Structural Risk-Based Inspection (RBI)
Inspection driven by structural risk, not fixed intervals.
Inspection Driven by Structural Risk
Structural Risk-Based Inspection (RBI) is a systematic approach for determining what to inspect, where to inspect, how often to inspect, and what level of inspection is justified based on the likelihood and consequence of structural degradation or failure.
For offshore jackets, topsides, jetties, towers and other load-bearing structures, risk cannot be understood from condition data alone. A defect only becomes meaningful when its effect on the strength, fatigue life, load path, redundancy and overall structural performance is understood.
The objective of Risk-Based Inspection (RBI) is to direct inspection resources to where they are most needed.
For structures, this means identifying the members, connections and locations where deterioration is most likely to affect structural performance, safety or continued operation — and prioritising inspection accordingly.
It answers four practical questions:
The value is not in inspecting more. It is in using engineering judgement and risk to inspect more intelligently.
For offshore jackets, topsides, jetties, towers and other load-bearing structures, this requires understanding not only whether deterioration exists, but whether it matters to the way the structure carries load and performs.
When Structural RBI is Needed
Structural RBI is most valuable where inspection resources are limited and not every component can be inspected with the same frequency or level of detail.
It provides an engineering basis for identifying where deterioration is most likely to affect structural performance, and for directing inspection effort towards the areas of greatest risk.
Structural RBI is particularly useful where:
- Assets are operating at or beyond their original design life
- Inspection backlogs require prioritisation
- Inspection budgets or access are constrained
- Known or suspected degradation is present
- Operating conditions or structural loading have changed
- There is uncertainty in structural condition, capacity or remaining life
Ageing Assets
As structures age, fatigue damage, corrosion and other degradation mechanisms accumulate. Structural RBI helps distinguish between areas that can continue to be managed routinely and those where inspection or engineering assessment should be prioritised.
Inspection Backlog and Resource Constraints
Where inspection backlogs have developed, Structural RBI provides a rational basis for deciding what needs attention first. Higher-risk components can be prioritised while lower-risk items can be inspected later, helping convert a large backlog into a risk-ranked and manageable inspection programme.
Changing Operating Conditions
Changes in loading, equipment configuration, operating duty or structural modifications can alter the demands placed on a structure. Structural RBI allows the inspection strategy to be reassessed so that it remains aligned with the current structural risk profile, rather than the conditions assumed when the original inspection programme was developed.
Uncertainty in Condition or Remaining Life
Where inspection data is incomplete, degradation is poorly understood, or remaining structural capacity is uncertain, Structural RBI helps identify where additional inspection will provide the greatest reduction in uncertainty. The aim is not simply to collect more data, but to collect the right data to support engineering decisions.
How HPG Applies RBI
Gather Review Data
Company specifications, general asset information, and original design basis. Drawings, existing design, inspection or analysis reports, and maintenance records.
Identify Structural Systems and Define Sub-Systems
Sub-systems are specified in line with Safety and Environmental Critical Elements (SECE) identified against company structural and HSEQ standards.
Identify All Credible Deterioration and Failure Mechanisms
Characterise every active degradation mechanism relevant to each structural sub-system corrosion, fatigue, overstress, marine growth, CP depletion forming the basis for subsequent probability assessment.
Determine Consequence of Failure
Evaluate the potential impact of failure for each structural sub-system considering life safety, environmental exposure, production loss, and regulatory consequence.
Determine Probability of Failure
Quantify the likelihood of failure for each identified failure mechanism using degradation models, inspection data, and engineering judgement calibrated to current asset condition.
Risk Assess Structural Sub-Systems
Combine consequence and probability of failure to produce a risk ranking for each sub-system forming a transparent, auditable basis for inspection prioritisation.
Identify Inspection Requirements and Assign Frequency
Define inspection type, method, access requirement, and frequency for each sub-system based directly on its risk ranking and the failure mechanisms in scope.
Develop the Facility In-Service Inspection Plan (ISI)
Consolidate all sub-system inspection requirements into a facility-wide Risk Based In-Service Inspection Plan ready for integration with CMMS, inspection databases, and operational planning.
HPG Engineering applies Structural RBI as a continuous, risk-based decision cycle. Inspection findings are assessed against structural behaviour and degradation risk, actions are defined where required, and the inspection programme is then reassessed and updated.
The result is a dynamic inspection strategy that evolves with asset condition, operating changes and new information — following a continuous cycle of inspect, assess, act and reassess.
