Pipeline Mechanical Damage Integrity Management Framework

Author(s):  
Vlado Semiga ◽  
Sanjay Tiku ◽  
Aaron Dinovitzer

With the resolution and capabilities of the latest generation multi-sensor in-line inspection tools, detection and sizing of mechanical damage (i.e. dents, metal loss, etc) and their interaction is becoming more prevalent. As a result, the number of features requiring consideration in terms of integrity assessment is ever increasing. The following paper presents a mechanical damage integrity management framework, intended to allow the assessment of a large number of features to support maintenance planning decisions. The framework is centred around organizing and collecting features into groups that share similar integrity driving parameters. An example demonstration of the framework is also presented using the results of a single ILI run on a small diameter pipeline. The example assessment focuses on shallow dents interacting with metal loss features where the metal loss features are treated as localized, gouge-like features.

Author(s):  
Gurumurthy Kagita ◽  
Gudimella G. S. Achary ◽  
Mahesh B. Addala ◽  
Balaji Srinivasan ◽  
Penchala S. K. Pottem ◽  
...  

Abstract Mechanical damage in subsea pipelines in the form of local dents / buckles due to excessive bending deformation may severely threaten their structural integrity. A dent / buckle has two significant effects on the pipeline integrity. Notably, residual stresses are set up as result of the plastic deformation and stress concentrations are created due to change in pipe geometry caused by the denting / buckling process. To assess the criticality of a dent / buckle, which often can be associated with strain induced flaws in the highly deformed metal, integrity assessment is required. The objective of this paper is to evaluate the severity of dent / buckle in a 48” subsea pipeline and to make the rerate, repair or replacement decision. This paper presents a Level 3 integrity assessment of a subsea pipeline dent / buckle with metal loss, reported in in-line inspection (ILI), in accordance with Fitness-For-Service Standard API 579-1/ASME FFS-1. In this paper, the deformation process that caused the damage (i.e. dent / buckle) with metal loss is numerically simulated using ILI data in order to determine the magnitude of permanent plastic strain developed and to evaluate the protection against potential failure modes. For numerical simulation, elastic-plastic finite element analyses (FEA) are performed considering the material as well as geometric non-linearity using general purpose finite element software ABAQUS/CAE 2017. Based on the numerical simulation results, the integrity assessment of dented / buckled subsea pipeline segment with metal loss has been performed to assess the fitness-for-service at the operating loads.


Author(s):  
Luis A. Torres ◽  
Matthew J. Fowler ◽  
Jordan G. Stenerson

Integrity management of dents on pipelines is currently performed through the interpretation of In-Line Inspection (ILI) data; this includes Caliper, Magnetic Flux Leakage (MFL), and Ultrasonic Testing (UT) tools. Based on the available ILI data, dent features that are recognized as threats from a mechanical damage perspective are excavated and remediated. Federal codes and regulations provide rules and allow inference on what types of dent features may be a result of mechanical damage; nonetheless, there are challenges associated with identifying dents resulting from mechanical damage. One of the difficulties when managing the mechanical damage threat is the lack of information on how MFL and UT ILI tool performance is affected by dented areas in the pipe. ILI vendors do not offer any technical specifications for characterizing and sizing metal loss features in dents. It is generally expected that metal loss tool performance will be affected in dented areas of the pipe, but it is not known to what degree. It is likely that degradation will vary based on feature shape, sensor design, and sensor placement. Because metal loss tool performance is unknown within the limits of the dented pipe, other methods for recognizing mechanical damage have been incorporated into the management strategies of mechanical damage. Some of these methods include strain based assessments and characterization of shape complexity. In order to build a more effective integrity management program for mechanical damage, it is of critical importance to understand how tool technology performance is affected by dented areas in the pipe and what steps can be taken to use ILI information more effectively. In this paper, the effectiveness of MFL and UT wall measurement tools in characterizing and sizing metal loss features within dents is studied by evaluating against field results from non-destructive examinations of mechanical damage indications. In addition, the effectiveness of using shape complexity indicators to identify mechanical damage is evaluated, introducing concepts such as dents in close proximity and multi-apex dents. Finally, the effectiveness of ILI tools in predicting dent association with girth welds is also explored by comparing ILI and field results.


