MAWP or MFH Approach

Select whether to manually enter the maximum allowable working pressure (MAWP) or have the program calculate it. Additional inputs will be required to calculate the MAWP. For atmospheric storage tanks maximum fill height (MFH) will be used in place of MAWP. This input only appears for assessments to the API-579 code.

Corrosion and Pitting Damage are acting on the same side?

See figure for reference and select "Y" or "N"

Basis for Dimensions

Select whether to use nominal or corroded dimensions as the basis for data entry. Nominal dimensions are the original design dimensions; this option should be selected if input is based on original design documentation. Corroded dimensions are the dimensions in the current, corroded state; this option should be selected if input is based on recent measurements.

Component Shape

Select geometry based on the type and shape of the component.

Location of Metal Loss

Select whether corrosion is located on the inside or outside. The assessment is not valid when corrosion is present on both the inside and outside diameter.

Maximum Allowable Working Pressure, MAWP

Enter the maximum allowable working pressure (MAWP) of the component. The MAWP should account for any prior uniform metal loss (LOSS) and future corrosion allowance (FCA). This input will appear only for pressurized components assessed to the API-579 code.

Maximum Fill Height, MFH

Enter the maximum fill height (MFH) of the component. The MFH should account for any prior uniform metal loss (LOSS) and future corrosion allowance (FCA). This input will appear only for atmospheric storage tanks assessed to the API-579 code

Nominal Thickness

Enter the original component thickness in requested units. This input appears if Nominal Dimensions basis and User Entered MAWP/MFH is selected.

Prior Uniform Metal Loss Remote From Damaged Region, LOSS

Enter the amount of uniform metal loss away from the local metal loss location at the time of the assessment.

Uniform Corroded Thickness Away from Pits, trd

Enter current thickness including corrosion in requested units. This input appears if Corroded Dimensions basis and User Entered MAWP/MFH is selected.

Future Corrosion Allowance to Account for Uniform Metal Loss, FCA

Enter the future corrosion in the component in requested units. This input appears if User Entered MAWP/MFH is selected.

Future Corrosion Allowance Local to Region of Pitting, FCALOCAL

Enter value in requested units. 

Max Pit Depth, wmax

Enter the maximum pit depth measured in the pitted section to be analyzed, in requested units.

Max pit diameter

Enter the maximum pit diameter so that the software can check whether Equation 6.10 is satisfied. If it is not satisfied, then the pit should be evaluated as a local thin area.

Allowable Remaining Strength Factor, RSFa

Enter the allowable remaining strength factor for the component. The recommended value for RSFa per API-579 Part 2 paragraph 2.4.2.2.d is 0.9. Refer to API-579 Annex 2F for guidance on establishing alternative values for RSFa.

Upload Image of Pitting (optional)

For reporting purposes, the software has the capability to upload a surface damage or rubbings image of the pitted component. For best graphical results, the image size should be limited to 200 x 200 pixels. 

Click on Browse button to select an image and then Upload to include the image in the assessment dataset.

Selected API 579 Pitting Chart Figure

Compare the surface damage from the image or rubbings to the standard pit charts [1] Figures 6.3 through 6.10 or "Exceed 6.10" where the pitting damage is more extensive than 6.10. The pit chart will display on the screen.

Next

Click Next to return results of the Level 1 Pitting Assessment