ILI dig verification is the field verification of an anomaly or feature reported by an in-line inspection tool, typically through excavation, direct examination, and comparison of field measurements with the original ILI call. The dig exposes enough of the pipe and surrounding condition for qualified personnel to locate the reported feature, examine it directly and record measurements that can be compared with the ILI call. The purpose is not merely to confirm that an ILI response exists. It is to determine what condition is actually present, establish its physical location and dimensions, and evaluate how the field findings compare with the reported ILI data.
Why an ILI feature is verified directly
An ILI system reports a feature through a tool response and an interpreted location or geometry. Tool performance, operating conditions, odometer drift, reference assumptions, coating, deposits, feature interaction and the limits of the inspection technology can all affect the reported result. Direct examination provides an independent field record of the pipe condition and creates the evidence needed to refine location, dimensions and classification.
Field verification helps determine whether the reported response corresponds to corrosion, cracking, deformation, weld geometry, seam-related features, coating or surface conditions, or another physical condition. The field team may find general corrosion, a pit, crack-like damage, a dent, a seam-related feature, a weld-related indication, a coating condition, or no corresponding reportable condition within the examination area. The difference is important because the follow-up method and assessment basis depend on the actual condition.
What is recorded at the dig
A useful dig record connects the ILI call to physical references and repeatable measurements. The exact form depends on the operator's procedure and the inspection scope, but the record commonly includes:
- Pipeline, segment, direction of travel, tool run and ILI reference or feature identifier.
- Stationing, odometer or wheel-count information, girth-weld references, GPS where collected and the correlation method used to reconcile them.
- Pipe outside diameter, nominal wall, grade or material information and coating or surface condition.
- Feature type, clock position, axial and circumferential extent, maximum depth, minimum wall thickness and the UT grid or profile spacing.
- Photos of the exposed pipe, feature, reference welds, coating, excavation and any repair condition.
- Limitations, inaccessible areas, field conditions, instrument details, calibration information and reviewer or inspector notes.
From field measurement to anomaly assessment
After the feature is examined, the field measurements are compared with the ILI dimensions. A difference does not automatically mean that one dataset is wrong. The team should document the units, datum, location reference, measurement uncertainty, surface preparation and whether the ILI feature and field feature are being compared at the same boundaries.
The verified dimensions and field observations can then support remaining-strength assessment, interaction review, anomaly classification, repair planning, monitoring, or other integrity decisions under the operator's procedures. Where corrosion-caused metal loss is confirmed and the required inputs are available, validated field dimensions may be used in B31G, Modified B31G, RSTRENG, or another applicable remaining-strength assessment method in accordance with the governing procedure. The Pipeline Integrity workflow keeps ILI calls, dig observations, UT grids, calculated results, repair documentation and report pages connected for review. The software preserves and organizes the inspection record; qualified inspection and integrity personnel remain responsible for technical interpretation and final disposition.
Documenting a no-find or mismatch
A no-find or materially different result is still a useful outcome. Record the search area, reference features, excavation limits, inspection method and reasons the original call could not be confirmed. Avoid silently replacing the ILI data. Preserve the original call and add the field conclusion so later reviewers can understand the decision path.
A no-find does not automatically invalidate the ILI call. Datum error, odometer tolerance, feature interaction, incomplete exposure, reference-feature mismatch, or examination coverage should be considered before concluding that the reported feature is absent.
Questions inspectors ask
Is ILI dig verification the same as an ILI re-run?
No. It is a direct field examination of a reported location, normally using visual examination and suitable NDE such as UT or profile measurements.
What makes the location record defensible?
Use more than one reference where practical: stationing, girth welds with the measured distance from the reference weld, odometer or wheel count, GPS where collected and clear photos or sketches. Weld references and measured distances from them are among the most important correlation anchors.
Does a verified feature automatically require repair?
No. Verification supplies evidence for assessment and disposition. Repair, monitoring or continued operation remains an engineering and operator decision under the applicable procedure.