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Terms and Definitions
For the purposes of this document, the following terms and definitions apply
Leak detection system that is operating in real time or near real time.
NOTE It is usually SCADA-connected or uses continuous telemetry.
Ranking of the possible consequences of a leak based on a calculated value or a relative value of the consequences.
1 US Department of Transportation, 1200 New Jersey Ave SE, Washington DC 20590, www.dot.gov
Amount of hazardous liquid that is leaked after the onset of a leak prior to the shutdown of the pipeline (or other appropriate operational response is initiated).
NOTE This is also known as pumped volume.
Safeguards, including primary containment processes, equipment, engineered systems, operational procedures, management system elements, and worker capabilities, are essential for preventing loss of containment (LOC) and ensuring asset integrity These measures are designed to mitigate the potential consequences of process safety events.
3.1.5 externally based leak detection systems
Applications that use sensors to directly detect the presence of a hydrocarbon or physical changes in environment due to a leak.
NOTE 1 These sensors are placed on or near the external surface of the pipe or, in the case of cameras for instance, within sensing range of the pipeline.
NOTE 2 These sensors may be called leak detectors.
Psychological phenomenon that occurs within a group of people in which the desire for harmony or conformity in the group results in an irrational or dysfunctional decision-making outcome.
NOTE 1 Groupthink is often without critical evaluation of alternative viewpoints, actively suppresses dissenting viewpoints, and isolates the group from outside influences.
Groupthink can manifest through a diminished sense of vulnerability and complacency, creating an environment where the authority of the Pipeline Controller is overshadowed, ultimately hindering independent decision-making.
NOTE 3 NTSB has a number of publications related to this phenomenon under the topic Crew Resource Management.
That which may be a separate or complementary leak detection system that uses another technique, some verification method, separate calculations, leak detection specialists’ involvement, or other procedure or process.
3.1.8 internally based leak detection systems
Applications that are internally based using field sensor data that monitor internal (and perhaps related external) pipeline parameters but are not actually detecting the presence of hydrocarbons.
NOTE Since these systems do not actually contact leaked hazardous liquid, internally based leak detection systems may be regarded as inferential systems (see API 1130).
3.1.9 leak detection a) leak detection method
Classification of leak detection operation as being continuous or non-continuous. b) leak detection principle
Classification of leak detection by categories that are externally based or internally based. c) Leak Detection Program
The term "leak detection system" (LDS) refers to the comprehensive range of techniques utilized by pipeline operators to identify leaks This includes various methods for leak detection, as well as the associated policies, processes, and human factors involved in ensuring effective monitoring and response.
Individual technology applications (e.g real time transient model, wetted cable, fiber optical cable, etc.) used to actually detect or indicate a leak. e) Leak Detection System
End-to-end application of one technique that may be internally based or externally based and continuous or non- continuous. f) leak detection system (LDS) operational classifications
LDS designated by the pipeline operator as being the main primary LDS.
LDS that use a different technique, has different metrics, and, if possible, is independent of the inputs for the primary technique.
LDS that is used when the primary and complementary are out of service.
LDS that immediately takes over if the running LDS fails.
LDS that may be used to replace an LDS that has failed.
Alarm or other notifying event that suggests that present conditions indicate the possibility of a leak.
NOTE 1 The possibility of a leak is stronger if there is more than one indication.
NOTE 2 Industry also uses the word “triggers” for leak indications.
Form of pipeline leak detection that is intended to detect the occurrence of a leak smaller than a rupture.
The analysis of pipeline operations and conditions is essential when there is a suspicion of a leak This process aims to provide the necessary confidence to formally determine the presence or absence of a leak.
NOTE It may involve onsite investigation.
Unplanned or uncontrolled release of hazardous liquid to the environment.
In the industry, terms such as leak, spill, release, fluid release, or commodity release are often synonymous with a loss of containment (LOC) This phenomenon is also referred to as loss of primary containment (LOPC).
Performance category that is quantified by Key Performance Indicators (KPIs).
NOTE Leak detection metrics are well described in API 1130, Annex C and are grouped into four categories, or metrics, that determine a system's reliability, sensitivity, accuracy, and robustness.
Consequence level of an event after the escalation barriers have been evaluated.
Type of leak detection that is periodic but not in real time.
Total leak volume that occurs from the time the pipeline leak begins until all leakage is stopped.
NOTE It includes dynamic leak volume plus static leak volume.
Significant Incidents are defined as events that meet specific criteria, excluding Fire First incidents These include fatalities or injuries that necessitate inpatient hospitalization, incidents resulting in total costs of $50,000 or more (adjusted to 1984 U.S dollars), highly volatile liquid releases of 5 barrels or more, or other liquid releases of 50 barrels or more Additionally, any liquid releases that lead to an unintentional fire or explosion are also classified as significant incidents.
Amount of risk that the pipeline operator is willing to assume.
NOTE When the level of risk is above an acceptable level or is not tolerable it exceeds the risk tolerance.
The decision-making process focuses on prioritizing leak detection efforts by assessing calculated risks and comparing them to established risk tolerance levels, ultimately taking necessary actions to mitigate risks to an acceptable threshold.
Form of pipeline leak detection that is intended to swiftly detect the occurrence of a rupture.
NOTE 1 API/AOPL has produced a white paper called Liquid Pipeline Rupture Recognition and Response.
NOTE 2 What constitutes a rupture is determined on a pipeline by pipeline basis and defined by a pipeline operator.
Certain locations along the pipeline right-of-way (ROW), including but not limited to high consequence areas (HCAs) and urban settings (USAs), may experience significant adverse effects from leaks, impacting nearby individuals, the environment, and community resources.
NOTE See 49 CFR Part 195 for definition and description of HCAs and USAs
Amount of hazardous liquid that is leaked after the shutdown of the pipeline (or other appropriate operational response if applicable) is initiated.
NOTE This is known as drain-down volume.
Characteristic of a technology that has been in use for long enough that most of its initial faults and inherent problems have been removed or reduced by further development.
