Critical Review of Risk Criteria for Natural Gas Pipelines

2016 ◽  
Author(s):  
Aleksandar Tomic ◽  
Shahani Kariyawasam
Keyword(s):  
Risk Assessment ◽  
Critical Review ◽  
Management Program ◽  
Quantitative Risk Assessment ◽  
Individual Risk ◽  
Relative Population ◽  
Natural Gas Pipelines ◽  
Risk Assessment Models ◽  
Risk Criterion ◽  
Integrity Management

Risk Assessment is an integral part of an Integrity Management Program (IMP), and it is generally the first step in most IMPs. Risk is of the product of two variables, the likelihood of failure and the consequence of failure, where failure is defined as a loss of containment event. Hence, it is necessary to calculate both variables in order to accurately model risk. To assess risk, criterion need to be established and the actual risk needs to be compared to the criterion in order to determine the acceptability of risk. Currently, most industry risk assessment models are qualitative risk models, where consequence is generally characterized by class, relative population measures, or some other relative measure. While this may be adequate for some relative risk ranking purposes, it is generally not accurate in representing the true consequences and the arbitrary nature leads to overly conservative or overly un-conservative results. Conversely, Quantitative Risk Assessment (QRA) models take into account the effect of the thermal radiation due to ignited pipeline rupture and evaluate the consequence on the surrounding human population. Such a consequence model is dependent on the pipeline properties (i.e. diameter and MOP) and the structure properties (i.e. precise locations and types of structures). The overall risk is then represented by two specific, well defined measures: Individual Risk (IR) and Societal Risk (SR). The goal of this paper is to perform a critical review of IR and SR acceptability criteria that are widely available and widely used, and outline the criteria (and the approach) adapted by TransCanada Pipelines. Worldwide, there are several different standards that define the criteria for evaluating IR and SR, particularly some countries with higher population densities around pipelines (e.g. UK and Netherlands). These IR and SR criteria have been compared in a hypothetical case study, to determine the most appropriate method in terms of the assumptions for calculating risks, the criteria, and how the actual risks compares to the criteria. The outcome of this study was the adoption of a defendable process for calculating SR, along with the associated criterion.

Effective Consequence Evaluation for System Wide Risk Assessment of Natural Gas Pipelines

2014 ◽  
Author(s):  
Aleksandar Tomic ◽  
Shahani Kariyawasam ◽  
Pauline Kwong
Keyword(s):  
Risk Assessment ◽  
Natural Gas ◽  
Management Program ◽  
Assessment Process ◽  
Individual Risk ◽  
Single Individual ◽  
Gas Pipelines ◽  
Risk Models ◽  
Relative Population ◽  
Natural Gas Pipelines

System Wide Risk Assessment (SWRA) is an integral part of an Integrity Management Program (IMP), and it is the first step in most IMPs. Risk is the expected value of loss (often expressed as damage per year, i.e. expected number of annual injuries or fatalities). Risk is calculated as the product of the Probability/Likelihood of Failure (LoF) and the consequence of failure, where failure is defined as a loss of containment event. Hence, it is necessary to calculate both the Likelihood and the consequences of failure in order to accurately model risk. For natural gas pipelines, consequence is primarily human safety-based. The primary threat to the population is the effect of the thermal radiation due to ignited pipeline ruptures. Currently, most pipeline industry system wide risk assessment models are qualitative risk models, where consequence is generally characterized by class, relative population measures, or some other relative measure. While this may be adequate for some relative risk ranking purposes, it is generally not accurate in representing the true consequences and the arbitrary nature leads to poor representation of actual consequences. Qualitative risk models are also highly subjective, and can have a high degree of bias. Thus, in this study, quantitative LoF assessment and a rigorous quantitative consequence model were used to make the risk assessment process more accurate, more objective, and transparent. The likelihood algorithm developed in this study is described in a companion paper. It should be noted that a quantitative estimate is never completely objective as subjective assumptions and idealizations are still involved, however it provides a framework to make it as objective as possible. The consequence model implemented in this study is highly quantitative, and it depends on the pipeline properties (i.e. diameter, MAOP etc.) in addition to the structure properties (i.e. precise location and type of structures). The lethality zone utilized in the consequence model is a curve which has 100% lethality at the point of rupture but recedes in lethality as the point of concern moves away from the rupture location. The lethality curve is calculated using the PIPESAFE software [6] that is developed by rigorous analytical, experimental, and verification work. This ensures that the lethality curves are pipeline specific. Furthermore, the position of the structures inside the lethality zones is taken into consideration, which means the structures located closer to the pipeline see a higher degree of lethality than the structures further away from the pipeline. Risk is represented by two specific, well defined measures: Individual Risk (IR), and Societal Risk (SR). These two measures are well accepted concepts of risk that go beyond the pipeline industry, and are particularly used in the pipeline industry in countries where quantitative risk is required by regulation (e.g. UK and Nederlands). IR takes into account the inherent risk of the pipeline to the single individual who may happen to be in the vicinity of the pipeline. SR, on the other hand, takes into account known population centers, settlements, and structures to define the risk to communities. When risk is calculated quantitatively, it is possible to use well defined and widely accepted criteria to determine the acceptability of risk in terms of IR and SR criteria for all pipelines. The advantages of using IR and SR are discussed and shown through implemented examples.

