Column 2

[arvindpandit]

Hi.......
Please let me know, why there is a thickness variation in column shell sections at same design condition. Like bottom shell course have more thickness and IInd may be same or less and so on.
Thnx in Advance.

Regards
Arvind Kumar

 

[sshep]

Consider the hydrostatic head of liquid, including potential full tower hydrotest in vertical position- pressure is higher at the bottom. Strength requirements are also higher at bottom to support column live and dead weight, and wind loads.

Best wishes,
Sshep

 

[25362]

In addition to Sshep's answer, sometimes column diameter changes; another factor could be differing corrosion allowances, depending on the column's service.

 

[arvindpandit]

Thanks for the reply.

But I saw a example in which bottom shell course had 25 mm thickness and IInd one had 16 mm and then the again on the 5th shell course the thickness was 25mm.
Why is it?

 

[MortenA]

Im not sure - but to me its would seem like a corrosion allowance issue. If the liquid medium is more agressive - or the hotter part of the collumn would accelerate corrosion - then more corrosion allowance is needed (ups saw that 25362 just posted that - but now i wont waste my typing..).

 

[racookpe1978]

And, then again, sometimes its cheaper, faster, and simpler to build that 5th stage identical to the 2nd or 3rd or 7th stage, rather then redesign and re-detail and reconfigure several stages into a "perfect" design.

repeating the same design multiple times IS cheaper than starting fresh every time.

 

[jte]

Arvind-

Not unusual to see lower shell courses being thicker, as mentioned by others due to hydrostatic head, CA issues, and wind and seismic.

What is a bit unusual is the circumstance you describe with the fifth course being thicker as well. So, let me ask you: Do the first and fifth courses have large nozzles in them? The thicker shell courses may be used for nozzle reinforcement, either area replacement, or for large piping loads.