An Update to the UKOPA Pipeline Damage Distributions

2012 ◽  
Author(s):  
Graham Goodfellow ◽  
Susannah Turner ◽  
Jane Haswell ◽  
Richard Espiner
Keyword(s):  
Failure Rate ◽  
Structural Reliability ◽  
Operating Experience ◽  
Quantitative Risk Assessment ◽  
External Interference ◽  
Failure Frequency ◽  
Product Loss ◽  
Distribution Parameters ◽  
Transmission Pipeline ◽  
Incident Rates

The United Kingdom Onshore Pipeline Operators Association (UKOPA) was formed by UK pipeline operators to provide a common forum for representing operators interests in the safe management of pipelines. This includes providing historical failure statistics for use in pipeline quantitative risk assessment and UKOPA maintain a database to record this data. The UKOPA database holds data on product loss failures of UK major accident hazard pipelines from 1962 onwards and currently has a total length of 22,370 km of pipelines reporting. Overall exposure from 1952 to 2010 is of over 785,000 km years of operating experience with a total of 184 product loss incidents during this period. The low number of failures means that the historical failure rate for pipelines of some specific diameters, wall thicknesses and material grades is zero or statistically insignificant. It is unreasonable to assume that the failure rate for these pipelines is actually zero. However, unlike the European Gas Incident data Group (EGIG) database, which also includes the UK gas transmission pipeline data, the UKOPA database contains extensive data on measured part wall damage that did not cause product loss. The data on damage to pipelines caused by external interference can be assessed to derive statistical distribution parameters describing the expected gouge length, gouge depth and dent depth resulting from an incident. Overall 3rd party interference incident rates for different class locations can also be determined. These distributions and incident rates can be used in structural reliability based techniques to predict the failure frequency due to 3rd party damage for a given set of pipeline parameters. The UKOPA recommended methodology for the assessment of pipeline failure frequency due to 3rd party damage is implemented in the FFREQ software. The distributions of 3rd party damage currently used in FFREQ date from the mid-1990s. This paper describes the work involved in updating the analysis of the damage database and presents the updated distribution parameters. A comparison of predictions using the old and new distributions is also presented.

An Update to the Recommended UKOPA External Interference Frequency Prediction Model and Pipeline Damage Distributions

2018 ◽  
Author(s):  
Graham Goodfellow ◽  
Chris Lyons ◽  
Susannah Turner ◽  
Fraser Gray ◽  
Simon Joyce
Keyword(s):  
Failure Rate ◽  
Structural Reliability ◽  
Operating Experience ◽  
External Interference ◽  
Failure Frequency ◽  
Depth Analysis ◽  
Product Loss ◽  
Distribution Parameters ◽  
The Uk ◽  
Incident Rates

The United Kingdom Onshore Pipeline Operators Association (UKOPA) was formed by UK pipeline operators to provide a common forum for representing operators interests in the safe management of pipelines. This includes providing historical failure statistics for use in pipeline quantitative risk assessment and UKOPA maintain a database to record this data. The UKOPA database holds data on product loss failures of UK major accident hazard pipelines from 1962 onwards and currently has a total length of 21,845 km of pipelines reporting. Overall exposure from 1952 to 2016 is 927,351 km years of operating experience with a total of 197 product loss incidents since 1962. The low number of failures means that the historical failure rate for pipelines of some specific diameters, wall thicknesses and material grades is zero or statistically insignificant. It is unreasonable to assume that the failure rate for these pipelines is actually zero. In addition to product loss incidents, the UKOPA database contains extensive data on measured part wall damage that did not cause product loss, unlike the European Gas Incident data Group (EGIG) database, which also includes the UK gas transmission pipeline product loss data. The data on damage to pipelines caused by external interference can be assessed to derive statistical distribution parameters describing the expected gouge and dent dimensions resulting from an incident. Overall external interference incident rates for different class locations can also be determined. These distributions and incident rates can be used in structural reliability based techniques to predict the failure frequency due to external interference for a given set of pipeline parameters. The current distributions of external interference damage were derived from data up to 2009 and presented as Weibull distributions for gouge depth, gouge length and dent depth. Analysis undertaken for the COOLTRANS CO2 pipeline project, undertaken by National Grid in the UK, has identified several improvements to the recommended UKOPA approach to external interference failure frequency prediction. This paper summarises those improvements and presents updated damage distribution parameters from data up to 2016.

