CUI

Module from the Refractory and Insulation Curriculum curriculum.

Module 10 - Corrosion Under Insulation (API 583) · Learning Objectives · 1. Identify CUI temperature range: 10-300F for CS; 140-350F for SS · 2. Apply barrier coating (typically 2-coat epoxy or TSA) before insulation · 3. Seal insulation + jacketing to exclude water · 4. Apply API 583 RBI approach for CUI management · 5. Inspect via strip + VT, profile RT, pulsed eddy current (PEC) through insulation · CUI Risk Factors (API 583)

Factor	Higher Risk	Lower Risk	Notes	Mitigation	Ref
Temperature	10-250F CS, 140-350F SS	Above range (dry)	Condensation zone	Upgrade or monitor	API 583
Coating condition	Damaged, worn	Good epoxy or TSA	Most important	Maintain coating	API 583
Insulation type	Mineral wool (wicks)	Cellular glass	Water absorption	Hydrophobic material	API 583
Jacket integrity	Leaking joints	Sealed aluminum	Entry points	Maintain, re-caulk	API 583
Service location	Outdoor, horizontal	Indoor, vertical	Rain access	Caulk joints	API 583
Age	> 10-20 yr	< 5 yr	Degraded coating	Rehab	API 583
CI species	Chloride containing	Plain water	Worse for SS	Barrier coat	NACE

Source: Refractory_Insulation_Curriculum_v1.xlsx · Sheet: CUI

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