Previous Issue: New Next Planned Update: 19 July 2014Page 1 of 14 Primary contact: on 966-3-8730674Engineering ProcedureSAEP-27 19 July 2009Pipelines/Piping Hydraulic Surge AnalysisDocument Responsibility: Process and Control Systems Dept.Saudi Aramco DeskTop StandardsTable of Contents1 Scope (2)2 Conflicts and Deviations (2)3 Applicable Documents (2)4 Definitions (4)5 Instructions (5)6 Responsibilities (11)Exhibits (12)Next Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis1 ScopeThis Saudi Aramco Engineering Procedure (SAEP) provides technical guidance todefine full scope of hydraulic surge analysis during DBSP, Project Proposal, DetailedDesign and throughout the different stages of a project cycle and throughout theoperational life of a pipeline to ensure consistent approach. It provides Saudi Aramcoengineers and engineering design contractors with guidelines describing therequirements to conduct and review pipelines hydraulic surge analysis studies forexisting and new facilities.2 Conflicts and Deviations2.1 Any conflicts between this standard and other applicable Saudi AramcoEngineering Standards (SAESs) or industry standards, codes, and forms shall beresolved in writing through the Manager, Process & Control Systems Departmentof Saudi Aramco, Dhahran.2.2 Direct all requests to deviate from this standard in writing to the Company, whoshall follow internal company procedure SAEP-302 and forward such requests tothe Manager, Process & Control Systems Department of Saudi Aramco, Dhahran.3 Applicable DocumentsTo ensure compliance with the appropriate Saudi Aramco and International Standardsand Codes for over pressure protection of pipelines, the following EngineeringStandards shall be reviewed in conjunction with hydraulic surge analysis studies. These Standards encompass hydraulic analysis, surge analysis, over pressure protection ofpipelines, design pressure, materials, operating conditions, Maximum AllowableOperating Pressures and Maximum Allowable Surge Pressures.3.1 Saudi Aramco ReferencesSaudi Aramco Engineering ProceduresSAEP-12 Project Execution PlanSAEP-14 Project ProposalSAEP-302 Instructions for Obtaining a Waiver of aMandatory Saudi Aramco EngineeringRequirementSAEP-303 Engineering Reviews of Project Proposal andDetail Design DocumentationNext Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis SAEP-354 High Integrity Protective Systems DesignRequirementsSAEP-363 Pipeline Simulation Model Development andSupportSaudi Aramco Engineering StandardsSAES-B-017 Fire Water System DesignSAES-B-058 Emergency Shutdown, Isolation, and DepressuringSAES-B-060 Fire Protection for Piers, Wharves and SeaIslandsSAES-B-064 Onshore and Nearshore Pipeline SafetySAES-B-070 Fire and Safety Requirements for Bulk PlantsSAES-J-600 Pressure Relief DevicesSAES-J-601 Emergency Shutdown and Isolation SystemsSAES-J-605 Surge Relief Protection SystemsSAES-J-700 Control ValvesSAES-L-100 Applicable Codes and Standards for PressurePiping SystemsSAES-L-132 Material Selection of Piping SystemsSAES-L-310 Design of Plant PipingSAES-L-410 Design of PipelinesSaudi Aramco Engineering ReportsSAER-5437 Guidelines for Conducting HAZOP StudiesSAER-6043 High Integrity Protection System (HIPS)Evaluation Team Report3.2 International Standards and CodesANSI/ASME Code “Process Piping” Chemical plant and petroleum refinerypipeline for in-plant pipingANSI/ASME B16.5 Pipe Flanges and Flanged FittingsANSI/ASME B31.1 Power PipingANSI/ASME B31.3 Chemical Plant and Petroleum Refinery Pipelineor In-Plant PipingNext Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis ANSI/ASME B31.4 Liquid Petroleum Transportation Piping Systemsfor Cross-Country Liquid PipelinesANSI/ASME B31.8 Gas Transmission and Distribution PipingSystemsAmerican Petroleum InstituteAPI STD 521 Pressure-Relieving and Depressuring Systems American Water Works AssociationAWWA M45 American Water Works Association, FiberglassPipe DesignNational Fire Protection AssociationNFPA 24 Installation of Private Fire Services Mains andtheir AppurtenancesNFPA 25 Inspection, Testing and Maintenance of Waterbased Fire Protection Systems4 DefinitionsHydraulic Surge:Also referred to as “water hammer.” This is a phenomenon inpipeline operations characterized by a sudden increase in internal pressure. Hydraulicsurge is often caused by the transformation of kinetic energy to potential energy as astream of fluid is suddenly stopped.Surge Analysis: An engineering study that is undertaken to perform a hydraulic transient analysis of a specific system through the use of specialized simulation software whichmodels the system, fluid and operating conditions. The transient analysis will