I have few questions on PVELITE 2016 regarding the FFS per API-579-1.

1- Why options are dead in PVELITE for Part 5 and Part 6 assessment? Only Part 4 option is live.

2- Why PVELITE does not accept the thickness reading more than nominal thickness? I entered many time point thickness readings for Level 1 general metal loss assessment. Out of 15 values, 10 values are more than nominal thickness but PVELITE is not accepting these values. When I put these values equal to nominal thickness, PVELITE accepts it.

3- When either Level 1 or Level 2 assessment is performed (for Part 4), corrosion rate should be based on minimum thickness or average thickness? PVELITE takes corrosion rate as an input.

Hello, JavedNasir!

In the 2016 version of PV Elite, we had not yet implemented Parts 5 and 6 yet, although we provided a preview of what was to come. You can use these features in the 2017 edition of PV Elite which has also been updated to the 2016 edition of API 579/ASME FFS-1. Please also be sure to install the service pack.

Nominal thickness is akin to the as-built thickness of the vessel in the fitness for service module. We want to be sure you're not accidentally adding extra thickness to the vessel. To correct for this in your model, I would first put in the greatest measured thickness as your nominal, or as-built thickness, as a starting point, then enter the thickness readings.

The design corrosion rate is only used in the fitness for service analysis if none of your measured thicknesses have breached that initial corrosion allowance (CA). In that case, no analysis is necessary and we provide a note stating that. This design corrosion condition can be found near the beginning of Part 4. Future corrosion rate (FCA) or (FCAml) is taken from the point of where your measured thicknesses are now. FCA is the corrosion rate away from the flaw, while FCAml is the corrosion rate at the flaw. This the term that is also used in Part 4, General Corrosion, since you're flaw is over the entire element.

If you use a zero FCAml, you're basically asking the question, where do we stand right now? You can also calculate this value if you have a corrosion rate and a given time frame. A third way to approach this is to iterate over it till things start to fail in the analysis, which will give you your maximum FCA.

Thank you for using PV Elite! Please let me know if you have any additional questions. We also have some webinars and workshops on this you can access here: http://www.coade.com/products/pv-elite/PV%20Elite%20Webinars.

Dear Kristin,

Thanks for explaining.

I was asking the corrosion rate determination method for the sake of performing remaining life assessment as per 4.5.1.1. As you know PVELITE does not ask for how long the equipment has been in service, so without service life PVELITE cannot calculate corrosion rate, so PVELITE requires user to enter corrosion rate.

Option No. 1- Corrosion Rate = (tnom- tam)/No of years in service
Option No. 2 - Corrosion Rate = (tnom - tmm)/No of years in service

Inspection has been performed first time, hence no previous tam is available. Which option (1 or 2) is correct to calculate Crate and to enter into PVELITE. Option 1 uses tam and option no. 2 uses tmm.
We have Point thickness readings data with us.