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1、Firstly Quantify the Problem,“In physical science the first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it.I often say that when you can measure what you are speaking about,and
2、express it in numbers,you know something about it;but when you cannot measure it,when you cannot express it in numbers,your knowledge is of a meagre and unsatisfactory kind;it may be the beginning of knowledge,but you have scarcely in your thoughts advanced to the state of Science,whatever the matte
3、r may be.Lord Kelvin PLA,1883-05-03,Australian&International Codes&Standards,Pressure Vessel Code AS 1210Arc Welded Steel Pipe AS 1579Submarine Pipeline Code AS 1958Installation of UPVC AS 2032Installation of PEAS 2033Buried Flexible Pipelines Design AS 2566Gas&Liquid Pipeline CodeAS 2885GRP Pipes f
4、or Water&Sewerage AS 3571Installation of ABS Pipes AS 3690Pressure Piping Code AS 4041WSA 01 Polyethylene Pipeline CodeWSA 02 Sewerage Code of AustraliaWSA 03 Water Supply CodeWSA 04 Sewage Pumping StationsPIPA-OP010A:Part 1 Polyethylene Pressure Pipes Design for Dynamic Stresses,Power Piping ASME B
5、31.1Process Piping ASME B31.3Pipeline Transportation Systems for Hydrocarbons and other Liquids ASME B31.4Refrigeration and Heat Transfer Components ASME B31.5Building Services Piping ASME B31.9Slurry Transportation Piping Systems ASME B31.11Glass-reinforced plastics(GRP)piping ISO 14692-3Design&Con
6、struction of GRP Pipes BS 7159AWWA Fibreglass Pipe ANSI/AWWA C950,There are two categories of damage that arise from surge events,catastrophic failure of the pipeline system or equipmentfatigue failure of the pipeline,supports,instrumentation,equipment and components,Equipment and Processes Solution
7、s,Stronger pipework to withstand the pressure surgeRerouting pipingChange of pipe material to one with a lower modulus(i.e.thermoplastic pipe materials)Flow control valvesAir/Vacuum Release valvesIntermediate check valvesNon slam check valvesBypass ValvesGas accumulatorsLiquid accumulatorsSurge tank
8、sSurge shafts,Surge anticipation valvesRelief valvesBursting discsWeak pipe sectionsIncrease diameter of pipeline to reduce average velocityVariable speed drivesSoft startersValve closure and opening timesIncreasing the inertia of pumps and motors(i.e.flywheels or by selection)Minimising resonance h
9、azards and increase reliability by additional supportsInvestment in more engineering,Selection Process,Piping Design Using Stronger Pipe or Re-Routing the Pipeline,Use of Stronger PipeworkIncrease in capital costs for pipe,fittings,valves and instrumentsIncrease in velocity and celerity as wall thic
10、kness increasesIncrease likelihood of fatigue damage and maintenance costs if surge events frequentPipe inherently maintenance free compared to other surge devicesNeeds to be determined at design stage,Re-Routing PipelineIncrease in capital costsLand or easement acquisitionDirection drillingIncrease
11、d length of pipelineHydraulic grade line above the pipeline profile reduces potential for cavitationPossible increase in energyInherently maintenance freeNeeds to be determined at design stage,Change of Pipe Material to One with a Lower Modulus(i.e.thermoplastic pipe materials),Capital cost neutralN
12、ot a universal solution because of limited pressure classes availableThermoplastic pipe materials properties vary with temperature,strain rate and timeDoes not protect when column separation occursWall thickness selection to allow for vacuum conditionsLocal buckling at above ground supports to be de
13、signedNeeds to be determined at design stage,Flow Control Valves,Moderate capital costIncreased maintenance to ensure they remain effectiveCan be used for multiple duties and scenariosPower or instrumentation not necessarily requiredCan be retrofitted,Air/Vacuum Release Valves,Increased capital cost
14、sIncreased maintenance to ensure effective operationUse requires extensive modelling to ensure operation in all scenariosNot suitable for hazardous liquidsPrimary duty is for line filling and draining and hence location may not be optimal for surge mitigationNot all air valves are suitable for this
15、purpose due to their original designValve pit may be in road causing problems during construction or maintenanceCan be retro fitted easily if reducing tees in pipeline already installed otherwise tee type couplings required to be fitted,Modern Design of Air/Vacuum Release Valve-Ventomat,Intermediate
16、 Check Valves,Increase in capital costs for check valve but reduction in rating of other pipeline componentsEffective in splitting the surge pressure rise in twoDegree of increase in maintenance minimalProtects pumps from highest peak pressureNon slam check valves preferredValve pit may be in road w
17、ay causing traffic problems during construction or maintenanceCheck valves are not considered an adequate form of isolation and hence should be installed with isolation valvesNeeds to be determined at design stage otherwise pipeline needs to be out of service for retrofitting check valve,Non Slam Ch
18、eck Valve,Capital cost increaseFast closing valve reduces surge pressure at pumpReduces fatigue damageIncrease in maintenance lowInherently trouble freeAvailable as short or long patternUsed extensively in EuropeCan be retrofitted as valves standard lengths,Comparison of Check Valve Performance,Nore
