Using Pulsed Eddy Current Testing to Manage Corrosion Under Insulation

Using Pulsed Eddy Current Testing to Manage Corrosion Under Insulation

Posted 04 September 2019

Corrosion under insulation (CUI) remains one of the greatest concerns for the integrity of many millions of kilometres of insulated industrial piping and insulated vessels, risking production and safe operation on a daily basis.

Its causes are often simple however its management remains an ongoing challenge due to the insulation itself typically hiding the extent of the problem. Industry has no “silver bullet” for the detection and quantification of CUI. However, through combining inspection screening methods, a reliable understanding of the presence and extent of CUI can be achieved.

ALS continues to develop and deliver both conventional and advanced inspection techniques into our offering for CUI assessment.

This article discusses pulsed eddy current testing (PECT) and its advantages for assessing CUI.

Common CUI scenarios that need to be considered to ensure asset integrity:

  • Areas exposed to mist overspray from cooling towers
  • Piping close to steam vents
  • Insulated piping close to deluge systems
  • Carbon steel piping operating between -5 & 120°C
  • Dead Legs and piping attachments through insulation
  • Steam traced lines which may have steam leaks
  • Damaged insulation
  • Cracks in fireproofing
  • Evidence of brown staining on insulation

How we evaluated PECT for assessing CUI

We researched and trialed PECT systems looking for their ability to detect different corrosion geometries, such as pitting and general corrosion, and enhance scanning productivity.

Following from these trials, we have selected specific PECT systems which provided the best piping, vessels and tanks screening outcomes.

Finally, we trained our staff in application of the technique to ensure a reliable high-quality service as would be expected by our clientele and required of under our accreditations.

Combined with our other inspection methods, our capability for cost effective CUI assessment was enhanced with the addition of PECT.

Corrosion of pressure vessel
Close-up of corrosion

Where can PECT add benefits

Using a different current form to create a wide frequency band width, PECT provides an ability to inspect items without direct contact.

This leads to advantages such as:

  • The technique can penetrate thick insulation or fireproofing;
  • Composite repair materials can be scanned through where wall loss has already occurred;
  • Chicken wire and re-bar do not affect analysis; and,
  • Scanning can be performed with plant on line.

Through our experienced team:

  • Scanning can be performed using rope access minimising the need for expensive scaffolding;
  • Results can be seen in real time;
  • Many meters of piping can be scanned per shift; and,
  • CUI, internal pitting type corrosion and general wall loss can be detected.

Combining inspection effectively to meet your asset management needs

Adding PECT into your tool belt for understanding CUI in your insulated systems is one way ALS is delivering effective assessment.

Another way is by ensuring that you use PECT effectively, and combined it appropriately, with the full range of inspection and engineering solutions available to manage your insulated piping and vessels.

ALS inspection and engineering staff can help you understand:

  • The real risk of failure due to CUI;
  • The most cost-effective technique(s) to use to examine for CUI; and,
  • The extent of examination that is needed to appropriately manage CUI for your asset’s risk profile.

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