NOTE One of the key indicators of a mature technology is the ease of use for both non-experts and professionals.
Process where the function of the leak detection technique is adjusted for more precise functioning.
NOTE Tuning enhances alarm reliability by improving detection speed and adjusting leak detector settings, all while minimizing the occurrence of false alarms.
Consequence level of an event without the effect of escalation barriers or preventative and mitigation measures.
Acronyms and Abbreviations
For the purpose of this standard, the following abbreviated terms apply.
CMMS computerized maintenance management system
DfRM Design for Reliability and Maintainability
FMEA Failure Mode Effects Analysis
OJT on-the-job training
PHMSA US DOT Pipeline and Hazardous Materials Safety Administration
PPTS Pipeline Performance Tracking System
RACI Responsible, Accountable, Consulted, Informed
RAM Reliability, Availability, and Maintainability
This document outlines best practices for effectively managing a Company's pipeline Liquid Delivery Process (LDP), covering planning, selection, design, analysis, implementation, maintenance, and fostering a supportive culture Although it focuses on hazardous liquid pipelines regulated by CFR 49 Part 195, the principles can also be adapted for non-regulated pipelines.
In adopting the recommendations of API 1175, operators should progressively implement changes and establish a timeline for the associated work.
Effective pipeline leak detection requires the establishment of a comprehensive leak detection program (LDP) that integrates various elements A robust LDP fosters a strong leak detection culture, essential for addressing the human factors involved Additionally, the technical aspects of the LDP are guided by a well-defined leak detection strategy This document details the key components of an LDP.
— leak detection culture and strategy;
— selection of leak detection methods;
— performance targets, metrics, and KPIs;
— Control Center procedures for recognition and response;
— roles and responsibilities and training;
— reliability centered maintenance for leak detection equipment;
— overall performance evaluation of the LDP;
Figure 1 illustrates the LDP management process flow chart, highlighting the key elements outlined in API 1175 and their interconnections While this representation reflects the typical procedures for pipeline operators, it is not mandatory to adhere strictly to the depicted aspects.
5 Leak Detection Culture and Strategy
Leak Detection Culture
Culture within an organization reflects the behaviors of its members and the meanings they assign to those behaviors It is a collective attribute formed through interactions among individuals, leading to a shared understanding of values, morals, and decision-making processes Key elements of culture encompass the organization's vision, values, norms, systems, symbols, language, assumptions, and beliefs This dynamic attribute is shaped by both internal and external influences, with many cultural aspects learned through observation of others' actions Consistently performing tasks correctly is a cultural discipline that is ingrained through established operational principles.
Pipeline operators must cultivate a robust leak detection culture alongside their established safety culture A leak detection program (LDP) encompasses both the technology used and the personnel implementing it By enhancing the organization's culture, employees transition from merely considering safety and integrity to actively practicing them.
Leak detection culture is visible by the level of commitment of all employees, particularly an organization’s management Culture is defined and enhanced by ongoing management direction and support.
Effective leak detection requires collaboration among key organizational functions to succeed Fostering a robust leak detection culture that encourages swift responses can significantly mitigate the impacts of leaks.
The following behaviors are indicative of a strong leak detection culture.
— Visible ongoing management support for the LDP.
— A comprehensive leak detection strategy that is understood by all employees.
— Visible support for the LDP at all levels and sections of the organization.
— A goal to exceed the minimum leak detection requirements that are denoted by the regulations (see Figure 2).
— Ongoing support towards improving pipeline leak detection, even if the pipeline operator is meeting current leak detection goals.
Figure 1—Leak Detection Program Flow Diagram
— Specific evaluation of all methods of leak detection.
— Promotion and endorsement of teamwork within departments and across the organization.
— Coordination and collaboration between the different entities involved in the LDP.
— Well-developed internal communications strategies between groups who work in different areas (i.e field staff and Control Center staff) with different reporting structures.
— Clearly defined roles and responsibilities.
— Clear and concise policies, procedures, and processes in the Control Center and in other operations and maintenance activities.
— Comprehensive management of change process.
— Ongoing training of all staff regarding how each person supports leak detection.
— A focus on the safe and reliable operations of the pipeline with no negative repercussions on the staff who take actions in response to leak indications This includes:
— Stop-Work-Authority (SWA) or Stop-Work-Responsibility (SWR) Every employee has the authority and responsibility to stop unsafe work;
— Shutdown when there is a leak indication When in doubt, shut down and then assess; and
— Empowerment of the primary user, the Pipeline Controller, who has individual authority to promptly take action such as exercising SWA during leak indication events
Ongoing evaluation of culture is essential, utilizing employee surveys, feedback, and observational techniques to monitor its effectiveness Maintaining a record of these observations and recommendations is crucial for fostering a positive cultural environment.
Leak Detection Strategy
The pipeline operator must create and execute a comprehensive leak detection strategy that addresses all elements of the Leak Detection Program (LDP) This strategy will define the necessary requirements, establish the objectives of the LDP, and detail the methods by which the LDP will achieve these objectives.
A strategy outlines the approach to achieving goals through the effective use of resources Typically, the senior leadership of an organization is responsible for formulating this strategy It can be a deliberate plan or develop organically as the organization responds to its environment and competition Key components of strategy include strategic planning and strategic thinking.
The strategy should outline how the pipeline operator meets the pipeline’s specified minimum regulatory requirements (see 6.3.1) and may “go beyond” Going beyond may be any of:
— studying existing LDSs to determine how they may be improved,
— developing an LDP/LDS above minimum requirements,
— implementation of enhanced ROW surveillance,
— the use of more complex LDSs such as CPM,
— enhancements in the Control Center, and/or
— enhanced maintenance and sustainability requirements.
The strategy must be documented in a format that is managed and endorsed by leadership This documentation can take various forms, either as a single comprehensive document or as multiple documents that detail specific elements of the strategy It may address particular pipelines, product types, classified areas, or other components that necessitate enhancements to the overall strategy.