predict the time history of pressures and flows throughout a system as a result of potentiallyapplicable transient events. From the results, an experienced engineer/specialist candetermine whether additional surge protection is required, what form of surge protection is most suitable, its capacity and where it should be located. The surge/transient analysis referred to in this Standard is specific to pipelines/piping systems.HAZOP (Hazard and Operability): A systematic, detailed analysis technique applied to identify hazards and operability issues which have the potential to place the process plant, environment or personnel at risk. The HAZOP study identifies abnormal process deviations that may require additional protective functions. The HAZOP analysis shall follow the guidelines of SAER-5437, Saudi Aramco HAZOP Engineering Report.PHA (Preliminary Hazards Analysis): An initial screening exercise that can be used to identify, describe, and rank major hazards. This technique can also be used toNext Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis identify possible consequences and likelihood of occurrence and providerecommendations for hazard mitigation.5 Instructions5.1 General Requirements5.1.1 PMT shall provide a copy of this Engineering Procedure to theEngineering design contractor involved in conducting the hydraulic andsurge analysis study and a full comply to this procedure shall be notifiedto the contractor.5.1.2 Risk assessment studies such as PHA or HAZOP, if available, shall beused as a basis for the surge analysis. The whole risk assessment (PHAand HAZOP) shall be an exercise in which all concerned parties(stakeholder organizations) are involved in sharing awareness andresponsibility for the decisions and assumptions made to commence thesurge analysis study. The risk assessment shall be conducted as definedin SAEP-12, SAEP-14 and SAEP-303.5.1.3 The engineering design contractor shall use the approved pipelinesimulation software that is defined in the Saudi Aramco RecommendedSimulation Software Vendor List. The approved list can be obtainedfrom P&CSD/Pipelines & Simulation Unit.5.1.4 At the completion of the hydraulic surge studies, the engineering designcontractor shall submit an electronic copy of complete simulation modelsand supporting documents to P&CSD/Pipelines & Simulation Unit, theProponent and FPD for review and approval.5.2 Surge Analysis Preparation ProceduresThe hydraulic surge analysis study shall be undertaken if over pressure ortransient risks to piping or pipelines are identified in the following phases of aproject or where changes to operating conditions are made including:1) Conceptual and Feasibility studies have been completed, detailed engineeringdesign such as DBSP, Project Proposal and Detailed Design is in progress.2) Prior to any change in existing pipeline operation or modification to thepipeline system. If the maximum flow rates or maximum operatingpressures increased from the previous operation, a new surge analysis at thenew conditions to ensure that the pipeline system is protected.3) Any change or equipment data update in the detailed design, final pipelinedesign, at the last minute, or during construction works.Next Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis4) During commissioning and start up activities, especially for testing sectionsof the pipeline system or if the tested system is different from the standarddesign configuration.The study shall not be limited to the mentioned transient risk situations andP&CSD shall endorse the hydraulic surge analysis study timing.Before the surge analysis commences, a technical specification for the surgeanalysis study shall be prepared and approved by Proponent or SAPMT’sengineering contractor to acknowledge the problem for further assessment,scope development, and possible surge protection solution. The following listshall be completed to define full scope of the surge analysis for pipelines toensure a consistent approach for all projects.5.2.1 Analysis ObjectiveThe objective of the analysis will determine the extent of the pipelinesystem to be modeled and the accuracy of data required during pipelinemodel development and evaluation. A clear surge analysis objectiveshall be prepared and agreed with the pipeline hydraulic and surgeanalysis specialist of P&CSD prior to conducting the analysis.5.2.2 Pipeline System ScopeHydraulic surge analysis shall not be limited by project scope of work.The whole pipeline system needs to be analyzed and the model built forhydraulic surge analysis shall include all the possible causes from withinor beyond project scope boundaries and interfaces with other