Revision to the UK Pipeline Quantitative Risk Assessment Guidelines IGEM/TD/2 and PD 8010-3

2014 ◽  
Author(s):  
Graham D. Goodfellow ◽  
Jane V. Haswell ◽  
Neil W. Jackson ◽  
Roger Ellis
Keyword(s):  
Risk Assessment ◽  
Land Use ◽  
Land Use Planning ◽  
Best Practice ◽  
Research Work ◽  
Quantitative Risk Assessment ◽  
External Interference ◽  
Common View ◽  
Failure Frequency ◽  
The Uk

The United Kingdom Onshore Pipeline Operators Association (UKOPA) was formed by UK pipeline operators to provide a common forum for representing pipeline operators interests in the safe management of pipelines. This includes ensuring that UK pipeline codes include best practice, and that there is a common view in terms of compliance with these codes. Quantitative risk assessment (QRA) is used by operators in the UK to determine if individual and societal risk levels at new developments adjacent to existing pipelines are as low as reasonably practicable (ALARP). In 2008 the UKOPA Risk Assessment Working Group developed codified advice on the use of QRA applied to land use planning assessments, which was published by the Institution of Gas Engineers & Managers (IGEM) and the British Standards Institute (BSI). This advice was designed to ensure a standard and consistent approach, and reduce the potential for disagreement between stakeholders on the acceptability of proposed developments. Since publication of IGEM/TD/2 and PD8010-3 in 2008, feedback from users of the guidance together with new research work and additional discussions with the UK safety regulator, the Health & Safety Executive (HSE), have been undertaken and the codified advice has been revised and reissued in June 2013. This paper describes the revisions to the guidance given in these codes in relation to: • Clarification on application • Update of physical risk mitigation measures (slabbing and depth of cover) • Update of HSE approach to Land Use Planning • Update of failure frequency data: ○ Weibull damage distributions for external interference ○ Generic failure frequency curve for external interference ○ Prediction of failure frequency due to landsliding The revised codes, and their content, are considered to represent the current UK best practice in pipeline QRA.

A Methodology for the Prediction of Pipeline Failure Frequency Due to External Interference

2008 ◽  
Author(s):  
C. Lyons ◽  
J. V. Haswell ◽  
P. Hopkins ◽  
R. Ellis ◽  
N. Jackson
Keyword(s):  
Damage Mechanism ◽  
External Interference ◽  
Gas Industry ◽  
Failure Frequency ◽  
Failure Data ◽  
Mechanics Model ◽  
The United Kingdom ◽  
Pipeline Failure ◽  
The Uk ◽  
Operational Failure

The United Kingdom Onshore Pipeline Operators Association (UKOPA) is developing supplements to the UK pipeline codes BSI PD 8010 and IGE/TD/1. These supplements will provide a standardized approach for the application of quantified risk assessment to pipelines. UKOPA has evaluated and recommended a methodology: this paper covers the background to, and justification of, this methodology. The most relevant damage mechanism which results in pipeline failure is external interference. Interference produces a gouge, dent or a dent-gouge. This paper describes the fracture mechanics model used to predict the probability failure of pipelines containing dent and gouge damage and contains predictions of failure frequency obtained using the gas industry failure frequency prediction methodologies FFREQ and operational failure data from the UKOPA fault database. The failure model and prediction methodology are explained and typical results are presented and discussed.

scholarly journals Neglect Of Parameter Estimation Uncertainty Can Significantly Overestimate Structural Reliability

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Árpád Rózsás ◽  
Miroslav Sýkora
Keyword(s):  
Parameter Estimation ◽  
Bayesian Statistics ◽  
Failure Probability ◽  
Structural Reliability ◽  
Probabilistic Models ◽  
Estimation Uncertainty ◽  
Point Estimates ◽  
Distribution Parameters ◽  
Order Of Magnitude ◽  
Parameter Estimation Uncertainty

Abstract Parameter estimation uncertainty is often neglected in reliability studies, i.e. point estimates of distribution parameters are used for representative fractiles, and in probabilistic models. A numerical example examines the effect of this uncertainty on structural reliability using Bayesian statistics. The study reveals that the neglect of parameter estimation uncertainty might lead to an order of magnitude underestimation of failure probability.