The essential elements of a pipeline operator's strategy include management commitment and leadership, clearly defined requirements and goals, and methods for satisfying those goals Additionally, employing risk management, selecting and integrating various Leak Detection Systems (LDSs), and adhering to regulatory requirements and industry standards are crucial Ongoing performance measurement of the Leak Detection Program (LDP), along with tuning, support, reporting, and comprehensive training, testing, and operational procedures, are also vital Furthermore, the strategy should encompass review and approval processes, effective change management, and a commitment to ongoing improvement of the LDP.
5.2.3 Details of the Essential Elements of the Strategy
A successful leak detection strategy requires strong management commitment and leadership, as evidenced by a comprehensive written strategy document This document should outline the roles and responsibilities of all employees and stakeholders involved in the pipeline operator's leak detection program (LDP) Management must demonstrate its dedication through resource allocation, visibility, and active leadership, fostering engagement at all organizational levels Additionally, there should be a focus on cultivating a culture that shifts from merely "thinking leak mitigation" to proactive leak prevention.
The leak detection strategy (LDP) should be endorsed by management and include clear goals for leak detection performance, ensuring alignment with daily operations It must cover all regulatory requirements and emphasize the importance of user confidence in leak alarms A detailed risk assessment should guide the LDP framework, integrating it with the integrity management program to address leak detection risks The selection of leak detection systems (LDS) should focus on proven methods, ensuring continuous monitoring and compliance with industry standards Regular performance evaluations and comparisons with industry best practices are essential, alongside a commitment to rigorous training for employees and stakeholders The strategy should facilitate ongoing improvements, adapting to regulatory changes and incorporating new technologies to enhance leak detection capabilities.
6 Selection of Leak Detection Methods
Selection Process Overview
Leak Detection Systems (LDS) are essential for early detection of loss of containment (LOC), enabling prompt actions to minimize leak consequences By reducing the time needed to identify a leak and initiate a shutdown, LDS effectively decreases the dynamic leak volume, allowing for better management of the static leak volume.
This section aims to assist pipeline operators in choosing the appropriate Leak Detection Systems (LDSs) and their corresponding principles, methods, and techniques for inclusion in their Leak Detection Plan (LDP) This selection process can be applied to new applications, the addition of extra LDSs, or the evaluation of current LDSs.
The selection of LDSs, leak detection principles, methods, and techniques is a multifaceted, multi-step, iterative process that involves at least the following elements:
— performing an overall risk assessment, usually through a leak detection-focused risk assessment;
— incorporating regulatory requirements, utilizing industry RPs (as warranted), and integrating the pipeline operator’s requirements;
— linking the pipeline operator’s performance metrics, KPIs, and targets;
— evaluating the best available technology for leak detection for the operator’s pipelines;
— designing the LDP through selection of the LDSs and associated principles, methods, techniques that become the pipeline operator’s LDP, including primary, complementary, and perhaps alternative LDSs;
— aligning the selection with the pipeline operator’s leak detection culture and strategy;
— modifying the selection to cover particular requirements of individual pipelines;
— evaluating the leak detection capability to ensure that the LDP covers all elements above;
— ensuring that the LDP has no gaps in certain, but infrequently occurring operating modes.
To validate the selection process of an existing LDP and ensure it aligns with best practices and requirements, this selection process can be applied effectively.
In any case, each facet or step of the selection process should be documented.
Risk Assessment
Risk assessment is a critical part of the LDS selection procedure The risk may be compared against the pipeline operator’s risk tolerance (see 6.2.2).
Leak detection systems (LDS) play a crucial role in minimizing the consequences of leaks, although they do not decrease the likelihood of such events Understanding and assessing the probability of leak occurrences, along with identifying potential threats and vulnerabilities, is essential for selecting appropriate leak detection solutions and designing effective leak detection plans (LDP).
The risk assessment must evaluate both the unmitigated and mitigated consequences of various leak rates at each pipeline location Additionally, it should assess the likelihood of these leak rates by analyzing the potential threats that could lead to their occurrence.
Annex A outlines the primary causes and threats of pipeline failures that can lead to leaks, highlighting that various initiating events have different probabilities of resulting in leaks of varying sizes The best sources for estimating potential leak sizes, volumes, and release scenarios are the historical data from pipeline operators and the industry It is crucial to understand that the worst-case leak scenario may not necessarily stem from the highest leak rate or potential volume Additionally, the effectiveness of certain leak detection technologies can vary based on the nature of the leak.
Estimating the likelihood of various leak rates is essential during risk analysis It's crucial to recognize that leak detection systems (LDSs) tend to be less reliable at lower leak rates and may require additional time for detection as the leak rate decreases.
An IMP risk analysis facilitates the evaluation of leak detection capabilities by providing a structured approach Operators should review this analysis to ensure that significant factors influencing the selection of leak detection principles, methods, and techniques are adequately considered While IMP risk analysis typically weighs likelihood and unmitigated consequences equally, leak detection risk analysis places greater emphasis on both unmitigated and mitigated consequences.
A thorough risk analysis and evaluation must assess the current operational elements of leak detection and prevention (LDP) to effectively mitigate leak consequences It is essential to examine integrity management activities alongside the characteristics of the pipeline segment to gauge the likelihood and impact of potential failures The risks linked to loss of containment (LOC) vary based on the type of pipeline, the hazardous liquids transported, and the specific location of the pipeline A targeted risk analysis, often referred to as a leak detection capability evaluation, can be conducted for each pipeline system or segment, in accordance with regulation 195.452(i)(3).
Several key factors influence the risk of loss of containment (LOC), including the leak's location, the type of material involved, the operational capacity to isolate and control flow, the quality of the LOC response program, and the effectiveness of leak prevention measures The consequences of leaks can vary significantly based on their location and the materials leaked.
49 CFR Part 195.452 (i)(3) promotes a risk-based methodology for assessing a pipeline operator's Leak Detection Program (LDP), emphasizing key factors essential for the selection process This approach necessitates a comprehensive evaluation of overall risk, consequences, and probabilities, allowing the operator to consider all three elements during the selection process.
