X-Radiography

Definition - What does X-Radiography mean?

An X-radiography is an X-ray inspection technique that is used to detect corrosion in materials and structures that operate in highly corrosive environments. For example, it is used as a real-time digital imaging system to detect flaws in offshore rigs that are continuously submerged in water. To carry out such an inspection, the sample areas have to be identified within the circuit and there is no need for the insulation to be removed.

Petropedia explains X-Radiography

X-radiography utilizes the principle of radiography, which 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 other changes in density.

Advantages:

  • 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.
  • It can detect wet insulation, which in turn will lead to corrosion under insulation (CUI).
  • It can detect internal erosion/corrosion and gives absolute values of remaining wall thickness.
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