Pipeline operators sometimes face challenges in finding an optimum decision while executing both capital and operational projects. Utility- and risk-based decision-making approaches could create a framework for devising an optimum solution, especially in cases involving multi-parameter decision making. From a utility function perspective, an optimum solution would be the one with the least amount of cost and the highest benefit. In other words, an optimum solution could be achieved by maximizing a utility function. Accordingly, as an optimization problem, constraints related to safety, risk, and reliability for a given scenario could limit or dictate the space of feasible solutions. Addressing the problem of arriving at an optimum solution for a multi-parameter decision is the core topic of this paper. Moreover, optimized utility functions — decision making analyses based on probabilistic risk assessment — are discussed. In addition, the paper introduces a conceptual approach that has been utilized for infrastructure decision making: the life quality index (LQI) approach.

Trans Mountain Pipe Line Company Ltd. (TMPL) owns and operates an 1146 km NPS 24 low vapor pressure petroleum products pipeline between Edmonton, Alberta and Burnaby, British Columbia. In 1998 TMPL retained BGC Engineering Inc. (BGC) to start a three-phase geotechnical and hydrotechnical hazard assessment of the right of way (ROW) from Hinton, Alberta to Kamloops, British Columbia. As part of this work GroundControl was asked to develop an electronic database with which to capture the information generated by BGC during the hazard assessment work. This paper describes the development and evolution of the database application that accompanied the study to quantitatively assess and prioritize the geotechnical and hydrotechnical hazard potential along the pipeline. This paper describes how the database provides TMPL employees across British Columbia and Alberta access to the current results of the hazard assessment plus supporting information such as multi-temporal images and internal and 3rd party reports about the pipeline. The purpose of the database and the unique architecture and functionality that accommodates ongoing monitoring and inspections of slopes and stream crossings is provided. Database security, access, and information sharing unique to TMPL are also described. Benefits and costs of the application plus technical and business challenges overcome by TMPL, BGC, and GroundControl are discussed. Recommendations from TMPL and GroundControl for similar information management initiatives are provided and future work is described. This paper is targeted to pipeline managers who are looking for economical, practical, and innovative information management solutions for managing their natural hazards.

Pipelines are the most economical way to transport hydrocarbons. In Mexico, PEMEX manages more than 60,000 Km of oil and gas land and marine pipelines. Therefore, their structural integrity must be carefully assessed. Pipeline managers require reliable and realistic codes in order to back up their decisions about design, maintenance and operation. In particular, for safety prediction, the failure modes and uncertainties involved in each loading condition need to be incorporated in the analysis in order to specify the pipelines use thresholds that keep them over acceptable safety levels within their operating lifetimes [1, 2]. For these reasons, a structural reliability formulation appears to be the appropriate framework to perform the evaluation. In this paper, the land pipeline reliability is estimated for the internal pressure, bending and tension failure mode conditions. These loading conditions are applied individually and tension and bending in a combined fashion, and random variability on the internal pressure, steel mechanical properties as well as the degradation effect of internal corrosion due to the transported fluid is included. So far, seamless pipeline is considered as used in Mexico. A set of internal pressures and mechanical properties are randomly generated through Monte Carlo simulation and the pipeline response under each simulated condition is obtained by making use of commercial software. The response analysis resorts on the nonlinear finite element method and it involves the calculation of maximum stresses and stress concentration factors under no corroded and corroded conditions. The following limit states are assessed: 1) the margin between maximum stresses due to internal pressure, tension and bending and the material capacity and 2) the margin between stress concentration factor and fracture initiation toughness. The above described limit states are calculated for no corroded condition and, once the critical failure modes are identified, corrosion effect is included on them. The failure probability is estimated from the response statistics for the considered limit state. The Cornell reliability index and the respective safety factor are also estimated. These results may be further extended and used for risk assessments and code calibration for design, inspection and maintenance of pipelines in Mexico.