Author(s):  
Kevin Spencer ◽  
Wilson Santamaria ◽  
Jane Dawson ◽  
Hong Lu

The performance of older ERW pipelines has raised concerns regarding their ability to reliably transport product to market. Low toughness or “dirty” steels combined with time dependent threats such as surface breaking defects, selective corrosion and hook cracks are especially of concern in hazardous liquid pipelines that are inevitably subject to cyclic loading, increasing both the probability and rate of crack growth. The existing methods of evaluating seam weld flaws by hydrostatically testing the pipeline or In-Line Inspection (ILI) with an appropriate technology are well established. Hydrostatic testing, whilst providing a quantified level of safety is often impracticable due to associated costs, logistics and the possibility of multiple failures during the test. ILI technologies have become more sophisticated and as a result can accurately detect and size both critical and sub-critical flaws within the pipeline. However, the vast amounts of data generated can often be daunting for a pipeline operator especially when tool tolerances and future growth are required to be accounted for. For either method, extensive knowledge of the benefits and disadvantages are required to assess which is the more appropriate for a particular pipeline segment. This paper will describe advances in the interpretation of seam weld flaws detected by ILI and how they can be applied to an Integrity Management Plan. Signal processing improvements, validated by in-field verifications have enabled detailed profiles of surface breaking defects at seam welds for ERW pipelines to be determined. Using these profiles along with established fracture and fatigue analysis methods allows for reductions in the unnecessary conservatism previously associated with the assessment of seam weld flaws detected by ILI. Combining these results with other available data, e.g. dig verifications, previous hydrostatic testing records, enables more realistic and better-informed integrity and maintenance planning decisions to be made. A real case study conducted in association with a pipeline operator is detailed in the paper and quantifies the benefits that can be realised by using these advanced assessment techniques, to safely and economically manage their assets going forward.


Author(s):  
Ming Gao ◽  
Ravi Krishnamurthy

Integrity management of dent and dent associated with metal loss requires knowledge of in-line inspection (ILI) technologies, government regulations and industry codes, prescriptive requirements, and most importantly assessment models to estimate severity of the mechanical damage. The assessment models have greatly relied on the assumed capabilities of current ILI technologies to detect, discriminate and size the mechanical damage. Therefore, an investigation of the current ILI technologies and validation of their capabilities are practically important. In this paper, the current status of ILI technologies for dent and dent with metal loss is reviewed. Validation data provided by ILI inspection vendors and pipeline operators are analyzed in terms of probability of detection (POD), probability of identification (POI), probability of false call (POFC), and sizing accuracy using binomial probability distribution and confidence interval methods. Linear regression analysis is also performed to determine sizing error bands. High resolution pull test data validated with LaserScan 3-D mapping technology is used to demonstrate a better evaluation of ILI performance with minimized in-ditch measurement errors and the effect of change in dent geometry and dimension due to re-bounding and re-rounding. Issues associated with field measurement and improvement are discussed.


Author(s):  
Christopher Davies ◽  
Simon Slater ◽  
Christoper De Leon

Abstract For many years, pipeline safety regulations in the US have defined prescriptive minimum requirements for integrity management combined with a clear expectation that operators should do more than the minimum where appropriate. The regulations have also provided operators with the flexibility to take a performance based integrity management approach leveraging as much information available to manage threats effectively. One the threats that must be managed is Selective Seam Weld Corrosion (SSWC). SSWC is an environmentally assisted mechanism in which there is increased degree of metal loss in the longitudinal weld in comparison to the surrounding pipe body. An appropriate definition is linear corrosion that is deeper in the longitudinal weld zone than the surrounding pipe body. In some cases, the surrounding pipe body may have limited or no corrosion present, and in other cases the pipe body corrosion may have occurred but at a slower rate than the local corrosion in the longitudinal weld zone. Conventional responses to potential or identified threats focus on in-situ investigations, often resulting in expensive and un-planned repairs for features reported by In-line Inspection (ILI) that when assessed properly demonstrate a remnant life well into the next inspection interval. When ILI identifies metal loss indications co-located with the longitudinal seam weld, the current prescribed response is often a blanket call for remediation. Such a response may not be appropriate if an ILI system is deployed to discriminate feature types and integrity assessment is exercised leveraging a sound understanding of the pipe’s material properties. This paper describes an approach that can be taken to manage the threat of SSWC. The foundation of the approach is deployment of an appropriate ILI system incorporating an effective ILI technology, an optimized evaluation process considering the specific threat morphology, material testing and a structured dig program. The evaluation process uses the ILI data and data from the field in combination material properties data and a susceptibility analysis to classify anomalies as “Likely”, “Possible” and “Unlikely” SSWC. This is aligned with the guidance in API RP 1176 “Assessment and Management of Cracking in Pipelines” for defining an appropriate response to ILI calls. Approaching the management of SSWC in this way allows operators to define a structured response for excavation activities to verify the process and remediate features as required. By using likelihood classification the risk to pipeline integrity can be reduced by acting on the most likely SSWC features as a priority, whilst collecting the data needed to make informed decisions on where to focus resources and efforts on what is a very complicated and difficult to manage threat. The output form this work, including a future plan for managing the remaining metal loss features, can be documented in a procedure and incorporated into an existing Integrity Management Plan.


Author(s):  
Shailesh Javia

Integrity management of pipelines is a systematic, comprehensive and integrated approach to proactively counter the threats to pipeline integrity. Pressure testing, in-line inspection and direct assessment methods are used to verify the integrity of a buried pipeline. The Paper Discuses Direct Assessment Methodologies for Hydrocarbon Non Piggable Pipelines. Advantages and Disadvantages of Direct Assessment methodology and DA Protocols. The DA process accomplishes this by utilizing and integrating condition monitoring, effective mitigation, meticulous documentation and timely structured reporting processes. DA is a structured, iterative integrity assessment process through which an operator may be able to assess and evaluate the integrity of a pipeline segment. TIME DEPENDENT THREATS INEVITABLY LED TO NUMEROUS FAILURES WITH A COMMON DEFINING MECHANISM OR SOURCE – CORROSION. This Paper will focus on internal, external and stress corrosion cracking direct assessment along with pre and post assessment, quality assurance, data analysis and integration, and remediation and mitigation activities. This paper will discuss some of the regulatory requirements for Pipeline Integrity Management System.


