Maintaining Technical Integrity of Petroleum Flowlines on Offshore Installations: A Decision Support System for Inspection Planning

2010 ◽  
Author(s):  
R. M. Chandima Ratnayake ◽  
Tore Markeset
Keyword(s):  
Ad Hoc ◽  
Oil And Gas ◽  
Formal Model ◽  
Technical Condition ◽  
Inspection Planning ◽  
Analytic Hierarchy ◽  
Plant Strategy ◽  
The North ◽  
Critical Components ◽  
Inspection Data

Oil and Gas (O&G) platforms in the North Sea are facing aging problems as many of the installations have matured and are approaching their design lifetime. Flowlines are used to transport oil and gas well stream from the wellhead to the production manifold. They are categorised as one of the most critical components on a production facility. Flowline degradation takes place due to corrosion and erosion. The deterioration of a flowline may increase the risk of leakages, ruptures, etc., which shall lead to serious HSE (health, safety and environmental) and financial consequences. Any such risks have a direct impact on the O&G installation’s technical integrity as well as the operator’s sustainability concerns. Conventionally, pipelines are designed with safety provisions to provide a theoretical minimum failure rate over the life span. Furthermore, to reduce the risk of failure various techniques are routinely used to monitor the status of pipelines during the operation phase. The existing methods of flowline health monitoring planning requires one to take into consideration the operator’s plant strategy, flowline degradation mechanisms, historical data, etc. A technical condition report is made based on findings’ reports and degradation trends. This report recommends the inspection of a number of points on the flowlines in a certain year using non-destructive evaluation methods such as visual inspection, ultrasonic testing, radiographic testing, etc. Based on the technical condition report, in general for a certain preventive maintenance shutdown, 10 to 15 flowline inspection openings are accommodated as finance, time and resource availability are taken into consideration. However, it is customary to plan to open more locations in a certain inspection package than can be inspected and minimization of such points is at present done on an ad hoc basis. This paper suggests a formal model and a framework to formally minimize the number of visual inspections by executing the plant strategy as well as HSE concerns. The model is derived using analytic hierarchy process (AHP) framework, which is a multi-criteria decision-making approach. The model is developed based on literature, industrial practice, experience as well as real inspection data from a mature offshore O&G installation located on the Norwegian Continental Shelf.

Utilization of Piping Inspection Data for Continuous Improvement: A Methodology to Visualize Coverage and Finding Rates

2013 ◽  
Author(s):  
R. M. Chandima Ratnayake
Keyword(s):  
Ad Hoc ◽  
Oil And Gas ◽  
Thickness Measurement ◽  
Gas Production ◽  
Process Conditions ◽  
Inspection Planning ◽  
Oil And Gas Production ◽  
Product And Process ◽  
Inspection Data ◽  
The Right

Piping inspection in Oil and Gas (O&G) production and process facilities (P&PFs) is traditionally set up by dividing the overall piping components into corrosion loops (CLs) reflecting similar corrosion (i.e. corrosion due to chemical or electro-chemical reaction and/or erosion-corrosion) environment and process conditions. Each CL is comprised of a few or several wall thickness measurement locations (WTMLs). The WTMLs are typically identified for each WTML ‘feature’ (e.g. straight section of a spool, bend, tee, weld, end cap, etc.) in a CL. Generally, inspection planning decisions regarding WTMLs are prioritized based on the results of risk based inspection (RBI) analysis. However, the degradation behavior is continuously changing due to the change in product and process conditions during the maturity of O&G production wells. This manuscript illustrates a methodology to visualize inspection coverage and corresponding defect finding rates (DFRs) for different WTML features in a selected sub-system of an oil and gas production and process facility. The suggested methodology aids the visualization of DFRs pertaining to different WTMLs, enabling inspection planners to assign inspection recommendations to the right location at the right time, minimizing ad hoc work. The approach also enables feedback to be provided to the plant inspection strategy (PIS), depending on the corresponding production field and P&PF, whilst reducing the cost of inspection to the asset owner by the minimization of ad hoc inspection recommendations.

