Work with the Target Structure P/S Field

The Target Structure P/S field is a system-generated field available in the CPDM Test Point Inspection grid. The field is gray to indicate its contents are system-generated. Target Structure P/S is used by PCS to calculate a target reading with a minimum pipe-to-soil (P/S) for meeting criteria. The target reading is calculated based on your selected protection criterion and information in other fields.

The following table describes how Target Structure P/S is calculated for each protection criterion. Each protection criterion identifies fields required for calculating Target Structure P/S. Equations with pipe brackets ( | ) represent absolute values.

Calculating Target Structure P/S

Protection Criterion

Target Structure P/S Calculation

.85 On (default)

–0.850 V

.85 IRF

–0.850 – | Structure P/S – Structure IRF |

Example: –0.850 – | –1.200 – –0.800 | = –1.250

Note: The value in the field User IR Correction (if any) is used instead of the | Structure P/S – Structure IRF | equation.

100 mV

Native P/S – 0.100 – | Structure P/S – Structure IRF |

Example: –0.550 – 0.100 – | –1.200 – –0.800 | = –1.050

Note: The fields Native P/S and Native Date can be included with any survey regardless of how old. PCS always finds the most recent native reading and date, and the most recent pair of structure "on/off" readings (Structure P/S and Structure IRF). This means if the current-year survey includes only "on" readings, PCS uses the last "on/off" reading and native date. This is the case until a new "on/off" reading is taken.

300 mV

This is no longer recognized by AMP RP0169 or DOT regulations.

Ref Read

Add the field Test Point Reference P/S in the grid when using "Ref Read" (reference reading) protection criterion.

Ag/AgCl

Functions the same as ".85 On" but uses –0.800V instead. Use this protection criterion for off-shore (saltwater) or tank "on" readings when using silver/silver chloride half cell.
Custom On

Functions the same as ".85 On" but uses a custom value instead of -0.850.

The user-defined custom value is input under the Criteria pane of the Options window.

Custom IRF

User-defined Custom Value – | Structure P/S – Structure IRF |

Functions the same as ".85 IRF" but uses a custom value instead of -0.850. The user-defined custom value is input under the Criteria pane of the Options window.

Custom mV Shift

Native P/S – User-defined Custom Value – | Structure P/S – Structure IRF |

Functions the same as "100 mV" but uses a custom value instead of 0.100. The user-defined custom value is input under the Criteria pane of the Options window.

The field Target Structure IRF is used for a facility to meet criteria and the calculated minimum value for the Structure IRF field.

.85 On criteria

Calculation: Target Structure IRF = Null

.85 IRF (off) and 100mV criteria

Structure IRF can be compared to Target Structure IRF to determine if the inspection is in compliance. If Structure IRF is more negative than Target Structure IRF, the test point is in compliance.

  • Calculation for .85 IRF Criteria: Target Structure IRF = -.85.

    Target Structure P/S is calculated for an inspection that has a Structure IRF.

  • Calculation for 100mV Criteria: Target Structure IRF = Native P/S - 0.1. Native Date must be added in the grid.

    Target Structure IRF is calculated for an inspection that has a Structure IRF.

    Native P/S = Most recent Native P/S before the date of the Structure P/S and Structure IRF.

.85 On

Calculation: Target Structure IRF = Null

300 mV

Calculation: Target Structure IRF = Null

Ref Read

Calculation: Structure P/S = Null

The default setting for Target Structure P/S is -0.850.

Complete the following steps to change the setting:

  1. Open the Test Point Inspection grid.

  2. Select the field Test Point Protection Criteria for a test point in the grid. Click the down arrow and select a protection criterion in the selection list. Repeat this step for other test points as needed.

  3. Set up other fields used to calculate Target Structure P/S. Based on how your data entry grids are arranged, fields may be in the Test Point Information or Inspection grid.