Use of Corrosion allowance and Mill tolerence in Caesar-II

Dear All,

I have stupid doubt...!

In Caesar-II, why we mention corrosion allowance and mill tolerence (Per ASME B31.3)??

We already consider corrosion allowance and mill tolerence in thickness calculation per ASME B31.3.

Please explain, how it will affect on stress output??

Please reply as early as you can.

Thanks in advance for response.

Regards,
GSP

When you run the minimum wall thickness calculation, you end up with a value, that is increased for corrosion, then increased again for mill tolerance, and finally rounded up to the next commercial pipe size that you can purchase. This is the thickness you enter as an input value in c2 for the thickness of your pipe.

Most Piping Codes suggest that a flexibility analysis (i.e. the analysis that c2 performs) be done using the nominal (input) wall thickness. Certain Codes specifically state that certain load cases should be corroded or have mill tolerance deducted from the section modulus when making the stress calculation.

You referenced B31.3: this Code does not address mill tolerance in the flexibility analysis, and it corrodes the Sustained and Occasional load cases only.

Thankyou very much for your quick respose.

Regards,
GSP