In short, the risk factors in the LDS selection (see Annex A for expanded risk assessment evaluation points) are as follows
— Overall risk analysis of the pipeline.
— Review of the IMP, particularly the risk assessment results.
The review of the existing pipeline infrastructure involves assessing various critical factors, including the age and history of the pipes, the operating pressure compared to the hydro test ratio to determine safety margins, and the diameter, length, and size of the pipelines Additionally, it is essential to consider the type of hazardous liquids transported, the pipeline profile, and the identification of high-risk and consequence areas Furthermore, potential threats along the pipeline, ignition sources, and the specific terrain between the pipeline and high-consequence areas must be thoroughly evaluated to ensure safety and compliance.
— Review of known leak scenarios, history of leaks and their causes, an estimate of the likelihood of each scenario occurring, and, if possible, anticipate additional leak scenarios.
The isolation capability of a pipeline system is crucial, encompassing the types and locations of pumps and valves Current regulations mandate a risk assessment within the pipeline integrity management process, which includes an evaluation of valve operations alongside leak detection performance.
— Emergency response/leak response capability, including nearest locations of response personnel and time to respond.
— Leak detection capability of the existing LDSs:
— performance metrics: reliability, sensitivity, robustness, and accuracy;
— KPIs and evaluations of the LDSs;
— primary, complementary, alternative LDSs in place and their coverage.
— Leak detection capability of the existing LDP:
— strength of the leak detection culture;
— strength and completeness of the strategy.
— Leak size reduction initiatives and any IMP risk reduction initiatives:
Figure 2 illustrates the impact of cumulative risk scores on the selection of leak detection systems (LDSs) in a pipeline operator's leak detection strategy, with each vertical bar representing the risk score for different pipelines or pipe segments.
Pipelines with a high-risk score face greater consequences and an increased likelihood of failure, necessitating a leak detection strategy that exceeds the minimum regulatory requirements set by Part 195 These minimum standards include conducting surveillance patrols 26 times a year, ensuring no more than a three-week interval between inspections, implementing an in-line inspection program for detecting pipeline issues through methods such as pressure testing, hydro-testing, and smart-pigging, as well as maintaining public awareness programs.
The horizontal lines indicate the pipeline operator's chosen leak detection strategy based on specific risk levels The Leak Detection Plan (LDP) that aligns with the operator's requirements, as detailed in their strategy, is positioned above the minimum required leak detection line established by 49 CFR Part 195 This demonstrates that the selected leak detection strategy surpasses the risk level, ensuring a tolerable risk for the pipeline operation.
When a pipeline's risk surpasses the highest horizontal line, indicating the limits of the best leak detection available, operators may need to adjust the pipeline's operation, physical characteristics, or leak detection strategy Potential modifications include altering hydraulics, adjusting the maximum operating pressure (MOP), segmenting the pipeline with additional integrity meters, or implementing a more suitable leak detection method Additionally, operators may define the maximum duration for which the pipeline can operate above this risk threshold.
Implementing either minimum or enhanced leak detection comes with significant costs, as industry best practices for leak detection are expensive When choosing a leak detection strategy for a pipeline or its segments, it is essential to consider the practicality of the strategy in relation to the benefits of risk mitigation.
Incorporating Regulatory Requirements and RPs
The key regulatory standards for liquid pipelines are specified in 49 CFR Part 195 Operators must be fully aware of the leak detection protocols and associated requirements outlined in 49 CFR Part 195, as well as any additional regulations applicable to their pipelines.
Regulations outlined in 49 CFR Part 195 mandate minimum leak detection measures, which encompass landowner awareness through third-party reporting and regular inspections of right-of-way Additional requirements may involve smart pigging, pressure testing, and specific conditions for initial construction approval These essential leak detection protocols are illustrated in Figure 2 as Part 195 prescribed and minimum required measures.
Third-party reporting, as mandated by Part 195, is a crucial component of landowner awareness and serves as a type of leak detection system (LDS) Effective public awareness and coordination are essential for implementing this LDS in any region According to 49 CFR Part 195, minimum requirements outlined in section 195.440 include recommendations from API 1162 While the risk to individuals is lower in unpopulated areas, relying solely on third-party reporting for leak detection is less effective Therefore, it is vital for third parties present along the pipeline right-of-way (ROW) to be trained on what to observe and whom to contact in case of a leak.
The following code sections (with a brief description of contents) are applicable to liquid leak detection.
Section 195.134 mandates leak detection for hazardous liquid pipelines that transport liquid in a single phase, ensuring that each new CPM Leak Detection System (LDS) and any replaced components are compliant with safety regulations.
To effectively mitigate risk, the existing Continuous Pressure Monitoring Leak Detection System (CPM LDS) must adhere to Section 4.2 of API 1130 in its design, along with any additional design criteria specified in API 1130 for its components.
— Section 195.402, Procedural Manual for Operations, Maintenance, and Emergencies, contains a number of requirements that are applicable to leak detection and response such as:
— 195.402 (c)(2) requires procedures for gathering of data needed for reporting accidents;
According to regulation 195.402(c)(9), it is essential to implement procedures for identifying abnormal operating conditions by monitoring critical parameters such as pressure, temperature, and flow This data must be transmitted to a monitored location for facilities involved in the receipt or delivery of hazardous liquids.
— 195.402(e)(2) requires procedures for prompt and effective response to emergencies such as accidental leak of a hazardous liquid;
— 195.402(e)(4) requires procedures for taking action such as emergency shutdown to minimize volume leaked.
Section 195.412 mandates that pipeline operators conduct inspections of surface conditions on or near each pipeline right-of-way These inspections can be performed through various methods, including walking, driving, flying, or other suitable means Additionally, operators must assess the condition of each crossing beneath navigable waterways.
Section 195.444 mandates that all Continuous Pipeline Monitoring Leak Detection Systems (CPM LDS) installed on hazardous liquid pipelines, which transport liquid in a single phase, must adhere to API 1130 standards This compliance encompasses the operation, maintenance, testing, record-keeping, and training of dispatchers, also known as Pipeline Controllers, regarding the leak detection systems.
