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Corrosion Under Insulation

CUI – Corrosion Under Insulation



Most operators deal with Corrosion Under Insulation (CUI) across the world. In some cases, in order to preserve the process conditions the pipe must be insulated. This insulation, at a specific temperature range while using carbon steel for the pipe, produces moisture. These conditions, as well as other factors, can produce external corrosion, called Corrosion Under Insulation (CUI). Left to its own devices, CUI can cause serious problems and even catastrophic consequences.

The US Chemical Safety Board issued a report in 2008 stating “The highest incidence of reported leaks in refining and chemical industries are due to CUI and not to internal process corrosion.” CUI is being recognized in the industry as a unique damage mechanism (API RP 583).

This hidden enemy provides a challenge to the Inspection, Reliability, and Maintenance departments. Due to the unpredictable nature of CUI, identifying, tracking, and mitigating CUI across assets can have many barriers. The work process is typically addresses with API 510 and 570 Visual Inspectors that are technically proficient in identifying the “tell tale” evidence of CUI, simultaneously checking and identifying external location categories where moisture is trapped under insulation.



Unless the operator completely coats the carbon steel, it is likely CUI can never be completely mitigated. The challenges consist in three primary areas.

  1. The continuous plan, do, check, act process where baselines are established, follow up is often required, and future work may need to be scheduled (some years out) and tracked for execution produces a lot of data. The analysis of this data, and the associated documentation, is next to impossible to track via spreadsheets or on a corporate file server. Due to the continuous ever mitigating nature of CUI over an extended period of time, this process can be unsustainable.
  2. Process and service changes to the plant, such as changing the temperature, are often not communicated to the personnel who understand how to inspect and identify CUI.
  3. The Pipe components, or lines, are often not described in sufficient levels of detail within Enterprise Resource Planning (ERP), or Enterprise Asset Management (EAM), to communicate to the appropriate stakeholders when changes to the Pipe occur. This may include replacement, stripping of insulation, re-coating, or possibly jacket changes. All of these changes need to be properly communicated to the team managing CUI program for assessment and action (if any).


There’s no substitute for qualified personnel, procedures, and a management process to put together a good CUI program, but these alone will not address the problem statement.

A digital solution must be put in place to perform the assessment for CUI, identify mitigating actions (current, follow-up, and future), understand process and physical changes, in an effort to communicate to all stakeholders who are address Loss of Containment (LoC) due to CUI.

There are two software solutions on the market today that addresses this need. They are:

  1. SAP Asset Strategy and Performance Management (ASPM) in conjunction with the AsInt CUI Assessment Library and AsInt Inspection Apps. Both of these additions plug directly into SAP ASPM as “Apps” or content to feed the SAP Assessment capabilities.
  2. AsInt’s CORE CUI App. This is a web application that performs all of the necessary identification, planning, and mitigation steps.



  • AsInt CUI Web App – Performs all of the functions required, however, it is not embedded within SAP, though can communicate notifications and work orders.


A sustainable CUI program over a 5, 10, 15 year period. Communicating critical information to all key stakeholders to identify, mitigate, and avoid a Loss of Containment due to CUI.