1、 Design Guidelines for Installation of Automatic Shut-off Valve (ASV) and Remote Control Valve (RCV) Systems In Natural Gas Transmission Pipelines i Design Guidelines for Installation of Automatic Shut-off Valve (ASV) and Remote Control Valve (RCV) Systems In Natural Gas Transmission Pipelines Octob
2、er 2012 AGA Distribution and Transmission Engineering Committee Copyright 2012 American Gas Association, All Rights Reserved ii iii DISCLAIMER AND COPYRIGHT The American Gas Associations (AGA) Operations and Engineering Section provides a forum for industry experts to bring collective knowledge toge
3、ther to improve the state of the art in the areas of operating, engineering and technological aspects of producing, gathering, transporting, storing, distributing, measuring and utilizing natural gas. Through its publications, of which this is one, AGA provides for the exchange of information within
4、 the gas industry and scientific, trade and governmental organizations. Each publication is prepared or sponsored by an AGA Operations and Engineering Section technical committee. While AGA may administer the process, neither AGA nor the technical committee independently tests, evaluates or verifies
5、 the accuracy of any information or the soundness of any judgments contained therein. The purpose of this paper is to provide guidance to natural gas service companies with transmission pipelines in evaluating, implementing and installing ASVs and RCVs. AGA disclaims liability for any personal injur
6、y, property or other damages of any nature whatsoever, whether special, indirect, consequential or compensatory, directly or indirectly resulting from the publication, and use of or reliance on AGA publications. AGA makes no guaranty or warranty as to the accuracy and completeness of any information
7、 published therein. The information contained therein is provided on an “as is” basis and AGA makes no representations or warranties including any expressed or implied warranty of merchantability or fitness for a particular purpose. In issuing and making this document available, AGA is not undertaki
8、ng to render professional or other services for or on behalf of any person or entity. Nor is AGA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a compet
9、ent professional in determining the exercise of reasonable care in any given circumstances. AGA has no power, nor does it undertake, to police or enforce compliance with the contents of this document. Nor does AGA list, certify, test or inspect products, designs or installations for compliance with
10、this document. Any certification or other statement of compliance is solely the responsibility of the certifier or maker of the statement. AGA does not take any position with respect to the validity of any patent rights asserted in connection with any items that are mentioned in or are the subject o
11、f AGA publications, and AGA disclaims liability for the infringement of any patent resulting from the use of or reliance on its publications. Users of these publications are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, i
12、s entirely their own responsibility. Users of this publication should consult applicable federal, state and local laws and regulations. AGA does not, through its publications intend to urge action that is not in compliance with applicable laws, and its publications may not be construed as doing so.
13、Changes to these guidelines may become necessary from time to time. Suggested changes to this document should be communicated to AGA by completing the last page of this report titled, “Form for Proposal to Change Design Guidelines for Installation of ASV or (2) for steel pipe manufactured in accorda
14、nce with an unknown or unlisted specification, the yield strength determined in accordance with 192.107(b). Supervisory Control and Data Acquisition (SCADA) System - A computer-based system or systems used by a controller in a control room that collects and displays information about a pipeline faci
15、lity and may have the ability to send commands back to the pipeline facility. 2.2. Regulations 2.2.1. Title 49 Code of Federal Regulations (49 CFR), Part 192, Subpart O Title 49 CFR 192.935 requires a pipeline operator to evaluate additional measures beyond those already required by Part 192 to prev
16、ent or mitigate specific threats to the pipeline in a High Consequence Area (HCA). One potential measure is the use of ASVs/RCVs, which is addressed in 49 CFR 192.935(c). Specifically: “192.935(c) Automatic shut-off valves (ASV) or Remote control valves (RCV). If an operator determines, based on a r
17、isk analysis, that an ASV or RCV would be an efficient means of adding protection to a high consequence area in the event of a gas release, an operator must install the ASV or RCV. In making that determination, an operator must, at least, consider the following factors5 swiftness of leak detection a