— Section 195.446, CRM has inherent requirements that help improve leak detection response for pipeline operators subject to the CRM regulations.
Section 195.452 mandates that pipeline operators implement leak detection systems in high-consequence areas to enhance safety and mitigate the impact of leaks This regulation emphasizes the importance of modifying and improving leak detection capabilities to protect sensitive areas along the pipeline.
According to 49 CFR 195.452(i)(3), pipeline operators must evaluate several critical factors, including the pipeline's length and size, the type of hazardous liquid being transported, its proximity to high-consequence areas, the speed of leak detection, the location of the nearest response personnel, leak history, and the results of risk analysis It is important to note that some of these factors may overlap with other selection criteria.
Additional details for hazardous liquid pipelines are:
— there may be special conditions or recommendations,
— in some cases, there may be a specific requirement for a specific LDS based on a contractual requirement where the pipeline operator operates a non-owned pipeline.
6.3.2 Recommended Practices, Standards, and Publications
There are a number of related RPs, standards, and publications These are noted in Section 2, Normative References Sources of additional information that may be useful are listed in the Bibliography.
Leak Detection Strategy Requirements
An effective leak detection strategy involves selecting leak detection systems (LDSs) that align with its specific goals and targets It is essential to understand these objectives during the selection process to ensure that both primary and complementary LDSs are incorporated appropriately.
The design and selection of leak detection systems must align with the pipeline operator's Level 1 to 4 KPIs The primary objective of a leak detection strategy is to ensure the timely identification of a leak of concern (LOC) from hazardous liquid pipelines, proportional to the associated risk level This strategy should include the necessary technology, processes, and trained personnel to swiftly recognize and respond to indications of a potential LOC.
To fulfill the strategy's requirements, operators can incorporate complementary and alternative leak detection systems (LDS) into the leak detection plan (LDP) The primary LDS, designated by the pipeline operator, is not rigidly defined, as its status can change based on operational conditions An LDS that is primary during normal operations may not hold that status during a pipeline shut-in, where another system might prove more reliable Typically, a continuous method is preferred as the primary LDS, with the continuous pipeline monitoring (CPM) technique often being the standard choice; however, an externally based LDS can also effectively meet the leak detection strategy.
A complementary LDS can be established as a continuous system that employs distinct techniques and metrics, ideally functioning independently from the primary technique's inputs Depending on the associated risks, multiple complementary LDS may be utilized within the pipeline system or selectively in specific segments when full implementation is impractical.
An alternative Leak Detection System (LDS) can be utilized when the primary system is unavailable Typically, this alternative LDS operates under strict supervision to ensure effective leak detection during pipeline operations.
Redundant LDSs are designated to ensure system reliability by mirroring the primary or complementary LDS, allowing for automatic fail-over in case of a failure These backup LDSs can be activated when needed, providing a seamless transition and maintaining system functionality.
Table 1 illustrates a Leak Detection Plan (LDP) that categorizes leak sizes, outlines potential Leak Detection Systems (LDS) for leak identification, and indicates a general timeframe for detecting Loss of Containment (LOC) Detailed definitions of the different leak sizes can be referenced in API 1130, Annex B.
Table 1—Visualization of an Example LDP
Leak Rate Rupture N/AMedium Leak O
Detection Probably O Detection Possible X Detection Improbable
List and Classification of LDSs
Leak detection systems (LDSs) utilize a diverse range of techniques, principles, and methods to identify leaks These techniques include surveillance, hydrocarbon sensors, and real-time monitoring software, with principles that can be either externally or internally based Additionally, the methods employed may be classified as continuous or non-continuous An example list of leak detection techniques is provided in Table 2, which categorizes them based on their internal or external basis and their continuous or non-continuous nature; however, it is not an exhaustive compilation of all available techniques.
Each practical Leak Detection System (LDS) has unique strengths and weaknesses influenced by its characteristics, the specific application, the leak detection technique used, its technological maturity, and the complexity of the pipeline Effectively applying the right LDS, in conjunction with established processes or procedures, is crucial for successful pipeline leak detection and prevention (LDP).
It is important to note the following when investigating the various techniques for leak detection.
— Additional instrumentation may need to be added to the pipeline to support a particular technique.
— Additional maintenance, support, and testing may be required for some techniques.
— Some existing techniques may be enhanced For example, the visual aspect of surveillance may be enhanced by the addition of infrared sensors.
Not all techniques in Table 2 have been validated, as some are still under evaluation for industrial applicability However, practical techniques are accessible, can be implemented by pipeline operators, and have demonstrated adequate field-based installation.
Table 2—List and Classification of LDSs
Ground-Based Line Surveillance Sniffer Tubes Hydraulic Calculations Hydro Testing Tracer Chemicals Pattern Recognition
Satellite Intelligent Pigs Shut-in Testing/Stand- up Testing
CP Monitoring Digital Signal Analysis
When evaluating an LDS, it is beneficial to consult with the vendor and other users about its application and anticipated performance However, it is important to recognize that each pipeline operation is distinct, which means the performance of the same LDS can differ greatly when applied to different pipelines.
For additional information on types of techniques, refer to the PRCI and NETL reports cited in the Bibliography.
Evaluating and Selecting Suitable Technologies
Following a thorough assessment of risk, pipeline operator strategies, and regulatory obligations, it is essential for operators to establish a selection criteria list for choosing Leak Detection Systems (LDSs) This process focuses on three critical aspects: identifying necessary features, determining required performance levels, and outlining the selection criteria for evaluating potential LDS options.
Selection factors for Liquid Distribution Systems (LDSs) are detailed in API 1130 Section 4.2 and Annex B, primarily focusing on Continuous Process Measurement (CPM) LDSs, though many factors are relevant to other non-CPM techniques as well Additionally, various other LDSs are commonly utilized in operations, including over/short calculations and SCADA monitoring and trending, alongside automated systems like meter-to-meter balancing.