relatedfacilities.5.2.3 Possible Scenarios of Surge AnalysisThe transient/surge flow conditions that are expected to occur shall bedefined. The analysis shall look at various possible causes, identify thecritical cases, specify and design the necessary surge protection systemas identified during the PHA, HAZOP and surge analysis studies.Exhibit II shall be used as a checklist to identify potential causes oftransient pressure. As a minimum the following potential causes ofliquid piping overpressure shall be investigated:a) Inadvertent closure of a pipeline Class-1 or Class-2 valve.b) Closure of a downstream plant ESD valve.c) Trip of intermediate pump.Next Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysisd) Closure of one looped pipeline.e) Closure of more than one looped pipeline.f) Closure of isolation valves, inside interfacing, upstream anddownstream.g) Closure or control failure of a pipeline or downstream control valve.h) Inadvertent start of a standby pump, in addition to existing pump(s)operationi) Impact of new pipeline interfacing with existing pipeline5.2.4 Data RequirementsThe following list identifies data that shall be gathered before a surgeanalysis study is conducted:a) Pipeline system data: General description of the pipeline system,function and a summary of the likely hazard scenarios as identifiedin the PHA and HAZOP studies. Pipeline data including length,elevation profile, diameter, wall thickness, roughness or frictionfactor, elastic (Young’s) modulus, pressure rating, maximumpermissible pressure (pipes, components, joints, support), minimumacceptable pressure (pipes, components, joints, supports).b) Operating conditions: pipeline inlet pressure and temperature,arrival pressure, maximum and minimum flow rates.c) Fluid data: The key data required are the physical properties at therelevant operating pressure and temperature for the evaluatedpipeline system. Physical properties include: density, viscosity, truevapor pressure, bulk modulus, working temperature. Alternatively,for compositional analysis, the fluid composition shall be defined.d) Ambient conditions (summer/winter temperatures), thermalconductivities for pipelines and soil and/or the overall heat transfercoefficient between the pipeline and soil.e) Pumps: Type, number, location, performance characteristics, withoperating curves and the following rated conditions: (head, flow,speed, power and efficiency), Inertia of rotating elements (impeller,motor and coupling)f) Valves: Type, number, location, dynamic performance characteristic(Cv curve), open/close time, pressure rating and maximumpermissible pressure. Additional data for pressure relief valves: setNext Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysispressures for opening and closing, time needed to open and close,discharge pressure.g) Tanks: Location, general layout, dimensions, maximum, minimumand normal levels of the liquid surface, elevation relative to themain pipeline, length and diameter of the connecting piping.h) Bypass piping: Location, length, diameter, head loss.i) Surge and transient event data: Time scale of valve and pumpsoperation (Control Logic) and sequence of events to be investigated.j) Units of measurements must be consistent.5.2.5 Surge Analysis Methodology1) The analysis shall be performed first without assuming theintervention of any overpressure protection devices or equipments.Refer to Exhibit II for a list of potential causes of a transientpressure in a pipeline/piping system.2) Additional analysis shall be performed where the introduction ofmodifications to the system design are made to mitigate identifiedoverpressure conditions, e.g., trimming pump impellers, increasingpipe wall thickness, removing or modifying the device causing theexcessive transient pressures, adding overpressure protectionequipment such as relief systems as specified in SAES-J-600 andSAES-J-605 or HIPS as per Saudi Aramco Engineering Procedure& Report SAEP-354 & SAER-6043.Surge analysis shall ensure compliance with the appropriate SaudiAramco and International Standards and Codes ANSI/ASME B31.1,ANSI/ASME B31.3, ANSI/ASME B31.4, ANSI/ASME B31.8, orANSI/ASME B16.5 for over pressure protection of pipelines and processpiping. For fire water and safety related systems, surge analysis shallensure compliance with the appropriate International Standards CodesAPI STD 521, AWWA M45, NFPA 24 and NFPA 25.Surge analysis studies shall be conducted assuming that process initiatedshutdown signals triggering pump trips, due to low suction and highdischarge pressure, successfully stop pumps. This is provided that suchsignals originate from an ESD system and the signal