Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers


X-Ray Inspection

Last updated: December 19, 2019

What Does X-Ray Inspection Mean?

An X-ray inspection is a non-destructive inspection method that uses radiography and is mainly used to identify CUI (corrosion under insulation).


Corrosionpedia Explains X-Ray Inspection

X-ray inspection is a real-time digital imaging system used to detect corrosion under insulation (CUI). Traditionally, to carry out such an inspection, sample areas would have to be identified within the circuit where insulation had to be removed and inspections carried out, which can be time-consuming, costly, and ineffective.

This method utilizes the principle of radiography. The principle of inspection is based on the absorption of gamma radiation in the tested material. A collimated beam of Gadolinium 153 isotopes is used as the source and the photons emitted from the source are received at a receiver. The source and detector are kept external to the pipe and positioned on opposite sides at a fixed distance apart. Gamma rays travel from the source through the pipe to the detector where the photons are received are counted. Proprietary software specially developed for this equipment converts the photon counts and displays a graphical image that corresponds to the pipe's condition. The scan can reveal density variations caused by corrosion, welds, wet insulation, blockages and any other change in density.

Advantages of x-ray inspection:

  • No need for costly insulation removal
  • No physical contact is required with the piping and so even high-temperature pipes can be inspected online, meaning no temperature, weather or surface condition limitations.
  • No need for surface preparation
  • Even non-magnetic, non-metallic pipes can be inspected.
  • Can detect wet insulation, which in turn will lead to CUI
  • Can detect internal erosion/corrosion and gives absolute values of remaining wall thickness

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