Flange Inspection

IRISNDT inspects in-service raised face flanges with phased array ultrasonic testing (PAUT); we detect bore wall loss and flange face damage without having to disassemble flanges. The technique detects flange ID bore and raised face wall losses.

Typical Applications Include:

  • Raised face flange corrosion losses inspections.
  • Most raised face flanges from Class 150 to Class 2500 can be inspected.
  • Flange pre-shutdown inspections to identify maintenance requirements.
  • High-wear service monitoring of flanges to determine remaining lifetime.


  • Flanges can be inspected without needing to disassemble, which is a significant cost savings for large diameter and/or high class flanges.
  • The data is permanently recorded to allow audit or future damage monitoring.
  • Both sides of the flange are typically inspected at the same time.


  • The skin temperature of the OD surface of the flange must be below 100 °C to perform PAUT consistently.
  • Ultrasonic testing requires access to the OD of the flange and an ultrasonic surface quality.
  • This technique does not identify flange face isolated worm-type corrosion reliably.

Flange Inspection Fundamentals:

With phased array ultrasonic testing (PAUT) the tester manipulates multi-element probes to modify beam properties such as angle, standoff distance and focal properties.  Phased array inspection has gained wide acceptance in the inspection community due to its flexibility and the small portable systems now commercially available.

To inspect the raised flange face area, encoded magnetic scanners direct sound from the OD of the flange between the bolt holes.  With PAUT one can engineer the ultrasound angles to fit the specific flange geometry.  As well, the multiple ultrasound angles can be used to optimize data displays of corrosion and/or erosion in flanges.