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ASME B31.8S-2016 pdf download

ASME B31.8S-2016 pdf download.Managing System Integrity of Gas Pipelines.
Ifthe operational mode changes and pipeline segments are subjected to significant pressure cycles, pressure differential, and rates of change of pressure fluctuations, fatigue shall be considered by the operator, including any combined effect from other failure mechanisms that are consideredto bepresent, suchas corrosion. Ausefulrefer- encetohelptheoperatorwiththisconsiderationisGRI04- 0178, Effect of Pressure Cycles on Gas Pipelines. 2.3 The Integrity Management Process The integrity management process depicted in Figure 2.1-2 is described below. 2.3.1 Identify Potential Pipeline Impact by Threat. Thisprogramelementinvolvestheidentificationofpoten- tial threats to the pipeline, especially in areas ofconcern. Each identified pipeline segment shall have the threats considered individually or by the nine categories. See para. 2.2. 2.3.2 Gathering, Reviewing, and Integrating Data. The firststep inevaluatingthe potential threats forapipe- line system or segment is to define and gather the neces- sary data and information that characterize the segments and the potential threats to that segment. In this step, the operator performs the initial collection, review, and inte- grationofrelevantdataandinformationthatareneededto understandtheconditionofthepipe; identifythelocation- specific threats to its integrity; and understand the public, environmental, and operational consequences of an inci- dent. The types of data to support a risk assessment will varydepending on the threatbeing assessed. Information on the operation, maintenance, patrolling, design, oper- ating history, and specific failures and concerns that are unique to each system and segment will be needed. Relevant data and information also include those conditions or actions that affect defect growth (e.g., deficiencies in cathodic protection), reduce pipe properties (e.g., field welding), or relate to the introduc- tion ofnewdefects (e.g., excavation worknear a pipeline). Section 3 provides information on consequences. Section 4 provides details for data gathering, review, and integra- tion of pipeline data. 2.3.3 RiskAssessment. Inthisstep,thedataassembled from the previous step are used to conduct a risk assess- ment of the pipeline system or segments. Through the integrated evaluation of the information and data collected in the previous step, the risk assessment process identifies the location-specific events and/or conditions that could lead to a pipeline failure, and provides an understanding of the likelihood and conse- quences (see section 3) of an event. The output of a risk assessment should include the nature and location of the most significant risks to the pipeline. Under the prescriptive approach, available data are compared to prescribed criteria (see Nonmandatory Appendix A). Risk assessments are required in order to rank the segments for integrity assessments. The performance-based approach relies on detailed risk assessments. There are a variety of risk assessment methods that can be applied based on the available data and the nature of the threats. The operator should tailor the method to meet the needs of the system. An initial screening risk assessment can be bene- ficial interms offocusingresources onthe mostimportant areas to beaddressedandwhereadditionaldatamaybeof value. Section 5 provides details on the criteria selection for the prescriptive approach and risk assessment for the performance-based approach. The results of this step enable the operator to prioritize the pipeline segments forappropriate actions thatwill be defined inthe integrity management plan. Nonmandatory Appendix A provides the steps to be followed for a prescriptive program. 2.3.4 Integrity Assessment. Based on the risk assess- mentmade in the previous step, the appropriate integrity assessments are selected and conducted. The integrity assessment methods are in-line inspection, pressure testing, direct assessment, or other integrity assessment methods, as defined in para. 6.5. Integrity assessment method selection is based on the threats that have been identified. More than one integrity assessment method may be required to address all the threats to a pipeline segment. A performance-based program may be able, through appropriate evaluation and analysis, to determine alter- native courses of action and time frames for performing integrityassessments. Itis the operator’s responsibilityto document the analyses justifying the alternative courses ofaction ortime frames. Section 6 provides details on tool selection and inspection. Data and information from integrity assessments for a specific threat may be of value when considering the presence ofother threats and performingriskassessment for those threats. For example, a dent may be identified when running a magnetic flux leakage (MFL) tool while checking for corrosion. This data element should be inte- grated with other data elements for other threats, such as third-party or construction damage. Indications thatare discovered duringinspections shall be examined and evaluated to determine iftheyare actual defects or not. Indications may be evaluated using an appropriate examination and evaluation tool. For local internal or external metal loss, ASME B31G or similar analytical methods may be used.

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