Layers of Bias: A Unified Approach for Understanding Problems With Risk Assessment

2018 ◽  
Vol 46 (2) ◽  
pp. 185-209 ◽  
Author(s):  
Laurel Eckhouse ◽  
Kristian Lum ◽  
Cynthia Conti-Cook ◽  
Julie Ciccolini
Keyword(s):  
Risk Assessment ◽  
Criminal Justice ◽  
Justice System ◽  
Quantitative Risk Assessment ◽  
Risk Scores ◽  
Risk Models ◽  
Risk Assessment Models ◽  
Final Layer ◽  
The Supreme Court ◽  
Using Data

Scholars in several fields, including quantitative methodologists, legal scholars, and theoretically oriented criminologists, have launched robust debates about the fairness of quantitative risk assessment. As the Supreme Court considers addressing constitutional questions on the issue, we propose a framework for understanding the relationships among these debates: layers of bias. In the top layer, we identify challenges to fairness within the risk-assessment models themselves. We explain types of statistical fairness and the tradeoffs between them. The second layer covers biases embedded in data. Using data from a racially biased criminal justice system can lead to unmeasurable biases in both risk scores and outcome measures. The final layer engages conceptual problems with risk models: Is it fair to make criminal justice decisions about individuals based on groups? We show that each layer depends on the layers below it: Without assurances about the foundational layers, the fairness of the top layers is irrelevant.

Quantitative Risk Assessment for Viral Contamination of Shellfish and Coastal Waters

1993 ◽  
Vol 56 (12) ◽  
pp. 1043-1050 ◽  
Author(s):  
JOAN B. ROSE ◽  
MARK D. SOBSEY
Keyword(s):  
Risk Assessment ◽  
Dose Response ◽  
Probability Model ◽  
Enteric Virus ◽  
Epidemiological Data ◽  
The United States ◽  
Hazard Identification ◽  
Quantitative Risk Assessment ◽  
Individual Risk ◽  
Viral Contamination

Human pathogenic viruses have been detected from approved shellfish harvesting waters based on the fecal coliform indicator. Until recently it was difficult to assess viral contamination and the potential impact on public health. Risk assessment is a valuable tool which can be used to estimate adverse effects associated with microbial hazards. This report describes the use of quantitative risk assessment for evaluating potential human health impacts associated with exposure to viral contamination of shellfish. The four fundamental steps used in a formal risk assessment are described within and include i) Hazard identification, ii) Dose-response determination, iii) Exposure assessment, and iv) Risk characterization. Dose-response models developed from human feeding studies were used to evaluate the risk of infection from contaminated shellfish. Of 58 pooled samples, 19% were found to be positive for viruses. Using an echovirus-12 probability model, the individual risk was determined for consumption of 60 g of raw shellfish. Individual risks ranged from 2.2 × 10−4 to 3.5 × 10−2. These data suggest that individuals consuming raw shellfish from approved waters in the United States may have on the average a 1 in 100 chance of becoming infected with an enteric virus. Using the rotavirus model which represents a more infectious virus, the risk rose to 5 in 10. The potential for use of a risk assessment approach for developing priorities and strategies for control of disease is immense. Epidemiological data have demonstrated the significance of shellfish-associated viral disease and, although limited, appropriate virus occurrence data are available. Additional information on virus occurrence and exposure is needed, and then scientific risk assessment can be used to better assure the safety of seafood.

