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Minimum required thickness

Minimum required thickness

Minimum required thickness

Hi all,
I have some confusion on minimum required thickness of pressure vessel as per ug-16(b), which state that the minimum required thickness for unfired steam boiler and compressed air service or water service is 6 mm and 2.5 mm. But my vessel is used for curde oil service. so, which one I want to take as minimum required thickness as per code.

At the same time I have calculated the design thickness by using UG-27.

RE: Minimum required thickness

Refer UG-27. Let me tell you, thickness does not depend on what fluid you are using, its solely depends on your Pressure, MOC and dimension.

In case of UG-16(b), those fluids even if exposed to ambient will not have any ill effect, hence those are standard thickness provided by ASME.

Please correct me if i am wrong. Experts view will be highly appreciated.

RE: Minimum required thickness

If this is a pressure vessel under the scope of ASME Section VIII, Div 1, you use UG-27 to determine minimum shell and head thickness. UG-16 (b) simply states that the minimum thickness of shells or heads cannot be less than 1/4" (6mm).

RE: Minimum required thickness

For crude oil service you need to meet UG-16(b)that is minimum thickness to be 1.5mm + Corrosion allowance. In addition you need to perform UG-27 calculations based on design pressure and temperature

RE: Minimum required thickness

So are you saying that you would use a 1.5mm thk plate to fabricate a (say 914mm dia vessel) if the Corrosion allowance were 0mm and the thickness met the requirements of UG-27 for pressure and temperature? If so then please do not design any pressure vessels for the UK because what you are saying is dangerous. A vessel has to have sufficient thickness to be structurally sound as a minimum and 1.5mm thick plate is not structurally sound in many cases.

RE: Minimum required thickness

@ DSB123
Minimun wall thickness per AD Merblatter is 2 mm.


RE: Minimum required thickness

I know that!!!Doh!!! What I was indicating is that the minimum thickness is not just a figure it depends on the item being constructed. 2mm is the normal minimum thickness allowed but it depends on the structural strength and stability of the item as well not just pressure retention.

RE: Minimum required thickness

Dear DSB123
You need to consider all design loading conditions (pressure including internal and external, temperature and other loads) for minimum thickness determination. 1.5+CA is Code permitted minimum thickness provided other design rules are met

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