Multi-Phase CUI Integrity Management Program for LNG Facility Assets
TES Canada supported a Canadian LNG facility operator with a multi-phase CUI integrity management program, combining field inspection, risk-informed prioritization, a plant-wide CUI manual, and a digital reassessment tool to support sustainable integrity decisions.
Operational Context
A Canadian LNG facility operator identified localised Corrosion Under Insulation concerns on insulated process equipment within their facility. The plant operates insulated piping systems, pressure vessels, heat exchangers, and associated pressure equipment across multiple process areas — all subject to the temperature cycling, moisture ingress risk, and insulation degradation conditions that drive CUI.
The operator recognised that a reactive, location-by-location response was insufficient. A structured, plant-wide approach was needed to understand the true extent of CUI exposure across the insulated asset population, prioritise inspection resources, and establish a defensible long-term management framework that could be sustained and updated internally.
Engineering & Integrity Challenge
The core challenge was that CUI risk was largely invisible. Insulation covered the asset population, masking coating condition, surface degradation, and early-stage wall loss from routine inspection. The operator needed to answer three critical questions without resorting to blanket insulation removal: Where is CUI risk concentrated across the facility? What is the actual condition of insulation, coatings, and pipe wall at the highest-risk locations? And how should inspection, remediation, and re-inspection be managed on a plant-wide basis going forward?
The scope covered more than 120 insulated assets in the initial assessment phase, expanding to encompass more than 300 insulated piping isometrics across the full plant in the final phase.
Why the Situation Was Complex
CUI is inherently hidden. Unlike visible corrosion, CUI progresses beneath insulation with no external indication until significant wall loss has occurred or insulation jacketing is disturbed. This makes conventional inspection techniques ineffective without either removal of insulation or application of specialist through-insulation methods.
Blanket insulation removal was not viable. Removing insulation across the asset population would have caused significant operational disruption, damaged serviceable insulation systems, and created unnecessary cost without proportionate integrity benefit.
Data gaps were significant. Coating system records, insulation installation dates, and prior inspection findings were incomplete or inconsistent across the asset population — requiring engineering judgement to interpret partial records and establish defensible baseline risk ratings.
Operating temperature ranges at LNG facilities intersect with the most active CUI temperature window defined in API RP 583, placing a large proportion of the insulated asset population within elevated risk categories by default.
The operator required a program that could be sustained and updated internally — not one dependent on recurring external engineering support for routine risk reassessment cycles.
TES Engineering Thinking
TES Canada structured the engagement as a three-phase program, with each phase building on the findings and data from the previous.
Phase 1 — Pre-FEED CUI Assessment and Data Foundation: TES Canada began by collating existing records — P&IDs, isometric drawings, inspection histories, and maintenance records — and developing a structured insulated asset register covering the initial asset population. Each asset was assessed against the CUI driver variables defined in API RP 583 and EFC 55: operating temperature, insulation type and condition, climate exposure, coating age, and geometry. An API RP 581-style risk-informed prioritisation was applied, combining likelihood of CUI occurrence with consequence of failure to rank the asset population and focus Phase 2 survey resources on the highest-risk locations.
Phase 2 — Pretreatment Area CUI Surveys and Integrity Planning: TES Canada conducted systematic visual CUI surveys across the pretreatment process area. Insulation jacketing integrity, sealant condition, penetrations, support saddle regions, and dead-leg locations were inspected and classified. At selected high-priority locations, through-insulation digital radiography was applied — imaging pipe wall condition from outside the insulation system without removal. Where RT findings or insulation condition warranted closer examination, targeted insulation removal was carried out. Exposed metal and coating surfaces were assessed against SSPC / NACE / ISO 8501-1 criteria. Where wall loss was confirmed, API 579-1 / ASME FFS-1 fitness-for-service principles were applied to evaluate component integrity status and establish re-inspection intervals under API 510 and API 570.
Phase 3 — Plant-Wide CUI Program, Manual, and Digital Risk Tool: The methodology developed and field-validated in Phases 1 and 2 was scaled to the full facility. TES Canada extended the insulated asset register to cover the complete plant, developed a plant-wide CUI Program Manual, and designed and built an Excel-based digital risk reassessment and inspection planning tool. The manual documents inspection philosophy, screening criteria, risk prioritisation methodology, field procedures, acceptance criteria, and remediation guidance in a single auditable document. The digital tool provides risk scoring, inspection dashboards, re-inspection scheduling, and repair traceability — enabling the operator to update risk assessments as new inspection data is gathered and manage the CUI program internally.
Technical Approach
Practical Outcome
The multi-phase program delivered a complete CUI integrity management system for the operator. The insulated asset register — initially covering more than 120 assets and extended plant-wide to encompass more than 300 piping isometrics — provided the data foundation for all inspection planning and risk reassessment activities going forward.
Risk-informed prioritisation directed field resources to the locations with the highest CUI consequence and likelihood, avoiding unnecessary insulation disturbance across the lower-risk asset population. Through-insulation radiography and targeted insulation removal provided direct, field-verified evidence of pipe wall and coating condition at the locations that mattered most — replacing assumptions with documented inspection records.
Early-stage CUI concerns were identified and documented before progressing to significant wall loss, enabling cost-effective remediation. The plant-wide CUI Program Manual established a consistent, auditable basis for all future CUI inspection and remediation decisions. The digital risk reassessment tool enabled the operator to update risk scores as new inspection data is gathered, track repair history, and produce management-ready dashboards — supporting long-term governance without dependency on external engineering support.
Lessons Learned
CUI risk prioritisation is only as good as the data behind it. Incomplete coating records and insulation installation histories are the norm — engineering judgement in interpreting partial records is a core competency, not a workaround.
Through-insulation radiography is a high-value technique for CUI screening, but effectiveness depends on selecting the right locations. RT applied without risk-informed pre-screening generates noise, not intelligence. The Phase 1 prioritisation work was what made the Phase 2 RT program efficient and purposeful.
A CUI program manual is only valuable if it reflects actual field conditions and is written for the people who will use it. Generic templates fail. The manual produced here was built from data gathered in Phases 1 and 2 — specific to this asset population, risk profile, and operational context.
Digital tools for ongoing CUI management do not need to be complex to be effective. An Excel-based tool built around the right risk logic, with clear dashboards and traceability, can sustain a plant-wide CUI program for years without specialist software or recurring external engineering support.
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