When re-rating a vessel for a higher pressure that has been service, and possibly has some corrosion, what thickness should be used: the minimum (determined by UT) or the original nominal less the corrosion allowance?

Hello waterguy

Using the minimum surveyed thickness is a conservative approach. However, there is an alternative. The publication: API 579 gives a procedure for surveying the thicknesses in a corroded region of the vessel wall, and then determining (from that survey), the future MAWP of the vessel, or the predicted life of the vessel.

I am not an expert on API 579, but PV Elite has the functionality to do an API 579 analysis. If I were you, I would do some research on API 579, and give it some consideration.

Thanks Ray,

That makes sense. I found it in the details section, but when i click on it nothing happens.

Ray,
Never mind.

Hello waaterguy

Don't give up yet. We do have an API 579 specialist in the Houston office. She knows much more than I. If you would like to know more, please let me know.