Inertial ILI Results Guide Repair And Risk-Based Mitigation Decisions

An intelligent inline inspection run including XYZ mapping provides valuable input in various assessment methodologies and the automated integration of the accurate pipeline centerline with its physical properties into a central pipeline integrity management software allows for a cost-effective and time-saving enhancement of the accuracy and reliability of the assessments results.

This article looks at the software-aided process of this automated geographical pipeline centerline creation as the basis for a High Consequence Area analysis and how it is finally utilized to provide the necessary input on immediate defect criticality prioritization and a risk-based mitigation strategy.

Given that the task was one of developing a risk-based mitigation strategy for 7,000 km of liquid pipelines, buried onshore as well as offshore, the project was one that required a huge amount of input data to allow for reliable conclusions.

Looking to all the available sources, inline inspection data is primarily considered as the solution on the identification of the current situation on a particular piece of pipeline. But a combined XYZ mapping run not only provides valuable information on the geographical location of individual anomalies, it also provides information on prioritizing those by their immediate potential environmental impact as well as giving the most necessary input on a future consequence assessment: the actual detailed pipeline route and its interaction with nature and human settlements.

For the project under consideration here, API 1160 is the identified and named code to guide the operator on pipeline integrity matters. Among the immediate defect assessment reference was made to the code to tackle with that data also the following matters:

• Defect Assessment: “Anomalies located in or near casings, near foreign pipeline crossings, areas with suspect cathodic protection, or high consequence areas should take precedence over other pipeline locations with similar indications.”
• Risk Assessment: “The consequence is estimated as a combination of variables in categories such as environmental receptors, population, business interruption, spill size, spill spread, product hazard.”

To support the responsible engineers in this process properly, a software solution was put in place that, among other capabilities, automatically integrates this data to update all related assessments performed in the various software modules provided. A generalized workflow is outlined in Figure 1.

XYZ Principles
XYZ Mapping has been developed for the identification of three-dimensional geographical pipeline coordinates by an inertial navigation unit. At the same time, the inner geometry of the pipeline is monitored simultaneously.

The survey results include information about the XYZ location of the pipeline, visualized by plan, elevation and distance views. Pipeline alignment, direction, horizontal and vertical bend orientations with respect to angle, radius, direction and location, are accurately measured, computed and reported. In addition, deformations such as dents, ovalities, wrinkles, etc. are also recorded. To get an indication on the setup of an XYZ Mapping Tool refer to Figure 2.

Figure 2: Setup of an XYZ Mapping Tool.