The leak detection techniques that meet regulatory requirements are somewhat prescribed by the regulations or committed to by, for example, special permits, corrective action orders, or safety orders.
When choosing the Leak Detection System (LDS) for the Leak Detection Program (LDP), pipeline operators must be aware of the inherent limitations of the LDS that may affect its efficiency in quickly and accurately identifying leaks It is essential to measure performance using specific metrics and key performance indicators (KPIs).
The pipeline operator can categorize the LDS options into three distinct levels: regulatory level LDSs as per Part 195, best practices level LDSs following API 1175 guidelines, and green-field level LDSs that incorporate innovative technologies.
When selecting leak detection methods, various factors related to the physical environment and the hazardous liquids being transported must be considered Key elements include the elevation profile, nearby waterways such as rivers and lakes, major thoroughfares, spans and bridges, the properties of the fluids, site limitations, meteorological conditions, and the effects of radiant heat.
Choosing a Long-Distance System (LDS) is a significant long-term decision that involves both capital and operational expenditures The selection process should assess the entire life cycle impact, considering ancillary benefits like fiber optic networks for pipeline communications, public address and general alarm systems, closed-circuit television, and private automatic branch exchanges Additionally, public benefits, such as leasing spare lines to telecom companies for high-speed internet access in remote areas, should be evaluated Operators must consider both tangible and ancillary benefits, as these factors can influence life cycle calculations and the likelihood of obtaining necessary approvals.
When designing a Layered Defense Plan (LDP), it is crucial to adopt a holistic perspective, acknowledging that each component interacts with others to achieve optimal performance Various components serve distinct functions in reducing overall consequences An example of different categories of Layered Defense Systems (LDSs) based on their time frame is presented in Table 1 The selection of an LDS or multiple LDSs should align with the pipeline operator's strategic objectives.
— the special case of non-regulated pipelines;
— pipelines that do not or cannot have all of the required instrumentation;
— pipelines that do not meet the common criteria for effective LDS, such as those operating with two-phase or multiphase flow;
— pipelines with a history of very small (seepage) leaks;
— pipelines with a history of ruptures;
— pipelines with unique operating histories that characterize significant operational challenges.
Modifying Selection for Particular Requirements of Individual Pipelines
Operators must verify that the operational conditions and design of a pipeline can be supported by a baseline Leak Detection System (LDS) used on other lines Since LDSs are engineered systems, their performance can vary across different pipelines, potentially necessitating an additional LDS or modifications to the existing system Furthermore, the installation of extra instrumentation or operational changes may be required to ensure effective leak detection on various pipelines.
Periodic Review of Selection
The operator should regularly assess the selection of Leak Detection Systems (LDSs) to confirm their effectiveness in meeting leak strategy requirements This review may be prompted by changes in population or environmental conditions near the pipeline, advancements in technology or operating conditions, or conducted on a scheduled basis.
A potential strategy for a timed cycle involves reviewing leak detection requirements every five years, akin to a baseline Integrity Management Plan (IMP) This review would focus on the criteria specified in 49 CFR Part 195.452, employing a team of leak detection and risk experts who utilize a risk matrix or similar ranking method The team would specifically examine Safety Alerts (SAs), leak detection alarms, and other performance-related data to ensure the Leak Detection Program (LDP) remains up-to-date The selection process can then be reapplied to adapt to new conditions.
Improvements or other changes to LDSs or the LDP may be triggered by new circumstances such as:
— program modified by field experience;
— availability of new LDSs or extensions, to be evaluated by selection criteria;
— re-evaluation of the leak detection methods based on an established cycle;
— new pipelines are built and require leak detection;
— pipeline service is changed or there are significant instrumentation or measurement changes;
— a requirement for enhanced leak detection.
7 Performance Targets, Metrics, and KPIs
General
Hazardous liquid pipeline operators must set performance targets for their leak detection systems (LDSs) and monitor key performance indicators (KPIs) to ensure these targets are achieved These performance targets are usually integrated into the operator's leak detection strategy, guiding the selection and implementation of LDSs that align with these objectives.
In this RP, "metric" and "KPI" are interconnected, with metrics like reliability being quantified by KPIs such as the number of non-leak alarms KPIs should be specific and measurable, aimed at achieving overarching goals like high reliability for a pipeline operator's LDP API 1130, Annex C outlines metrics including sensitivity, reliability, accuracy, and robustness, applicable not only to CPM leak detection but also to various LDSs Additionally, API 1130, Annex DC offers a detailed description of these metrics and recommends performance KPIs, which are quantified by the pipeline operator, with potential assistance from the leak detection vendor.
Performance targets and key performance indicators (KPIs) are established at the LDP level for specific LDS instances, particularly regarding their implementation on designated pipelines The performance monitoring conducted by the pipeline operator for the overall LDP is detailed in Section 13 of this RP, which addresses program-level KPIs.
Determination of the leak detection KPIs and performance targets are predicated by the goals of the pipeline operator’s leak detection strategy.
The selection of Leak Detection Systems (LDSs) is influenced by Key Performance Indicators (KPIs) and performance targets, determining which LDSs are available in the Leak Detection Program (LDP) and their application to specific assets The LDP's continual improvement process and performance monitoring refine leak detection targets Metrics and KPIs for leak detection are established to ensure performance targets are achieved and to offer diagnostic insights when they are not met Statistical analysis of KPIs is essential for establishing suitable performance targets.
An option may be to use an independent third party to evaluate the LDS and management of KPIs.
Performance Metrics and Key Performance Indicators
To ensure leak detection objectives are achieved, it is essential to define, compute, and monitor performance metrics and KPIs These metrics should be continuously refined as part of an improvement process, enabling pipeline operators to assess their progress effectively When setting leak detection goals, the availability and clarity of KPIs must be considered, as overly broad or subjective goals can hinder measurement, while excessively specific goals may complicate future adjustments This balance is crucial to avoid dependency on a particular leak detection system vendor, which could pose challenges for upgrades or replacements For further insights, Annex D illustrates performance metrics and targets for a CPM LDS.