Asset Integrity Control: Prioritization of Offshore Topside Flange Openings During Preventive Maintenance Shutdowns

2019 ◽  
Author(s):  
R. M. Chandima Ratnayake
Keyword(s):  
Preventive Maintenance ◽  
Ad Hoc ◽  
Oil And Gas ◽  
Complex Geometries ◽  
Illustrative Case ◽  
Destructive Testing ◽  
Analytic Hierarchy ◽  
Illustrative Case Study ◽  
Inspection Data ◽  
And Control

Abstract Top side flange inspection on offshore production and process facilities (P&PFs) has been a challenging task, due to complex geometries, produced crude oil and gas quality changes over the production well’s maturity, as well as the stringent regulatory requirements that need to be followed to assure the anticipated integrity of the operating assets. The complex geometries hinder the use of non-destructive testing (NDT) testing approaches and necessitate shutting down the system or subsystem in order to disassemble the flange to perform close visual inspection (CVI). Using risk-based asset integrity (AI) assessment and control (RBAIA&C) approaches, it is possible to classify the flanges into different classes, according to probability of failure (PoF). The PoF is estimated by considering the last inspection date, past inspection data, findings from similar locations/systems in the same offshore facility, etc. Together with consequence of potential failures (CoF), it is possible to estimate the risk of a potential failure due to the loss of integrity of a selected flange. Although several flanges are qualified to be disassembled, based on RBAIA&C activities, it is not possible to take all of them off during a certain preventive maintenance (PM) shutdown. Currently, ad hoc approaches have been used to further prioritize the flanges that have been recommended for inspection during a PM shutdown, based on RBAIA&C activities. The aforementioned jeopardizes the integrity of flanges and subsequently the overall system, possibly leading to catastrophic accidents. This manuscript demonstrates a methodology for the systematic further prioritization of flanges that need routine CVI. The flange inspection related system analytics have been incorporated with the analytic hierarchy process (AHP) to make logical further prioritization with sufficient transparency. The approach has been demonstrated with an illustrative case study that has been chosen from an offshore P&PF. A sensitivity analysis has also been performed and is presented to demonstrate how to carry out trade-off evaluations between different factors in the flange prioritization in a PM shutdown.

Field Implementation of RBI for Jacket Structures

2003 ◽  
Author(s):  
Michael H. Faber ◽  
Daniel Straub ◽  
John D. So̸rensen ◽  
Jesper Tychsen
Keyword(s):  
Sensitivity Analysis ◽  
Data Base ◽  
Stress Ratio ◽  
Oil And Gas ◽  
Inspection Planning ◽  
The North ◽  
Large Numbers ◽  
Structural Details ◽  
Jacket Structures ◽  
The North Sea

The present paper first gives a brief outline of the simplified and generic approach to reliability and risk based inspection planning and thereafter sets focus on a recent application of the methodology for planning of in-service NDT inspections of the fixed offshore steel jacket structures in the DUC concession area in the Danish part of the North-Sea. The platforms are operated by Maersk Oil and Gas on behalf of DUC partners A.P. Mo̸ller, Shell and Texaco. The study includes a sensitivity analysis performed for the identification of relevant generic parameters such as the bending to membrane stress ratio, the design fatigue life and the material thickness. Based on the results of the sensitivity analysis a significant number of inspection plans were computed for fixed generic parameters (pre-defined generic plans) and a data-base named iPlan was developed from which inspection plans may be obtained by interpolation between the pre-defined generic plans. The iPlan data-base facilitates the straightforward production of large numbers of inspection plans for structural details subject to fatigue deterioration. In the paper the application of the generic inspection plan database iPlan is finally illustrated on an example.

Integrity inspection planning updated with cost of risk

2017 ◽  
Vol 57 (2) ◽  
pp. 647
Author(s):  
Yury Sokolov
Keyword(s):  
Oil And Gas ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Individual Risk ◽  
Plant Management ◽  
Inspection Planning ◽  
Worst Case ◽  
Integrity Management ◽  
Inspection Data ◽  
New Generation

