thin walled vessel collapse calculations
(OP)
I am interested in know what calculations are used to calculate the collapse stress of cylindrical thin walled tubes. E-funda indicated the hoop stress calculation and that it would yield a negative stress if external pressures are applied, but I am not sure this is correct. Does anyone have a different calculation?





RE: Pipe or thin walled vessel collapse calculations
Stress (per se) is not THE determining failure criteria for negative (external) pressure, buckling is the problem. This is a structural instability issue. The reference that you mention regarding hoop stress is VERY wrong.
The piping B31 Codes refer you to the ASME B&PV Code, paragraph UG-28 et. al. You will see rules in these paragraphs with table (the Code also gives you the data in the curves as a set of tables. You will notice that the B&PV Code rules are worked out so that you do not calculate stresses.
Best regards, John.
RE: Pipe or thin walled vessel collapse calculations
RE: Pipe or thin walled vessel collapse calculations
Please give me an e-mail address. I may have something to help you.
Regards, John
RE: Pipe or thin walled vessel collapse calculations
RE: Pipe or thin walled vessel collapse calculations
I tried the e-mail address twice and my message bounced both times. Can you give me a different e-mail address?
Regards, John.
RE: Pipe or thin walled vessel collapse calculations
Actually, I recieved both of your e-mails. I'll take a look at the spreadsheet and let you know how it works. Thanks again.
Daniel Der
RE: Pipe or thin walled vessel collapse calculations
The references that you have been given above might be fine, especially if your tubing is relatively stiff. If it is instead rather flexible and/or you are not actually so interested in the onset of collapse as you are interested in the obstruction of flow that is associated with the nearly complete collapse, then I suggest you read on:
Check some fluid mechanics and biomedical engineering journals. I know that Ascher Shapiro (emeritus professor - MIT) and some of his colleagues and students (S. Lichter is now both at Northwestern U.) published many papers on this subject beginning about 25 year ago (late 70's/ early 80's).
RE: Pipe or thin walled vessel collapse calculations