Key Performance Indicators (KPIs) can be tailored for both direct assessment and diagnostic purposes A KPI intended for direct assessment informs the pipeline operator about the achievement of performance targets For instance, if the performance target is set to a maximum threshold, it provides clear insights into operational efficiency.
Monitoring the number of alarms per month, excluding those triggered by an LDS test or actual leaks, serves as a key performance indicator (KPI) to assess target achievement Additionally, a KPI that measures column separation, or slack line, in the pipeline and tracks instances of exceeding a specified threshold can help diagnose the reasons behind the occurrence of excessive alarms.
LDS performance varies significantly based on pipeline operations, with internal LDSs like CPM showing different behaviors during shutdowns, steady conditions, transient operations, column separations, and varying flow rates Tracking each key performance indicator (KPI) for these distinct operating regimes can provide valuable data for making informed decisions regarding LDS performance.
To evaluate the Leak Detection Program (LDP) and establish a design foundation, it is essential to estimate the average time needed for the entire LDP, encompassing all implemented Leak Detection Systems (LDSs), to identify a leak across various potential leak rates.
7.2.3 Examples of Metrics, KPIs, and Performance Targets
This RP aims to address general LDP issues rather than focusing on a specific LDS The examples provided are designed to elucidate metrics, KPIs, and performance targets, serving as a framework for evaluating a pipeline operator's leak detection performance and strategy While these examples fall under the broader LDP metrics, they are not exhaustive or prescriptive, and their applicability may vary across different LDSs Given the rarity of actual leaks, it is often practical to monitor certain KPIs through validation testing.
The following KPIs may be used to assess leak detection reliability.
— Number of non-leak alarms (aka, false positive indications) per unit time (alarms/month), this may be tracked from observed data in normal operations.
The number of missed leaks, also known as false negative indications, or the percentage of missed leak events, is a key performance indicator (KPI) that can significantly fluctuate based on pipeline operations and the specific location of the leak along the pipeline.
— Number of hours that the LDS capability is degraded for example, due to component, electronics or software issues
The following KPIs may be used to assess leak detection sensitivity.
The average leak threshold is monitored for each observation time interval to evaluate sensitivity While it serves as a useful indicator, it's important to note that the probabilistic nature of many leak detection systems (LDSs) means that leaks exceeding the threshold might go undetected, whereas smaller leaks could be identified This data can be gathered from normal operational observations.
The minimum detectable leak size is monitored for each specific leak observation time interval to evaluate sensitivity It is theoretically feasible to estimate leak detection sensitivity metrics through an uncertainty analysis of the algorithms employed in the Leak Detection System (LDS).
— Overall leak volume on which the LDS alarmed
The following KPIs may be used to assess leak detection accuracy.
— Leak Flow Rate (Size) accuracy.
Many Continuous Pipeline Monitoring (CPM) systems continuously calculate flow imbalances, adjusting the line pack to compensate for these discrepancies This method effectively accounts for uncertainties, such as instrument errors and unknown pipeline operations, which are independent of leaks Consequently, it serves as a reliable proxy for accurately estimating leak flow rates during normal operations Techniques outlined in API 1149 can be utilized to estimate this type of operation.
— For both CPM and non-CPM systems leak flow rate accuracy may be observed during leak testing.
In CPM systems, the Key Performance Indicator (KPI) can significantly fluctuate based on pipeline operations and the specific location of leaks To fully assess the effectiveness of a CPM Leak Detection System (LDS), it is essential to observe or estimate leak size accuracy under various operational conditions.
— For external system this metric will likely be more consistent for different operations and leak locations.
— Leak location accuracy may be observed for both CPM and non-CPM LDS’s during leak testing.
— While API 1149 does not address leak location accuracy estimation, the techniques described in it may be used to do so for CPM LDS’s.
— This KPI may be expected to vary substantially with pipeline operation and somewhat with the location of the leak on the pipeline if a CPM is used.
— For external system this metric will likely be more consistent for different operations and leak locations.
Leak volume accuracy is closely related to leak size accuracy, as it is derived from the accumulated leak flow rate To accurately estimate leak volume, operators must understand the nature of the leak flow rate error If the error is purely due to precision, the leak volume error can be calculated using the root sum squared method Conversely, if the error is purely a bias, the leak volume error accumulates as the sum of the flow rate errors Assuming a purely bias error yields the most conservative estimate of leak volume accuracy.
Leak detection systems, like the Real Time Transient Model (RTTM), estimate variables such as flow rates and pressures based on measurements Significant discrepancies between measured and computed values can signal performance issues within the leak detection system (LDS) Although these deviations do not directly correspond to a specific metric, they serve as valuable diagnostic key performance indicators (KPIs).
Leak detection systems, like RTTM, automatically adjust parameters associated with pipe friction and heat transfer Deviations from acceptable ranges in these parameters signal potential performance issues within the leak detection system Although not directly linked to a specific metric, these adjustments serve as valuable diagnostic key performance indicators (KPIs).
Leak detection robustness refers to the performance of a leak detection system (LDS) when certain requirements, such as measurements, are unavailable The key performance indicators (KPIs) remain consistent with those previously mentioned, but they are assessed during periods when specific deficiencies are present in the LDS environment These deficiencies can encompass various factors that impact the system's effectiveness.
— loss of measurements, for instance, due to meter failure;
— unusual operating condition, such as draining the pipeline for maintenance, pigging, or operation during a column separation;
— LDS behavior during transient operating conditions.
Performance Targets
Performance targets establish the expectations for a pipeline operator regarding a Leak Detection System (LDS) based on risk tolerance These targets are crucial for selecting available LDSs in a Leak Detection Program (LDP) and for the initial identification of candidate LDSs for specific pipelines Additionally, performance targets are essential for the final selection of an LDS for an asset and for assessing opportunities for continuous improvement.
This RP aims to address general pipeline LDP management issues rather than focusing on a specific LDS To promote consistency among various LDSs, pipeline operators are encouraged to categorize their performance targets based on key metrics: sensitivity, reliability, robustness, and accuracy However, it is important to note that not all metrics may be equally suitable for every LDS.