The quantitative risk assessment tool was used to calculate the failure rates, failure consequences and risk levels along the pipeline. Safety risk was characterized by the individual risk ratio, which was defined as the maximum individual risk associated with a given segment divided by the tolerable individual risk. Tolerable individual risk values were defined as a function of population density following the approach developed by MIACC and the UK HSE. Financial risk was expressed in dollars per km-year and included a dollar equivalent for public perception. The recommended maintenance plan was defined as the minimum cost option that achieved a tolerable safety risk. The first step in developing the plan was to identify all segments that do not meet tolerable risk criteria (i.e., segments with an individual risk ratio greater than 1). For each of these segments a number of potential maintenance scenarios that address the dominant failure threats were selected. A cost optimization analysis was then carried out in which the total expected cost associated with each maintenance option was calculated as the sum of implementing the option plus the corresponding financial risk component, amortized over the inspection interval. This analysis was used to identify the minimum cost alternative that meets the individual risk constraint. Outcomes of the analysis included the best maintenance option (e.g., inline inspection, hydrostatic test) and the optimal time interval for segment re-evaluation.

Aerial photograph interpretation is an accurate and economical method of assessing terrain conditions and natural hazards affecting pipelines and other linear facilities. Completed in advance of vehicle and helicopter-based reconnaissance, it provides a comprehensive site overview that cannot be obtained at ground level. Aerial photograph interpretation helps construct and confirm preliminary hazard and stream-crossing inventories, understand hazard mechanisms, and estimate hazard volume and activity. Time series photo interpretation uses several sets of aerial photographs taken of the same area in different years to track changes in terrain, stream patterns and land-use over time. In addition, aerial photographs are superior navigation tools in the field. These points are illustrated using examples from pipelines in British Columbia and Alberta. This work will be of interest to managers of pipelines throughout western Canada, and to those involved with pipeline route selection through mountainous regions.

Terasen Pipelines (Terasen) owns and operates an 1146 km low vapour pressure petroleum products pipeline between Edmonton, Alberta and Burnaby, British Columbia. Its right-of-way passes through some of the most geotechnically, hydrotechnically, and environmentally challenging terrain in Western Canada. This paper describes the latest advancement of a natural hazards and risk management database application that has supported a 6-year hazard management program to quantitatively assess and prioritize the geotechnical and hydrotechnical risk along the pipeline. This database was first reported at IPC 2002 in a paper entitled “Natural hazard database application — A tool for pipeline decision makers” [1]. This second paper describes the advancements since then, including the addition of the Hydrotechnical Field Inspection Module (FIM), an add-on tool that allows field inspection observations to adjust hazard and vulnerability. This paper discusses the challenges in building a methodology that is practical enough for field maintenance personnel to use yet sufficiently comprehensive to accurately describe improving or worsening hydrotechnical hazard conditions. Functionality to enter hazard inspection data, review inspection results in the office, and authorize changes to the hydrotechnical hazard probabilities are described in the paper and demonstrated in the conference presentation. The relationship between revised hazard, vulnerability, risk, and response thresholds (such as inspection frequency, monitoring, site surveys, or mitigation) are demonstrated using a river crossing with a dynamic hazard history. As in previous years, this paper is targeted to pipeline managers who are seeking a systematic hazard and risk management approach for their natural hazards.

TransGas undertook a risk-ranking project for storage facilities as the first step in the process of evaluating the financial and life-safety risk associated with the eight storage facilities that they operate in Saskatchewan, Canada. Based on this analysis, two salt cavern storage facilities were selected for a quantitative risk assessment. The most cost-effective maintenance actions for each cavern were determined as follows: Fault trees were prepared for all of the identified failure scenarios. Several unique computer models were developed to predict the failure rates of the events identified in the fault trees and the consequences associated with both sub-surface and atmospheric releases from the storage facilities. Both life-safety and financial risk were considered in the analysis. For each of the caverns, a number of potential maintenance scenarios were selected that address the dominant failure causes. Life-safety risk was assessed first and compared to the TransGas tolerance. A cost optimization analysis was then carried out in which the total expected future cost associated with each maintenance option was amortized over the benefit period and compared to the total expected future cost associated with the current maintenance practice. The paper describes the risk analysis and cost optimization approach and provides case study examples of the caverns analyzed and the recommendations reached in each case.