Piping Inspection – Much More Than Thickness Monitoring

Process Piping: A High Working Load

Process units are filled with process piping, the main purpose of which is to transport fluids from one vessel to another. If you count all assets and consider each process pipe as one, you would find that process piping significantly outnumbers other assets, as illustrated in Figure 1, developed from a real 130 KBPD CDU. And this is only considering process piping >2” NPS. 

Based on this figure, one may think that most of field inspection’s man hours would be focused in piping systems. Thickness measurement during turnarounds can be an exhausting activity and require a dedicated crew. Over the last 30 years, thickness measuring devices have been developed and utilized for inspection activities, and some strict thickness measurement methodologies have been developed in order to help owner-users ensure that each reading is of sufficient quality and traceability to guarantee repeatability. Looping/circuiting methodologies have been developed in order to group piping with similar service (and similar damage) and select representative assets for inspection activities. But piping inspection is much more than just taking thickness measurements.

The Piping Inspection Standard

API 570 was originally released in 1988 (30 years after API 510), to help ensure the safe operation of piping systems. The code covers “in-service inspection, rating, repair, and alteration procedures” to guide operators in developing condition monitoring programs. It requires inspection plans to be designed to assess changes in the condition of piping that could affect its mechanical integrity.