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During ultrasonic wall-measurement inspection, trapped air or gas pockets can interrupt the acoustic path between the sensors and the pipe wall.

When this happens, the tool may record weak, or missing echoes—even though it continues travelling normally.

This risk is especially important near:

• High points and elevation changes
• Vertical or inclined pipeline sections
• Locations where filling or venting is incomplete
• Areas affected by unstable flow or residual gas

In Some Cases, the Quantity of Liquied available in the pumping source are not enough to fully surrond the sensors all over the pipeline during tool run,

Before running a UT ILI tool, engineers should review the pipeline elevation profile, confirm effective venting, assess the filling procedure, maintain suitable pressure and flow conditions and check the quantity of Liquied Available in the pumping station to ensure that this quantity can at least fill the pipeline 1.5 Times.

Cleaning and conditioning runs can also help identify operational restrictions before the inspection tool is launched.

If extensive echo loss occurs, the team must determine whether it represents a localized sensor issue, a coupling problem, or an inspection-wide data-quality limitation. Tool passage alone does not prove inspection success—the required wall coverage and usable data must also be achieved.

How does your team manage trapped-air risks before a liquid-coupled UT inspection?

#UltrasonicInspection #InlineInspection #PipelinePigging #PipelineIntegrity #ILI