loops and ESDsystem meet the required Safety Integrity Level (SIL) assessment anddesign requirements of SAES-J-601.Next Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis5.2.6 Pipeline Model ValidationWhen plant and pipeline operating data is available, the model shall bevalidated against a set of operating data within the known constraints of,1) accuracy of plant measurements, 2) tolerance and convergencelimitations within the simulator, and 3) the errors associated withsimplifying assumptions made during model development. Models shallbe validated also during project proposal and/or detailed design bySAPMT’s engineering contractor.Before the data can be applied to the model, it shall be necessary toevaluate the quality of the measurements caused by faulty instruments.If available, a software package shall be used to evaluate all elements ofthe data. The software package shall reconcile the data to identify faultyinstruments and to eliminate or reduce measurements errors.Following model validation, if it is determined that the model results arenot within acceptable limits, tuning of specific parameters may berequired to improve accuracy. Model parameters may only be changed,following discussion and agreement with P&CSD. Typically, thedifference between pipeline model results and operating data can be lessthan 2%. If the discrepancies are greater than 2%, the design contractorshall submit explanations for the discrepancies to P&CSD and seekapproval to use the model for studies. This is covered by SAEP-363.5.3 Documentation RequirementsA surge analysis specific sheet shall be developed per Exhibit I and submittedfor approval prior to performing surge analysis.At the completion of the transient analysis studies, documentation shall bedeveloped containing, as a minimum requirement, the following sections:a) An executive summary that shall include a brief description of the problemunder investigation, background, objective, proposed solution, tool usedand concluding remarks.b) A system description of the pipeline and study objectives.c) A description of the model including a detailed description of thesimulation software components being used.d) A description of each scenario adopted for the study.e) Operation Control Philosophy/Logic implemented in the simulation.f) The methodology used to extract, reconcile, and filter the operating data.g) Model drawings.Next Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysish) Tabulated results for each scenario.i) Graphical results representing time plots and/or profile plots of criticalvariables to support conclusions established for each scenario.The following sections provide a detailed description of requirements for thedocumentation.5.3.1 Study ObjectiveDescribe the purpose of the study and the role that simulation plays inaddressing that purpose. The objective of the simulation must be clearlystated. The model shall be represented as a tool to help solve specificproblems or answer specific questions rather than as an end product. Thesimulation package and version used to build the model shall be defined.5.3.2 Work ScopeDescribe the system under investigation. The level of detail, modelboundaries, sources of feed…etc. This can be accomplished byreferencing available documents. Major relevant system characteristicsshould be summarized in the report that describes the simulation.5.3.3 Study AssumptionsIn order to understand the model and its limitations, all assumptions shallbe identified. Discuss the limitations of the model’s representation of theactual system and the impact those limitations have on the results andconclusions presented.5.3.4 Property PackageDescribe the thermodynamics packages that were utilized to define thefluid properties. Flow, heat transfer and pressure drop correlations mustalso be described.5.3.5 System Drawings (PFD’s, P&ID’s and Model Sketches)Provide the modeled system Process Flow Diagrams and ProcessInstrumentation Diagrams. Also, provide the simulation schematic usedto build the model and compare the simulation model with the overviewand actual pipelines/process to highlight differences.5.3.6 Model Results AnalysisPresent the calibration criteria, procedure, and results. Describe thesource of the observed data to which model results are compared.Next Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis Explain the appropriateness of using these data for model comparisonsand the basis for any adjustments made to actual observations whenmaking the comparisons. It is important to report and use as many typesof data as possible for successful calibration of the model.5.3.7 Results Analysis Profile and TrendsProvide