Understanding NASSCO Pipe Rating System | 360 Pipes

PACP Quick Rating

Pipe Ratings

Pipes and structures are graded based on the number and severity of defects observed. Ratings are found on the Condition Ratings tab.

Structural and O&M Ratings

Structural and O&M Ratings are calculated by:

1. Grouping the Observations by Type and Grade.
2. Multiplying the Grade by the # of Occurrences.
3. Adding the results of Step 2.

Total Ratings

Total Ratings are calculated by:

• Adding the results of the Structural and O&M Ratings.

Rating Indexes

A Rating Index is the average grade of a type of defect found in the inspection. These calculations are based on the pipe ratings and on the number of occurrences. The formulas for these indexes are:

• Rating Index Structural = Total Structural Rating/Total Structural Occurrences
• Rating Index O&M = Total O&M Rating/Total O&M Occurrences
• Rating Index Total = Total Rating/Total Occurrences

Quick Ratings

Quick Ratings are codes that give users an overview of the worst defects observed during the inspection.

Structural and O&M Quick Ratings

These are calculated by:

1. Grouping the observations by Type and Grade.
2. Identifying the highest grade for a type of defect.
3. Identifying the number of occurrences of that grade.
4. Identifying the second highest grade for a type of defect.
5. Identifying the number of occurrences of that grade.
6. Forming the Quick Rating using the following syntax:

[Highest Grade for Type][# of Occurrences][Second Highest Grade for Type][# of Occurrences]

Total Quick Ratings

This is calculated by:

1. Grouping the observations by Type and Grade.
2. Identifying the highest grade of all defects.
3. Identifying the number of occurrences of that grade.
4. Identifying the second highest grade of all defects.
5. Identifying the number of occurrences of that grade.
6. Forming the Quick Rating using the following syntax:

   [Highest Grade][# of Occurrences][Second Highest Grade][# of Occurrences]

   Note: According to PACP/MACP, if the number of occurrences is greater than 9, the letters A-Z are used to represent additional occurrences in the Quick Ratings.