ASME B3IG Maximum Allowable Longitudinal Extent of Corrosion

The depth of a corrosion pit may be expressed as a percent of nominal wall thickness of pipe by:

where
𝑑 − measured maximum depth of the corroded area(in)
𝑡 − nominal wall thickness of pipe,inches.
Additional wall thickness required for concurrent external loads shall not be included in the calculation.
A contiguous corroded area having a maximum depth of more than 10% but less than 80 % of the nominal wall thickness of the pipe should not extend along the longitudinal axis of the pipe for a distance greater than that calculated from:

where
𝐿 − maximum allowable longitudinal extent of the corroded area(in)
𝐷 − nominal outside diameter of the pipe(in)
𝑡 − nominal wall thickness of pipe,inches.
B may not exceed the value 4. If the corrosion depth is between 10% and 80%, use B = 4.0 in Equation.

Input Parameters

1. Select the ANSI B31G-1991 Maximum Allowable Longitudinal Extent of Corrosion application from the Pipeline Corrosion list.
2. Enter Case Name, Location, Date and any necessary notes.
3. Fill out all required fields.
4. Make sure the values you are inputting are in the correct units.
5. Click the CALCULATE button.

• Maximum Depth of Corroded Area(in)
• Pipe Outside Diameter(in)
• Nominal Pipe Wall Thickness(in).

   

Outputs/Reports

1. View the results.
2. If an input parameter needs to be edited be sure to hit the CALCULATE button after the change.
3. To SAVE, fill out all required case details then click the SAVE button.
4. To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
5. To generate a REPORT, click the REPORT button.
6. The user may export the Case/Report by clicking the Export to Excel/PowerPoint icon.
7. To delete a case, click the DELETE icon near the top of the widget.

• Maximum Allowable Longitudinal Extent of Corrosion(in)

Related Links