18、nd pipe shutdown capabilities, the type of gas being transported, operating pressure, the rate of potential release, pipeline profile, the potential for ignition, and location of nearest response personnel.” 2.2.2. Potential Future Regulations Mandated by the 2011 Pipeline Safety Reauthorization Leg
19、islation In December 2011, Congress passed the Pipeline Safety, Regulatory Certainty, and Job Creation Act of 2011. The president signed the pipeline safety bill into law on January 3, 2012. Section 4 of this law deals with ASVs and RCVs for new and entirely replaced transmission lines. It mandates
20、that the U.S. Department of Transportation (DOT), not later than two years after enactment and if appropriate, to require by regulation the use of automatic or remote-controlled shut-off valves, or equivalent technology, where economically, technically, and operationally feasible on transmission pip
21、eline facilities constructed or entirely replaced after DOT issues the final rule. It also requires the Comptroller General of the United States to conduct a study on the ability of transmission pipeline operators to respond to a hazardous liquid or gas release from a pipeline section located in a H
22、CA and report to Congress not later than one year after enactment. The study must consider the swiftness of leak detection and pipeline shutdown capabilities, location of the nearest response personnel and the costs, risks and benefits of installing automatic and remote-controlled shut-off valves. 2
23、.3. Benefits of Using ASVs/RCVs The potential benefits of installing ASVs/RCVs include the following: Timely interruption of the fuel source to a gas pipeline event allowing improved emergency response to the affected area. Providing a means to more rapidly close valves compared to manually operated
24、 valves located in difficult to respond to areas. 6 Closing valves more rapidly provides the opportunity for maintaining gas service to customers located outside of the affected pipe section by maintaining gas pressure to these customers. Reducing the economic and environmental issues associated wit
25、h a large unplanned gas release. Providing additional system control functionality for dealing with planned pipeline maintenance and shutdowns, and abnormal operating situations other than unplanned gas releases. 2.4. Potential Concerns with the Usage of ASVs/RCVs When utilizing ASVs/RCVs, there are
26、 a number of potential concerns that need to be taken into consideration. These include the following: Unintended or inappropriate automated valve closure. For ASVs, this could possibly result from increased flow rates or reduced pipeline pressures during winter peak load conditions and other less f
27、requently occurring operational variations at normal times. For RCVs, this could potentially be caused by a human decision-making error in deciding when to close an RCV. Industry experience has shown that ASVs are much more susceptible to unintended or inappropriate valve closures than RCVs. A valve
28、 closure, whether intended or unintended, may lead to widespread customer outages where re-establishing service could take days or weeks with the potential for human hardship and property damage in certain climate conditions. Susceptibility to physical and cyber security threats and vandalism. Possi
29、bility of equipment failure causing the valve control system and the automated valve to fail to function as designed. 7 Realization that not all unplanned gas releases would necessarily trigger an ASV to operate, or for an RCV, be identified by the SCADA system for a gas controller to take action. A
30、s discussed further in this paper, the proper selection, engineering design, installation and operation of ASVs/RCVs in a pipeline system can assist a pipeline operator in addressing these concerns. 8 3. System Design and Installation Considerations 3.1. System Design Philosophy and Objectives Every
31、 pipeline operator, whether installing a single ASV/RCV, or developing a comprehensive system of ASVs/RCVs for complex pipeline system isolation, should begin with a clear and consistently applied set of guidelines and criteria for the utilization and installation of automated valves. In developing
32、these guidelines and criteria, the following factors may be considered: Specific physical criteria related to the pipeline : o pipeline diameter, operating pressure and associated PIR or other metric; o pipeline SMYS, pipe condition and or material/fabrication properties. Threats from natural forces
33、, such as seismic zones, rivers, washout, landslide, subsidence zones and other special geographical features. Human impact consequence factors, such as location class and adjacencies with special high-density facilities (e.g. stadiums/arenas), including those that would be difficult to evacuate. Ma