The industry expenditure savings motive requires a cost/benefit analysis to optimise Integrity Management budgets. The challenge of estimating precise risk costs requires that numeric Probabilities of Failure (PoF) be known at the highest possible level of confidence, as equipment items specific PoFs govern the actual probability of financial losses and safety implications. The first-hand information on the equipment actual integrity condition is contained in numeric results of integrity inspections. In practice, these results are seldom analysed statistically, being collapsed into single ‘worst case’ values. This simplification prevents assessing of equipment specific actual PoFs and from quantifying failure risks when using traditional methods. We developed a new-generation inspection planning and assessment strategy applied to oil and gas pressure equipment. Evaluating equipment PoFs enables assessing risk costs and optimising the budgets, as well as setting justified internal inspection coverage and frequency objectives. This is achieved by a statistical analysis of numeric inspection data. Existing inspection data (such as ultrasonic testing spot-checks) can be used for a first-pass analysis. Statistical plotting of such data automatically visualises the data quality, and the relevant recommendations for improving inspection coverage or tools are drawn where necessary. We found that two criteria drive integrity decision making: failure total costs and annual fatality expectancies. These criteria are mutually complementary. Both need to be considered for a safe and profitable plant operation. Equipment individual risk control strategy is then developed from safety compliance and budget savings maximising standpoints, thereby also enabling confident design and procurement decisions. This is a new-generation strategy suitable for bringing together all branches of plant management and for improving confidence of the parties. We see it as an evolutionary update to Risk Based Inspection and Maintenance practice, which is now in high demand due to cost pressures.

Risk Based Inspection Planning for Deteriorating Pressure Vessels

2016 ◽  
Author(s):  
Shane Haladuick ◽  
Markus R. Dann
Keyword(s):  
Decision Analysis ◽  
Decision Maker ◽  
Pressure Vessel ◽  
Oil And Gas ◽  
Pressure Vessels ◽  
Inspection Planning ◽  
Course Of Action ◽  
Inspection Data ◽  
The Cost ◽  
Aid Decision

Pressure vessels are subject to deterioration processes, such as corrosion and fatigue. If left unchecked these deterioration processes can lead to failure; therefore, inspections and repairs are performed to mitigate this risk. Oil and gas facilities often have regular scheduled shutdown periods during which many components, including the pressure vessels, are disassembled, inspected, and repaired or replaced if necessary. The objective of this paper is to perform a decision analysis to determine the best course of action for an operator to follow after a pressure vessel is inspected during a shutdown period. If the pressure vessel is inspected and an unexpectedly deep corrosion defect is detected an operator has two options: schedule a repair for the next shutdown period, or perform an immediate unscheduled repair. A scheduled repair is the preferred option as it gives the decision maker lead time to accommodate the added labour and budgetary requirements. This preference is accounted for by a higher cost of immediate unscheduled repairs relative to the cost of a scheduled repair at the next shutdown. Depending on the severity of deterioration either option could present the optimal course of action. In this framework the decision that leads to the minimum expected cost is selected. A stochastic gamma process was used to model the future deterioration growth using the historical inspection data, considering the measurement error and uncertain initial wall thickness, to determine the probability of pressure vessel failure. The decision analysis framework can be used to aid decision makers in deciding when a repair or replacement action should be performed. This method can be used in real time decision making to inform the decision maker immediately post inspection. A numerical example of a corroding pressure vessel illustrates the method.

TBE in Italy

2020 ◽  
Keyword(s):  
Surveillance System ◽  
Ad Hoc ◽  
National Level ◽  
Case Series ◽  
Incidence Rates ◽  
Mountainous Regions ◽  
North East ◽  
The North ◽  
Tick Borne Encephalitis ◽  
Low Incidence

Italy is considered a low-incidence country for tick-borne encephalitis (TBE) in Europe.1 Areas at higher risk for TBE in Italy are geographically clustered in the forested and mountainous regions and provinces in the north east part of the country, as suggested by TBE case series published over the last decade.2-5 A national enhanced surveillance system for TBE has been established since 2017.6 Before this, information on the occurrence of TBE cases at the national level in Italy was lacking. Both incidence rates and the geographical distribution of the disease were mostly inferred from endemic areas where surveillance was already in place, ad hoc studies and international literature.1

Geothermal condition and outlook for oil and gas deposits in the north-west Black Sea shelf

2002 ◽  
Vol 8 (2-3) ◽  
pp. 206-208
Author(s):  
V.G. Osadchyi ◽  
◽  
O.A. Prykhod'ko ◽  
I.I. Hrytsyk ◽  
◽  
...  
Keyword(s):  
Black Sea ◽  
Oil And Gas ◽  
North West ◽  
The North ◽  
West Black Sea
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