A pipeline operator can prioritize various metrics based on the specific Leak Detection System (LDS) or asset in use For instance, metrics for an LDS designed for rupture detection differ significantly from those used for detecting small leaks.
Care should be taken in selecting performance targets Tailor performance targets to the level at which they are being directed The performance targets for an LDS may reflect:
— the targets of the pipeline operator’s LDP strategy may be broadly stated (e.g sensitivity of less than 20 %);
— the attributes of the LDS employed may be more focused but may be given as ranges (e.g sensitivity of less than 5 % to 10 %);
— the details of the pipeline implementation may be specific (e.g sensitivity of less than 5 %);
— reduction in risk as a target.
An LDS often has various performance targets, which stem from key metrics such as reliability, sensitivity, accuracy, and robustness These multiple targets can emerge when assessing different operating modes For instance, in the case of CPM, the sensitivity requirements may vary during shutdown, steady state, and transient operations.
When establishing targets with various performance metrics, conflicts can occur, particularly in leak detection methods where sensitivity and reliability often clash To address these conflicts, it is essential to prioritize certain metrics to find a balance between them.
Performance targets must be established through reliable engineering expertise and sound judgment Generic performance claims from vendors or proponents of a Local Distribution System (LDS) cannot replace systematic, engineering-based methods for setting these targets Instead, performance targets should be derived from careful estimation or direct observation of the LDS's performance.
Performance estimation and observation techniques provide insights into the expected capabilities of a pipeline's LDS, rather than yielding a definitive performance target For example, an API 1149 analysis can indicate the optimal performance of a CPM system under stable conditions, but real-world transient conditions may hinder achieving this performance While monitoring the system's performance offers a benchmark that can be reached, it does not inherently promote improvement Nonetheless, understanding these performance metrics can help operators set realistic and attainable goals for the LDS.
7.3.3.2 Determination of Performance Targets by Estimation
Performance estimation relies on a comprehensive understanding of the Leak Detection System (LDS) and the influence of its inputs and operational environment on performance API 1149 exemplifies this approach for Continuous Pipeline Monitoring (CPM) LDSs, discussing uncertainties that affect leak detection performance This principle is also applicable to externally based LDSs, with Annex C illustrating how four uncertainty factors impact leak detection capabilities across different calculation windows Pipeline operators can benefit from these calculations to enhance their understanding of LDS capabilities The core output of API 1149 highlights the LDS's sensitivity over time, applicable to both CPM and non-CPM systems Performance estimation is most effective when detailed knowledge of the asset, LDS, and operations is available, particularly for installed assets or those with comprehensive design specifications, enabling the application of techniques like uncertainty analysis.
The advantages of estimation are:
— may be performed before an LDS is implemented;
— allows comparison of different LDSs for an asset;
— provides prediction of the effects of changes to the configuration or operation of the asset or of the LDS.
The disadvantages of estimation are:
— it is a theoretical exercise that is not perfectly accurate, and the accuracy of the estimation is generally not known;
When evaluating various LDSs, if the disparity in estimation accuracy aligns closely with the differences in the estimated accuracy, it fails to offer a clear basis for selection and could potentially lead to misleading conclusions.
— the configuration of the asset should be known in great detail, including items such as accuracy and precision of inputs that are difficult to obtain or assess;
— the physical principle of the technique used for the LDS should be known in detail however, this may not be available for proprietary technologies;
— derivation of the uncertainty relations for an LDS require a thorough understanding of the mathematics and statistics of uncertainty analysis.
7.3.3.3 Determination of Performance Targets by Observation
Performance observation involves analyzing the historical performance of the LDS and conducting tests to assess its current performance This technique is suitable when there is a comprehensive understanding of the asset and its operations, yet the actual performance remains uncertain It is essential to evaluate the performance of the existing asset and its operations However, setting performance targets through observation can be difficult for externally based LDSs.
The advantages of observation are:
— it provides a definitive result for the performance;
— it accounts for as-built, real-world conditions.
The disadvantages of observation are:
— it does not identify factors limiting the performance;
— it does not provide predictive information on how changing the configuration or operation of the pipeline system may affect performance.
7.3.4 Additional Factors in Determination of Performance Targets
The methods of estimation and observation for determining performance targets are complementary For instance, observing the performance of a CPM LDS on a specific asset provides a definitive measure of its effectiveness Performance estimation techniques, such as API 1149, can predict expected performance changes due to operational or configuration adjustments An API 1149 analysis helps assess whether observed performance aligns with expectations or indicates potential issues with the LDS The key output of API 1149, which reflects an LDS's sensitivity over time, is applicable to both CPM and non-CPM LDSs Sound engineering practices and experience guide the decision-making process regarding discrepancies between estimated and observed performance, determining whether they stem from estimation inaccuracies or require further investigation.
Using a combination of estimation and observation methods allows for the tuning of inputs to estimation techniques based on observed performance However, caution is essential, as this process may yield inputs that align with the observations used for tuning but could lead to inaccurate results when estimating the performance of the system under new operations or configurations.
7.3.5 Developing Performance Targets for LDSs
Both estimation and observation are essential for assessing the performance of a specific Liquid Distribution System (LDS) applied to an asset By analyzing multiple pipelines with similar characteristics, operators can make generalizations about LDS performance For example, a pipeline operator might find that their uncompensated volume balance achieves X% sensitivity compared to Y% for their compensated volume balance While this is a simplification, such generalized metrics can be valuable for making initial decisions regarding the selection of an LDS for an asset.
LDSs implemented in an LDP must undergo testing upon implementation and regularly, not exceeding five years, or following significant operational or physical changes in the pipeline The testing process should adhere to the requirements specified in API 1130, which should be customized to reflect the unique characteristics of the LDS and the specific assets involved Additionally, actual leaks may serve as a substitute for periodic testing as per API 1130 guidelines.
Operators must identify the right moments to employ evaluation and validation testing Whenever feasible, testing should align with the recommendations provided by the LDS manufacturer or developers.