Minimum thickness of vessel to maintain ovality

[Sachin Pawar]

Hi All,

How do we select thickness of a large dia low pressure vessel to maintain ovality in shop fabrication, transport, erection & operation. We have a column with structured packing having stringent tolerance requirement and thickness required for pressure is very low.

There is formula in many specs : D/1000 + 2.5 + Corrosion Allowance.

Does this help?

Thanks,
Sachin

 

[weldstan]

What is the diameter and material? Shops often use internal spiders to maintain ovality during construction and transport. For most carbon steel vessels a general rule had been to have a minimum nominal thickness of 3/8".

 

[MJCronin]

Sach,

Some questions:

- You state "maintain ovality",is this what you mean ? .... Do you want to maintain or prevent an oval shape of your fabrication ?

- "Structured packing" implies a distillation or separation process that will have some design pressure above atmospheric ... What is it ?

- A distillation column implies some kind of closure on your device ? Do you have vessel heads ? ... What are the details ?

- How is your vessel supported ?

- Can you post more operating and material selection details ? What vessel design Code are you trying to meet ?

- Is this your first involvement with pressure vessel design ?

- Can you post vessel design drawings, or will your MBA boss prevent you from doing this ?

MJCronin
Sr. Process Engineer

 

[JStephen]

Roark's Formulas for Stress and Strain includes some load cases for circular rings which can be applied in some cases, either to a stiffener section, or to a unit length of shell, to determine deflections if the loading matches one of the load cases given.
If any external pressure is present, it may govern design.
For large thin-wall atmospheric tanks, shell buckling due to wind or seismic action is a design condition that may govern thickness.