Meeting the Geohazards Management Guidelines of Annex N

2010 ◽  
Author(s):  
Martin Zaleski ◽  
Tom Greaves ◽  
Jan Bracic
Keyword(s):  
Risk Assessment ◽  
Program Planning ◽  
Management Program ◽  
Hazard Identification ◽  
Government Agencies ◽  
Management Guidelines ◽  
Record Keeping ◽  
Reduction Program ◽  
Integrity Management

The Canadian Standards Association’s Publication Z662-07, Annex N provides guidelines for pipeline integrity management programs. Government agencies that regulate pipelines in Alberta, British Columbia and other Canadian jurisdictions are increasingly using Annex N as the standard to which pipeline operators are held. This paper describes the experience of Pembina Pipeline Corporation (Pembina) in implementing a geohazards management program to fulfill components of Annex N. Central to Pembina’s program is a ground-based inspection program that feeds a geohazards database designed to store geotechnical and hydrotechnical site information and provide relative rankings of geohazard sites across the pipeline network. This geohazard management program fulfills several aspects of the Annex, particularly: record keeping; hazard identification and assessment; risk assessment and reduction; program planning; inspections and monitoring; and mitigation. Pembina’s experience in growing their geohazard inventory from 65 known sites to over 1300 systematically inspected and catalogued sites in a span of approximately two years is discussed. Also presented are methods by which consultants and Pembina personnel contribute to the geohazard inspection program and geohazard inventory, and how the ground inspection observations trigger follow-up inspections, monitoring and mitigation activities.

scholarly journals Domain-specific risk assessment using integrated simulation: A case study of an onshore wind project

2021 ◽  
Author(s):  
Emad Mohamed ◽  
Nima Gerami Seresht ◽  
Stephen Hague ◽  
Adam Chehouri ◽  
Simaan M. AbouRizk
Keyword(s):  
Risk Assessment ◽  
Wind Farm ◽  
Critical Path ◽  
Quantitative Risk Assessment ◽  
Integrated Simulation ◽  
Domain Specific ◽  
Risk Assessment Models ◽  
First Case ◽  
Assessment Approach

Although many quantitative risk assessment models have been proposed in literature, their use in construction practice remain limited due to a lack of domain-specific models, tools, and application examples. This is especially true in wind farm construction, where the state-of-the-art integrated Monte Carlo simulation and critical path method (MCS-CPM) risk assessment approach has yet to be demonstrated. The present case study is the first reported application of the MCS-CPM method for risk assessment in wind farm construction and is the first case study to consider correlations between cost and schedule impacts of risk factors using copulas. MCS-CPM provided reasonable risk assessment results for a wind farm project, and its use in practice is recommended. Aimed at facilitating the practical application of quantitative risk assessment methods, this case study provides a much-needed analytical generalization of MCS-CPM, offering application examples, discussion of expected results, and recommendations to wind farm construction practitioners.

Technical safety: use of concept risk assessment for field development certainty

2019 ◽  
Vol 59 (2) ◽  
pp. 549
Author(s):  
Colin Crowley ◽  
Dave Ashton
Keyword(s):  
Risk Assessment ◽  
Design Feature ◽  
Safety Performance ◽  
Quantitative Risk Assessment ◽  
Individual Risk ◽  
Field Development ◽  
Risk Levels ◽  
Wide Range ◽  
Rule Sets ◽  
Risk Reduction Measures

As technology advances and field development possibilities grow, the need for earlier guidance on the safety performance of concept designs is greater than ever. The SNC-Lavalin concept risk assessment (CRA) tool is a transparent and rapidly deployable model that is based on sound, industry-accepted quantitative risk assessment (QRA) principles. From the earliest stages of field development, when conceptualisation may be vague and data sparse, a wide range and variety of design options can still be assessed effectively and ranked on their safety performance. The CRA tool is proprietary software initially developed with BP and Shell. The model was first calibrated against 10 detailed QRAs, but is regularly benchmarked and updated with the most current failure rate data and has been used on nearly 50 projects globally. The database now incorporates established rule sets from hundreds of detailed QRAs performed, including floating liquefied natural gas and floating storage regasification units. This paper presents a CRA case study for a generic remote offshore field with a range of development options from conventional to minimal offshore facilities. The model calculates the associated risks for the options considered and is presented in terms of individual risk per annum, temporary refuge impairment frequency and potential loss of life. The results highlight the effects of each individual design feature on risk levels by comparison of similar options side by side, noting the main risk contributors and allowing investigation of the benefits of risk reduction measures. This enables identification of the best design features from each of the options and allows an optimised design to be carried forward.

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