Vent Gas Collection From Gas Compressor Dry Gas Seals

2004 ◽  
Author(s):  
Ari Suomilammi
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Experience ◽  
Methane Emissions ◽  
Emissions Reduction ◽  
Transmission Pipeline ◽  
Reduce Emissions ◽  
Gas Seals ◽  
National Programs ◽  
Year 2000

Gasum is an importer of natural gas and is operating and maintaining the Finnish transmission pipeline in which the pressure is maintained with three compressor stations. Gasum’s compressor stations are unmanned and remotely controlled from the central control room. Some of the compressor units are equipped with dry gas seals. The otherwise satisfactory operation of dry gas seals has the disadvantage of methane emissions. Reduction of methane emissions has been stated as a target by international auspices of the Kyoto Protocol or through national programs seeking to reduce emissions. The application described in this paper to collect vent gases from the dry gas seals was installed into four of the compressor units during 2001. The compressors are centrifugal compressors: two of them are Nuovo Pignone PCL603 with PGT10DLE (10 MW) gas turbine and two are Demag DeLaval 2B-18/18 with Siemens Tornado gas turbines (6,5 MW). It is normal for dry gas seals to have a small leakage of gas through the seals due to the function principle and required cooling of the seals. This gas emitted from the seals is normally about of 5...10nm3/h per one compressor unit during operation and during the stand-still the leakage is almost zero. In the year 2000 the total amount of emitted gas in Gasum’s units was about 50.000 nm3 per four compressor units. The target was to find an efficient method to collect the dry gas seal vent gas and utilize it. The solution must be simple and its investment costs must be feasible. Injection of the vent gases to the gas turbine inlet air flow was selected as a solution among some alternatives. The operating experience so far has been several thousands of operating hours without any malfunctions. The amount of collected gas by this system has been in the range of 80.000 nm3 per annum. The total cost of the system for four compressor units was about 85.000€. The intention of this paper is not to describe any scientific approach to the issue but to present a practical solution with operating experience.

scholarly journals MARSplines method as a tool for failure frequency modelling

2018 ◽  
Vol 44 ◽  
pp. 00086
Author(s):  
Małgorzata Kutyłowska
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Failure Rate ◽  
Basis Function ◽  
Adaptive Algorithm ◽  
Point Of View ◽  
Water Utility ◽  
Failure Frequency ◽  
Rate Prediction ◽  
Operational Data

The paper presents the results of failure rate prediction using adaptive algorithm MARSplines. This method could be defined as segmental and multiple linear regression. The range of segments defines the range of applicability of that methodology. On the basis of operational data received from Water Utility two separate models were created for distribution pipes and house connections. The calculations were carried out in the programme Statistica 13.1. Maximal number of basis function was equalled to 30; so-called pruning was used. Interaction level equalled to 1, the penalty for adding basis function amounted to 2, and the threshold – 0.0005. GCV error equalled to 0.0018 and 0.0253 as well as 0.0738 and 0.1058 for distribution pipes and house connections in learning and prognosis process, respectively. The prediction results in validation step were not satisfactory in relation to distribution pipes, because constant value of failure rate was observed. Concerning house connections, the forecasting was slightly better, but still the overestimation seems to be unacceptable from engineering point of view.

Reduction Factors for Estimating the Probability of Failure of Mechanical Damage Due to External Interference

2008 ◽  
Author(s):  
Andrew Cosham ◽  
Jane Haswell ◽  
Neil Jackson
Keyword(s):  
Structural Reliability ◽  
Historical Data ◽  
Mechanical Damage ◽  
Probability Of Failure ◽  
Risk Assessments ◽  
External Interference ◽  
Failure Data ◽  
Major Accident ◽  
The Uk ◽  
Reduction Factors

Quantified risk assessments (QRAs) are widely used in the UK to assess the significance of the risk posed by major accident hazard pipelines on the population and infrastructure in the vicinity of the pipeline. A QRA requires the calculation of the frequency of failures and the consequences of failures. One of the main causes of failures in onshore pipelines is mechanical damage due to external interference, such as a dent, a gouge, or a dent and gouge. In the published literature, two methods have been used to calculate the probability of failure due to external interference: • historical failure data and • limit state functions combined with historical data (i.e. structural reliability-based methods). Structural reliability-based methods are mathematically complicated, compared to using historical failure data, but have several advantages, e.g. extrapolation beyond the limited historical data, and the identification of trends that may not be apparent in the historical data. In view of this complexity, proposed supplements to the UK pipeline design codes IGE/TD/1 (natural gas) and PD 8010 (all substances) — on the application of QRAs to proposed developments in the vicinity of major accident hazard pipelines — include simple ‘reduction factors’ for use in ‘screening’ risk assessments. These ‘reduction factors’ are based on a comprehensive parametric study using a structural reliability-based model to calculate the probability of failure due to mechanical damage, defined as: gouges, and dents and gouges. The two ‘reduction factors’ are expressed in terms of the design factor and wall thickness of the pipeline. It is shown that, through appropriate normalisation, the effects of diameter, grade and toughness are secondary. Reasonably accurate, but conservative, estimates of the probability of failure can be obtained using these ‘reduction factors’. The proposed methodology is considerably simpler than a structural reliability-based analysis. The development and verification of these ‘reduction factors’ is described in this paper.