results analysis in profiles (specific variables vs. length ofpipeline) and trends (specific variables vs. time) for all the evaluatedcases.All the prepared document shall be submitted to P&CSD for review andapproval.6 ResponsibilitiesP&CSD provides technical guidance for all hydraulic and surge analysis, or pipelinecontrol system studies during DBSP, Project Proposal, and Detailed Design phases of a project. P&CSD proactively works with Proponent and SAPMT on pipeline design;reviews all related pipelines studies and models; and provide guidance during eachdesign stage. It is P&CSD responsibility to approve and endorse the pipeline studiesand models.SAPMT or proponent shall be responsible for obtaining approval for the surge analysis technical specification (Exhibit I) from the appropriate organizations prior toperforming the analysis. If any changes are made to the system or its operatingconditions or procedures, the technical specification shall be revised.It is the responsibility of Proponent and SAPMT to consider the implications of pipeline transient risk assessment, if the project scope is changed or it is part of a phaseddevelopment.Suppliers for pipeline and related components such as surge relief, rotating equipments shall provide Saudi Aramco and the design contractor the required equation data forconducting detailed surge analysis studies.Revision Summary19 July 2014 New Saudi Aramco Engineering Procedure.Next Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge AnalysisEXHIBITSTABLE OF CONTENTSEXHIBIT I Surge Analysis Technical Specification – Summary SheetEXHIBIT II List of Potential Causes of Transient Pressure in a Pipeline/PipingSystem – ChecklistNext Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge AnalysisEXHIBIT I – Surge Analysis Technical Specification – Summary SheetThe following sheet summarizes minimum surge analysis requirements for the pipeline system specified. The analysis report that follows from this is only valid for the pipeline system as defined. If any changes are made to the system or its operating conditions or procedures, the report shall be reviewed.____________________________________________________________________________ Project Name:Scope:Data Requirements: Data requirements as listed in Section 4.2 of the Procedure Design and Operating Criteria: Pipelines & Piping Design as per Saudi Aramco EngineeringStandards (SAES-L-100, SAES-L-132, SAES-L-310 andSAES-L-410)Fire and Safety related system design as per Saudi AramcoEngineering Standards (SAES-B-017, SAES-B-060,SAES-B-064 and SAES-B-070)Design Constrains:Maximum operating PressureMinimum operating PressureMaximum Flow RateMinimum Flow RateOther ParametersPipeline Transient Criteria:Maximum Transient PressureMinimum permitted pressureOther ParametersTransient Pressure Causes and scenarios List of the causes to be investigatedStudy Basic AssumptionsRecommended Surge Protection Systems This should be modified as required.Operational Requirements Constrains that should be included in the operationinstruction manualDate:Specification completed by: ______________________*Approved by:Proponent Representative ______________________P&CSD Representative ______________________* P&CSD shall decide on the approval levelNext Planned Update: 19 July 2014 Pipelines/Piping Hydraulic Surge Analysis EXHIBIT II – List of Potential Causes of Transient Pressure in a Pipeline/Piping System– Checklist____________________________________________________________________________ Item No. Possible Causes____________________________________________________________________________1. Inadvertent closure of a pipeline Class-1 or Class-2 valve as per SAES-B-058.2. Closure of a downstream plant ESD valve.3. Trip of intermediate pump.4. Closure of one looped pipeline.5. Closure of more than one looped pipeline.6. Closure of isolation valves, inside interfacing, upstream and downstream.7. Closure or control failure of a pipeline or downstream control valve as per SAES-J-700.8. Impact of new pipeline interfacing with existing pipeline.9. Inadvertent start of a standby pump, in addition to existing pump(s) operation10. The pipeline system start up and shutdown11. The lineup of the pipeline is changed12. The flow rate or capacity of the pipeline system increases/decreases13. Changes are made to the original design of the system14. Component (e.g., flow/pressure control valve, surge relief valve, etc.) malfunctions15. Basic design data (flow rates, fluid properties, materials spec., etc,) are inaccurate16. The surge protection system and control fail17. Any other potential causes that a risk assessment (PHA & HAZOP) identifies。