CONTINUOUS
INTEGRITY
DECISION
CYCLE
Collect field and operational data
Analyze structural behaviour, degradation risk
Define and implement targeted intervention
Review outcomes, update integrity models
What Sets Us Apart
Moving Beyond Traditional Structural Integrity Management
Many integrity programmes still operate through disconnected inspections, static databases, and periodic reporting. At HPG Engineering, we integrate traditionally disconnected integrity systems into a unified engineering decision environment.
Engineering-Led
Digital Integration
Connecting inspection data, structural models, maintenance schedules and periodic reporting.
Structural Models — SACS, SESAM
Integrity Databases — NEXUS/CREDO
Maintenance Systems — SAP/Maximo
Digital Twin Platforms — Cognite/AVEVA
Judgement
Supported by Up-To-Date Data
Using available tools to improve visibility of asset risk. Keeping engineering judgement at the heart of decision-making.
Near real-time visibility of evolving asset risk
Dashboards to reflect asset risk at various levels — Power BI, SharePoint, NEXUS
From Risk Ranking to Engineering Assessment
Where inspection findings or identified risks require further evaluation, we apply structural engineering analysis to determine their significance to structural performance, capacity and remaining life.
This provides a stronger technical basis for decisions on continued operation, inspection, monitoring, repair or further assessment — ensuring that integrity decisions are supported by engineering evidence, not risk ranking alone.
Global and Local Structural Analysis
Structural analysis using SACS, SESAM and ANSYS, from global system behaviour to local member, joint and connection response.
Residual Capacity Assessment
Evaluation of the effect of corrosion, section loss, damage and structural modification on remaining load-carrying capacity.
Fatigue and Remaining Life Assessment
Assessment of fatigue utilisation and remaining fatigue life, informed by inspection findings, loading history and current operating conditions.
Revalidation of the Inspection Programme
Inspection findings, engineering assessment and updated risk information are used to revalidate inspection priorities, scope and intervals for the next inspection cycle.
Aligned with Internationally Recognised Standards
Our Structural Integrity Management and Risk-Based Inspection methodologies are aligned with internationally recognised offshore standards ensuring technically robust and auditable outcomes.
Core SIM Framework
These standards underpin our lifecycle approach to inspection, reassessment, and life extension of offshore assets.
Supporting Frameworks
Used where integration with piping systems, pressure equipment, or enterprise RBI platforms is required, and where integration with the systems covered by these codes applies.
Local Frameworks
HPG Engineering applies recognised international SIM and RBI standards within the applicable Nigerian regulatory framework and NUPRC requirements.
Outputs Focused on Decision-Making
RBI outputs are not reports produced for the file. They are engineering products designed to support clear, defensible decisions on inspection, repair, deferment, or continued operation.
Risk-Ranked Inspection Plans
Component-level risk ranking across the full asset defining what to inspect, with what method, and at what frequency.
Critical Structural Element Register
A documented register of members and joints whose failure carries the greatest structural or safety consequence.
Degradation and Remaining Life Reports
Quantified remaining fatigue life, corrosion projection, and structural capacity margins calibrated to current inspection findings.
Prioritised Repair Deferment Schedules
Repair and maintenance recommendations sequenced by risk contribution, with documented justification for any deferment.
Optimised Inspection Scope
A scoped inspection programme that reduces effort on low-risk components while directing resource where it genuinely matters.
Auditable Engineering Basis
A traceable record of every risk assessment, assumption, and decision structured for regulatory, insurance, and management review.
Value to Operators
Structural RBI is not only a safety tool it is a commercial one. Engineering-led risk prioritisation translates directly into cost savings, better resource allocation, and longer asset life.
Lower Inspection Costs
Risk-informed scope reduction removes effort from low-risk components directly reducing campaign costs without compromising integrity.
Avoided Unnecessary Repair
Decisions based on condition and risk, not fixed schedules. Operators avoid premature or reactive interventions that consume budget without reducing risk.
Extended Asset Life, Justified by Engineering
A structured, documented basis for continued operation beyond design life enabling life extension decisions that withstand regulatory and lender scrutiny.
Programmes That Fit Operational Reality
Inspection and maintenance plans aligned to operational windows, shutdown cycles, and available budgets not generic intervals.
Stronger Position with Regulators and Insurers
A demonstrated, systematic approach to integrity management supports regulatory compliance and can positively influence insurance terms and premiums.
Confidence in Continued Operation
Operators can make decisions on repair, deferment, or life extension with a clear engineering basis reducing uncertainty for management, boards, and asset owners.