19、va Annulus Type Non Slam Check Valves,Bypass Check Valves,Increase capital costIncrease maintenance to ensure effective operationNeeds positive pressure upstream to provide energy to fill cavitation voidsSimple and effective for overcoming negative pressuresDoes not provide protection for positive p
20、ressuresCan be readily retrofitted,Bladder Type Gas Accumulator,Increased capitol costsMaintenance level low for bladder type Provides secure protection for positive and negative surge pressuresBest located at source of pressure transient eventOverseas design and manufactureCan be retrofitted Long l
21、ead time,Hydro-Pneumatic Accumulator,Increased capital costsMaintenance level high for hydro pneumatic typeBest located at source of pressure transient eventProvides secure protection for positive and negative surge pressuresLocal design and manufactureCan be retrofitted if branched tees fitted to p
22、ipeworkLong lead time,Liquid accumulators,Increase capital costDifficult to model without test dataInherently maintenance freeCan be retrofitted but generally a long lead time,Surge Tanksand Surge Shafts,Commonly used in water transmission systemsProvides protection from negative pressure events but
23、 NOT for positive pressuresInherently maintenance free except for refilling facility of surge tankTelemetry required for monitoringCan be retrofitted but generally a long lead time required,Surge Anticipation Valves,Moderate capital costComplex devices Require power in the form of electric,hydraulic
24、 or pneumatic to operateDo not cover all surge events in a pipeline systemsHigh maintenance to ensure that they work when neededVendors who perform surge analysis and recommendation are NOT necessarily design engineers and do NOT take responsibility.Often do not have latest,or have limited capabilit
25、y,software.Can be retrofitted however moderate lead times,Relief Valvesand Bursting Discs,Increase in capital costConventional devices do not react quickly enough to prevent damage from surge pressureDo not protect against vacuum conditionsHigh level of maintenanceBursting discs require replacement
26、after operationNeed for registration and routine testing per CodeSuitable for lethal and flammable liquids as part of an overall protection strategyCan be retrofitted however may be moderate lead times,Weak Pipe Sections,Capital cost neutralReduces celerity in sensitive sectionsReduced surge pressur
27、e magnitudeReduced fatigue damageCould be damaged by vacuum conditionsSuitable for low pressure systems in the water industryInherently maintenance freeNot a universal solutionNeeds to be determined at design stage,Increase Diameter of Pipeline to Reduce Average Velocity,Reduced celerity and surge p
28、ressureIncrease in capital cost of pipe,excavation,valves and instrumentsIncreased life of the assetFuture augmentation possibleInherently maintenance freeReduction in energy of pumpingSettling of solids more likelyNeeds to be determined at design stage,Variable Speed Drivesand Soft Starters,Increas
29、e in capital costs and complexityLow level of maintenanceIncreased frequency of replacement and upgradeProvides NO protection for loss of power scenariosSoft starters protect power supply more than pipeline;there are NO guarantees they can be set to limit surge pressuresReduced fatigue issues for no
30、rmal stop/startLarger switchroom required to house devicesNeeds to be determined at design stage as costly to retrofit and to house in a switchroom,Valve Closure and Opening Times,Low capital cost solutionCan be effective in reducing surge pressuresRequires power supply in the form of hydraulic,pneu
31、matic or electrical energy to be totally reliableNeeds uninterruptible power supply for secure operationRequires extensive modelling to cover all operational scenariosRequires routine testing to be effectiveCan be modified during commissioning or operation if valves are automated and fitted with adj
32、ustable opening/closing devices,Increasing the Inertia of Pumps and Motors,Modest increase in capital cost Flywheels increase moment of inertiaFour pole speed motors and pumps have larger moment of inertia and have other benefits over two pole motor driven pumpsPhysically larger pump sets and hence
33、buildings may be increased in sizeInherently a low maintenance solutionNeeds to be determined at design stage,Minimising Resonance Hazards and Increase Stiffness by Additional Supports,Minimise ResonanceIncreased capital costsIncreased engineering to determine dynamic behaviour of pipingReduces dama
34、ge arising from dynamic loading and vibrationCan be retrofitted quickly,Improved StiffnessIncrease in capital costsReduction in peak pressure due to reduced celerityAcceptance of high fatigue damage causing increase in maintenance costsMore secure piping systemInherently maintenance freeCan be readi
35、ly retrofitted,Investment in More Engineering,a dollar spent at concept stage is worth ten dollars at design stageone hundred dollars at procurement stageone thousand dollars at fabrication stageten thousand dollars during construction and one hundred thousand dollars during commissioning one millio
36、n dollars once the lawyers are involved!“There always appears to be enough money to investigate a failure but never enough to do the design engineering in the first place”The Engineers Lament,But just a word from Lord Kelvin to temper the quest for an answer:,“Large increases in cost with questionable increases in performance can be tolerated only in race horses and fancy women.“Therefore your investment should be in engineeringoooooo-The End-oooooo,
