corrosion under insulation, temperature ranges of roughly 10-350°F (-12 to 175°C) for carbon steel and about 140-400°F (60-205°C) for external chloride SCC of austenitic stainless (check the current API 571/583), susceptibility matrix, inspection strategy. Catalogued by API 571 as a major damage mechanism affecting fixed equipment in refining and petrochem. This guide walks through mechanism, susceptibility, detection, and prevention.
\nCorrosion under insulation (CUI) is external corrosion of carbon and low-alloy steel, or external chloride stress corrosion cracking of austenitic stainless steel, under wet insulation. Water enters through damaged jacketing, sealing or penetrations and is held against the metal; corrosion is most aggressive in the temperature range where water is present but evaporates slowly. Reference: API RP 571 (3rd ed.) paragraph 3.22 and API RP 583.
\nTechnique selection should follow the damage mechanism, with procedures approved under the employer's written practice.
\nOwners that run risk-based inspection (API RP 580/581) use damage-mechanism susceptibility and measured inspection results to set inspection priorities and intervals, and damage beyond code acceptance may be referred for an engineering fitness-for-service assessment (API 579-1/ASME FFS-1). Both are owner and engineering responsibilities; Atlantis NDT does not provide RBI or FFS services. The Atlantis Digital Twin platform can display the underlying inspection data on a 3D model.
\nA: Visual inspection of insulation and jacketing to locate damage; targeted insulation removal at likely locations, then visual and UT thickness.
\nA: API RP 571 (3rd ed.) paragraph 3.22 and API RP 583. API RP 571 describes the mechanism, critical factors, affected equipment and inspection and monitoring options.
\nA: The owner's authorized inspector under API 510, 570 or 653, or the owner's RBI assessment where one is used. Atlantis NDT does not provide RBI services.
\nA: With ASNT Level III consulting on NDE procedures and technique selection, ASNT SNT-TC-1A training for the technicians who perform the examinations, and inspection software (Atlantis ERP and the Digital Twin platform) that holds the inspection records.
\nRecommended practices and guides inform an inspection programme; binding requirements come from the in-service codes (API 510, API 570, API 653), the construction codes and the regulations that apply to the asset. NDE personnel are qualified under the employer's written practice (commonly ASNT SNT-TC-1A, ANSI/ASNT CP-189 or ISO 9712), and NDE procedures are approved by the employer's NDT Level III. Acceptance of indications follows the governing code; damage beyond its rules may be referred for an engineering fitness-for-service assessment (API 579-1/ASME FFS-1), which Atlantis NDT does not perform. Keep procedure revisions, calibration records and personnel certifications traceable; Atlantis ERP can hold these records.
\nUse the edition required by the contract, governing requirements and applicable jurisdiction. Record that edition in the procedure and evaluate changes before adopting a later publication.
\nA: 4-20 weeks depending on team size + scope. SMB: 4 weeks. Mid-size: 8-12 weeks. Enterprise multi-region: 12-20 weeks. Atlantis NDT delivers phased rollout with clear milestone gates.
\nA: No — pricing varies by region, scope, delivery model, and team size. Atlantis NDT is positioned as affordable, accessible, and fully customizable. Free 30-min consultation + tailored quote.
\nA: Atlantis ERP has an open REST API, so it connects to SAP, Maximo, NetSuite or any other system that accepts API connections; each integration is scoped with you during implementation. Free integration scoping consultation.
\nA: Request a free 30-min consultation at /contact. We reply within one business day. We scope your asset class + damage mechanisms + code requirements + delivery model preference + integration needs in a single call.
\nAtlantis NDT — led by Anoop Rayavarapu (ASNT NDT Level III in UT, RT, MT, PT and VT). Free consultation. request a free consultation. Pricing varies by region and scope.
","order":0,"createdAt":"2026-06-24","updatedAt":"2026-10-18","quickAnswer":{"question":"What is Corrosion Under Insulation (CUI) 2026 and how do I detect it?","answer":"Corrosion under insulation (CUI) is external corrosion of carbon and low-alloy steel, or external chloride stress corrosion cracking of austenitic stainless steel, under wet insulation. Water enters through damaged jacketing, sealing or penetrations and is held against the metal; corrosion is most aggressive in the temperature range where water is present but evaporates slowly. Informational guide by an ASNT NDT Level III; RBI and FFS decisions stay with the owner.","bullets":["Operating temperature in the susceptible range (for carbon steel roughly 10F to 350F, -12C to 175C, per API RP 571) or cyclic and intermittent service","Detection: Visual inspection of insulation and jacketing to locate damage","Mitigation: High-quality coating under the insulation (for example thermally sprayed aluminium or immersion-grade coatings)"]}}