2021 ◽  
Author(s):  
Biramarta Isnadi ◽  
Luong Ann Lee ◽  
Sok Mooi Ng ◽  
Ave Suhendra Suhaili ◽  
Quailid Rezza M Nasir ◽  
...  

Abstract The objective of this paper is to demonstrate the best practices of Topside Structural Integrity Management for an aging fleet of more than 200 platforms with about 60% of which has exceeded the design life. PETRONAS as the operator, has established a Topside Structural Integrity Management (SIM) strategy to demonstrate fitness of the offshore topside structures through a hybrid philosophy of time-based inspection with risk-based maintenance, which is in compliance to API RP2SIM (2014) inspection requirements. This paper shares the data management, methodology, challenges and value creation of this strategy. The SIM process adopted in this work is in compliance with industry standards API RP2SIM, focusing on Data-Evaluation-Strategy-Program processes. The operator HSE Risk Matrix is adopted in risk ranking of the topside structures. The main elements considered in developing the risk ranking of the topside structures are the design and assessment compliance, inspection compliance and maintenance compliance. Effective methodology to register asset and inspection data capture was developed to expedite the readiness of Topside SIM for a large aging fleet. The Topside SIM is being codified in the operator web-based tool, Structural Integrity Compliance System (SICS). Identifying major hazards for topside structures were primarily achieved via data trending post implementation of Topside SIM. It was then concluded that metal loss as the major threat. Further study on effect of metal loss provides a strong basis to move from time-based maintenance towards risk-based maintenance. Risk ranking of the assets allow the operator to prioritize resources while managing the risk within ALARP level. Current technologies such as drone and mobile inspection tools are deployed to expedite inspection findings and reporting processes. The data from the mobile inspection tool is directly fed into the web based SICS to allow reclassification of asset risk and anomalies management.


Author(s):  
Terry Griffiths ◽  
Scott Draper ◽  
Liang Cheng ◽  
Feifei Tong ◽  
Antonino Fogliani ◽  
...  

As offshore renewable energy projects progress from concept demonstration to commercial-scale developments there is a need for improved approaches beyond conventional cable engineering design methods that have evolved from larger diameter pipelines for the oil and gas industry. New approaches are needed to capture the relevant physics for small diameter cables on rocky seabeds to reduce the costs and risks of power transmission and increase operational reliability. This paper reports on subsea cables that MeyGen installed for Phase 1a of the Pentland Firth Inner Sound tidal stream energy project. These cables are located on rocky seabeds in an area where severe metocean conditions occur. ROV field observation of these cables shows them to be stable on the seabed with little or no movement occurring over almost all of the cable routes, despite conventional engineering methods predicting significant dynamic movement. We cite recent research undertaken by the University of Western Australia (UWA) to more accurately assess the hydrodynamic forces and geotechnical interaction of cables on rocky seabeds. We quantify the conformity between the cables and the undulating rocky seabed, and the distributions of cable-seabed contact and spanning via simulations of the centimetric-scale seabed bathymetry. This analysis leads to calculated profiles of lift, drag and seabed friction along the cable, which show that all of these load and reaction components are modelled in an over-conservative way by conventional pipeline engineering techniques. Overall, our analysis highlights that current cable stability design can be unnecessarily conservative on rocky seabeds. Our work foreshadows a new design approach that offers more efficient cable design to reduce project capex and enhance through-life integrity management.


Author(s):  
Guy Desjardins ◽  
Joel Falk ◽  
Vitaly Vorontsov

While In-line Inspection Magnetic Flux Leakage (MFL) tools have been used for many years to successfully manage corrosion related threats, small pinhole-sized metal-loss anomalies remain a significant concern to pipeline operators. These anomalies can grow undetected to develop leaks and cause significant consequences. The physical dimensions of these anomalies, their proximity to and/or interaction with other nearby anomalies can challenge MFL’s detection and sizing capabilities. Other factors such as tool speed, cleanliness of the line and incorrect assumptions have an impact as well. For pipeline operators to develop effective and efficient mitigation programs and to estimate risks to an asset, the underlying uncertainties in detection and sizing of pinholes need to be well understood. By using magnetic modeling software, the MFL response of metal-loss anomalies can be determined, and the effect of a number of factors such as radial position, wall thickness, depth profile, pipe cleanliness and tool speed on MFL response and reporting accuracy can be determined. This paper investigates these factors to determine the leading causes of uncertainties involved in the detection and sizing of pinhole corrosion. The understanding of these uncertainties should lead to improvements in integrity management of pinhole for pipeline operators. This paper first investigates the physical measurement methodology of MFL tools to understand the limitations of MFL technology. Then, comparisons of actual MFL data with field excavation results were studied, to understand the limitations of specific MFL technologies. Finally, recommendations are made on how to better use and assess MFL results.


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