Vessel Cladding Thickness

[danjo]

Does anybody have any idea how to determine the required thickness of a vessel cladding? What I have is a CS vessel to be cladded with a CRA. So is there a standard somewhere that will let you know what the minimum cladding thickness will be required. This cladding is only for corrosion protection so its not intergal bonded that yo can consider in determining total vessel wall thicknes for pressure containment. This in a ASME VIII vessel.

Thanks.

 

[metengr]

The designer specifies the cladding material and thickness based on environment and reduced cost. Typically, cladding thickness is 1/8" nominal; I have seen some at 0.080" and others at 0.140".

 

[metengr]

You might also want to review ASME Section VIII, Div 1 Nonmandatory Appendix E; Suggested Good Practice Regarding Corrosion Allowance.

 

[SJones]

CRAs do suffer thinning in a lot of environments. If you look at Craig's NiDI paper, he quotes an acceptable rate of 0.05 mm/year in typical oilfield environments. So, that would give you a starter for 10 using the desired lifetime of the vessel. Then you will have to consider the method of cladding. Weld overlay may require two layers to give an acceptable dilution - so the thickness would be governed by that criterion. You would also have to look at fabrication details and tolerances to see whether there are risks of misalignment resulting in CRA butting against carbon steel and whether an increased CRA thickness could compensate. I'm sure there's a few other factors, not least economics, to consider.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/