Assessment of Aging of Nuclear Power Plant Civil Structures

2002 ◽  
Author(s):  
D. J. Naus ◽  
B. R. Ellingwood ◽  
H. L. Graves
Keyword(s):  
Reinforced Concrete ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Structural Reliability ◽  
Operating Experience ◽  
Assessment Tools ◽  
Background Information ◽  
Civil Structures ◽  
Age Related

Research is being conducted by ORNL for the USNRC to address aging of civil structures in light-water reactor plants. The importance and operating experience of nuclear power plant (NPP) civil structures is reviewed. Factors that can lead to age-related degradation of reinforced concrete structures and containment metallic pressure boundaries (i.e., steel containments and liners of reinforced concrete containments) are identified and their manifestations described. Background information and data for improving and developing methods to assess the effects of age-related degradation on structural performance are provided. Techniques for detection of degradation are reviewed and research related to development of methods for inspection of inaccessible regions of the containment pressure boundary presented. Application of structural reliability analysis methods to develop condition assessment tools and guidelines is described.

A Structural Reliability Approach to Management of Defective Spiral Welding in a ‘Legacy’ Pipeline

2010 ◽  
Author(s):  
Michael Gardiner ◽  
Ross Michie ◽  
Gerardo Douce
Keyword(s):  
Structural Reliability ◽  
Buenos Aires ◽  
Limit State ◽  
State Function ◽  
Operating Pressure ◽  
Limit State Function ◽  
Line Pipe ◽  
Failure Frequency ◽  
Failure Point ◽  
Weld Root

Metrogas SA operates a natural gas distribution concession within the Greater Buenos Aires region of Argentina. In August 2007 a failure occurred on a section of the 22-bar system that dates from the early 1960s and, as such, was ‘inherited’ by Metrogas at privatization. The line pipe in this part of the system is spirally welded and at the failure point the spiral weld root was found to have been incomplete. Subsequent investigations showed that incomplete spiral welds were also present at other locations in the same section of the system. This paper describes some of the steps taken to investigate the incident of 2007 and to manage the threat from other defective spiral welds in the same pipeline section. We present a limit state model for through-wall failure of such features and show how this was used to help understand the incident. We also discuss modeling of uncertainties in parameters of the model and look at results from a probabilistic structural reliability implementation of the limit state function, which allowed the failure frequency of other defective spiral welds in this section to be predicted for various reductions of the operating pressure. Metrogas was then able to use these quantified reliability data to make a responsible, informed decision to keep the affected section in downrated service.

Failure Frequency Calculation of Transmission Pipelines or Stations due to Nearby Wind Turbines

2016 ◽  
Author(s):  
Roelof P. Coster ◽  
Martijn T. Middel ◽  
Marc T. Dröge
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Failure Modes ◽  
Software Tool ◽  
Failure Criteria ◽  
Risk Assessments ◽  
Failure Frequency ◽  
Risk Zoning ◽  
Transmission Pipeline ◽  
Transmission Pipelines

The present article discusses the methodology to include potential wind turbine failures in quantified risk assessments (QRA) of transmission pipelines or stations, which is included in the latest version of the Dutch national ‘Handbook on Risk Zoning of Wind Turbines’ (‘Handboek Risicozonering Windturbines’) [1]. The methodology includes a simple set of wind turbine failure modes and frequencies, probability density functions and failure criteria of the impacted underground pipeline or aboveground station components. Using the methodology, an additional failure frequency can be calculated for a transmission pipeline or a station due to the presence of one or several wind turbines. The focus of the methodology is not on the physics of each of the separate scenarios (many different studies and approaches are publically available), but as a practical tool for quantified risk assessments and determination of acceptable siting distances for wind turbines near gas infrastructure. The pressure and the (possibly non-uniform) construction parameters and depth of cover of underground pipelines are taken into account in the calculations. The methodology shown in this article was developed by DNV GL and published in Netherlands Enterprise Agency’s ‘Handbook on Risk Zoning of Wind Turbines’ in May of 2013. Following the publication of this Handbook, a software tool has been developed to implement the calculation method. This software is also discussed in this article.

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