34、ximum acceptable time to identify and isolate an affected pipeline section and subsequently to depressurize the pipeline. Valve location and accessibility, including location of nearest operator personnel with consideration given to man-made, seasonal or geographic inhibitors to rapid response. Mini
35、mum magnitude of a pipeline event that realistically can be detected and managed through ASV operation. (Normal operations also can cause pressure changes on a pipeline that mimic a pipeline event). Customer service impact: o risk-tolerance for customer loss in the event of accidental closure, 9 o m
36、agnitude of customer loss that can be managed if a pipeline event occurs, giving consideration to the logistics of restoration of service to a large number of customers, and o consideration of communicating with downstream major and critical customers about pipeline shutdown plans, both in advance a
37、nd during a pipeline event. Capital and operating costs. Considering each of these elements will help an operator define where and what type of sectionalizing block valves to install and operate, and the scope of such installations on their pipeline system(s). As pipeline operational requirements an
38、d dynamics change over time, such as from capacity expansions, customer load changes or regulatory requirements, operators must update their system isolation strategy and tactical plans accordingly. 3.2. Pipeline Sectionalization Design Considerations While each operator should develop its own pipel
39、ine isolation design philosophy, it is assumed for the discussion presented below that the objective in deploying ASVs or RCVs is to provide for rapid pipeline isolation in case of an unplanned gas release, while making every attempt to sustain service to critical customers and/or large population c
40、enters served by interconnected pipelines. The design of an ASV/RCV system for which loss of service to one or more customer(s) is a minor consideration may look very different than one in which sustaining customer service is imperative. While an operators final deployment philosophy may be differen
41、t than that assumed above, the fundamental considerations are common. While there are a number of factors that should be considered, the primary consideration is protection of the public. 3.2.1. Limitations imposed by pipeline network configuration The ability of any system of ASVs/RCVs to isolate a
42、 section of pipeline involved in a pipeline event while minimizing customer impacts depends, in part, upon the basic piping configuration of the system under consideration, and how amenable 10 that pipeline system is to taking discrete sections (mainline valve to mainline valve) out of service, whil
43、e still maintaining service to critical customers. These customers may reside downstream of an isolated pipeline section or be partially fed from the isolated pipeline section itself, and they may include interconnected pipelines, electricity generation plants, petroleum refineries, major manufactur
44、ing facilities and local natural gas distribution companies. For many operators, the base design of their pipeline system is such that it may take days or even months to determine and plan for the shutdown of key sections of pipeline for maintenance or repair operations while sustaining service to c
45、ustomers. Pre-work for such sections might include installation of bypass piping, installation of new valves, arranging temporary supplies using compressed natural gas (CNG) bottles or vessels, and/or rerouting system supplies via secondary pipelines. These same considerations must be given to any s
46、ystem design to isolate such pipeline sections with ASVs and RCVs in a much shorter planning interval. Without such consideration, installation of ASVs or RCVs may provide for reduced closure and event isolation time, but also may lead to loss of customers when the valves are closed. 3.2.2. Common T
47、ypes of Piping Configurations: Figure 3-1 shows the simplest form of pipeline configuration that can be equipped with automated valves to isolate an unplanned gas release. This configuration is representative of a simple long-distance gas transmission pipeline without taps in a section of pipe. When
48、 MLV2 and MLV3 are closed to isolate the affected pipeline section, service to customers downstream of the isolated section will be at-risk when the stored volume of gas (line-pack downstream of MLV3) is expended, unless these customers have access to some alternate source of fuel supply. 11 Figure
49、3-1 Simple Long Distance Gas Transmission Pipeline w/o Complex Piping Valve spacing, relative tap locations and piping interconnection schemes all play a critical role in achieving isolation success coupled with sustained customer service. Additional consideration should be given to any local production feeds into the transmission line. Some pipeline systems are designed to serve customers via taps from multiple locations, including tap valves “bridled” around both sides of a mainline valve, taps which may take off several miles apart from (
