PIPELINES

OG 110 OIL GAS European Magazine 3/2008

Pipeline Technology Today and TomorrowBy T. CALLAN*

ransportation of liquid or gaseous hyd-rocarbons via buried cross-country pi-peline generally represents the safest

and most economic method of bulk move-ment of such products. In 2005 there existedworldwide a total length of over 1.5 millionkm of high pressure transport pipelines, notincluding water transmission pipelines orsmaller bore distribution networks. By 2030,this figure is predicted to almost double,with much of the increase due to the con-struction of new gas transmission and distri-bution pipelines.Historically, the development of pipelinetechnology has been driven by either techni-cal challenges, or by the need to reduce cost.Key influences today are:– Mitigation of environmental impact– Acceptance by the public and authorities– Competition with tanker transport (LNG,

crude).New applications, such as use of CO2 pipe-lines in carbon capture, transport and stor-age (CCS) projects, represent a new chal-lenge for the industry.This article reviews the current status of on-shore pipeline technology and makes somepredictions regarding future trends. The pre-sentation, which is an update of a similarstatus report prepared by ILF ConsultingEngineers in 2001 [1], follows the life cyclepath of a pipeline.

1 IntroductionThe first main oil and gas pipelines wereconstructed in the late 1800’s. Since thenover 1,500,000 km of high pressure trans-port pipelines have been constructed world-wide, not including water pipelines, flowand gathering lines and low pressure gas dis-tribution piping. This figure is expected todouble over the next 25 years, as existingfields are depleted and ever more remotesources are developed. Furthermore, the in-creasing energy demand in developingcountries such as China and India, as well asthe moves of established markets to diver-sify energy supplies, will drive the need fornew oil and gas pipeline transport corridorsto be constructed.The main historical factors driving develop-ment of pipeline technology have either

been to meet new technical challenges, suchas developing higher grades of steel to meethigher transportation pressures, and/or theneed to reduce cost.In recent years, the main factors driving de-velopment have been:– Mitigation of environmental impact, in-

cluding increased awareness of HSE is-sues. This has resulted for instance in thedevelopment of new methods and tools forrisk assessment and minimisation duringpipeline design, as well as implementationof sophisticated systems for leak detectionand monitoring of pipeline integrity dur-ing the life time of the system.

– Acceptance by the public and authorities,whereby this is an area that has sometimesbeen underestimated by the designer orproject owner in the past. The trend to-wards increased public awareness and sen-sitivity has been mirrored by the introduc-tion of new legislation, such as require-ments for more detailed Environmental &Social Impact Assessments of pipelineprojects, including public hearings prior toissuing authority approval of a project.

– Competition between pipeline transportand other options such as tanker transportof Liquefied Natural Gas (LNG) or crudeoil, which has been a continued incentiveto drive down pipeline costs.

Given the need for increased pipeline con-struction in the near future, it is useful to takestock of the current status of pipeline tech-nology and to analyse possible trends in theindustry. This review follows the main stepsin the life cycle of a pipeline following pro-ject conception, including: route engineer-ing, pipeline design and selection of materi-als, construction, operation and mainte-nance. Only onshore pipeline technology isconsidered in this review, whereby it is re-cognised that offshore pipeline constructionrepresents in itself a significant area of de-velopment.

2 Route EngineeringOne of the first main activities followingconception of a pipeline project is the routeengineering. This defines how to connectthe source, such as an oil or gas field, with asupply point, such as a tank farm or refineryfor liquids, or take-off point to a local distri-bution network for gas. Although the easiestand cheapest way to connect supply andsource is obviously via a straight line, in re-ality it is necessary to consider a large num-

ber of other constraints before being able todefine the optimum pipeline route.The most common practice today is to evalu-ate all these issues using GIS-based con-straint maps, of which an example is shownin Figure 1. The different colours representdifferent types of constraint, such as naturereserves or archaeological areas, land useplanning areas and geohazards.Typical considerations regarding constraintsinclude:– Constructability, for instance consider-

ation of the different type of terrain (geo-morphology) and soil conditions (geol-ogy) through which the pipeline must beconstructed. Rock conditions, may for in-stance be a constraint that leads to rerout-ing of a pipeline

– Safety of the route in regard to geohazards,such as seismic areas and fault crossings,areas of landslide, karst, erosion, liquefac-tion

– Minimum environmental impact, consid-ering water table (hydrology), local naturereserves, special flora and fauna, biotopes,etc.

– Minimum resistance from affected stake-holders, general public and authorities, forinstance, avoidance of inhabited areas andexisting infrastructure as far as feasible,and consideration of historical or archaeo-logical sites

– Finally it must be possible to acquire theright of way and easements required forconstruction and ongoing operation. Thisrequires detailed information on catastralboundaries, land use and zoning to assistin land acquisition negotiations.

In the last 10 years route engineering hasbeen revolutionized by the use of new map-ping technologies using GPS (Global Posi-tioning System) technology and use of satel-lite imagery and aerial photography. Fur-thermore, the development of GIS (Geo-graphic Information Systems) based sys-tems has allowed a huge variety of informa-tion to be digitally imported as backgroundlayers within the traditional pipeline align-ment drawings. In particular for constraintsmapping, it is possible to overlay informa-tion from a number of different sources ontoa single map and so find the “path of least re-sistance”.The availability of aerial flight, satellite andshuttle imagery has allowed further develop-ment of the so-called Digital Elevation orDigital Terrain Models (DTM). Such mod-els give a digital representation of ground

0179-3187/08/III© 2008 URBAN-VERLAG Hamburg/Wien GmbH

* Tim Callan, ILF Consulting Engineers, Munich/Germany(E-mail: Tim.Callan@ilf.com)

surface topography including geographicalfeatures such as vegetation, buildings andother infrastructure. Incorporation of thepipeline route into such a model is of greatvalue for the route engineering, allowing forinstance structural analysis of the pipeline,investigation of geohazards, flood anddrainage modeling, as well as preparation of3-D visualizations. It is noted that continu-ing improvements in the availability and res-olution of satellite imagery may in the futurenegate the current advantages of aerial sur-vey.Of course traditional on-ground terrestrialsurveying is still also necessary, in particularfor detailed design of special points such ascrossings, identification of third-party ob-stacles, as well as augmentation of DTMswhere necessary. New developments, suchas 3-D Laser scanning have improved the in-formation available and reduced the time re-quired for terrestrial surveying.By integrating imagery, as well as topo-graphical, environmental, land-use andcatastral layers, with supplementary tradi-tional survey data, is possible to generate allmaps and alignment sheets required forpipeline construction. The availability of allthis data in an integrated database simplifiesany revision that may be required, for in-stance due to re-routings. Finally, this forms

the basis of the Pipeline Information data-base that will eventually be handed over tothe Pipeline Owner/Operator to support op-erations and maintenance activities.One area of route engineering where there isstill the opportunity for development in thefuture is to find a similar cost effectivemethod for geological soil survey. Researchhas concentrated on infrared or radar-basedsurveys, but acquisition of data is still lim-ited to upper soil layers. Investigations areongoing into the use of seismic refractionsurveys and satellite data for this purpose.Finally, as already stated earlier, it is impor-tant during the route engineering to have anopen communication with authorities andthe public. As common-place as it now mayseem, the increasing use of the internet hasallowed a greater dissemination of informa-tion regarding potential pipeline projects,contributing to a general improvement in“public relations”.

3 Pipeline Design and MaterialsThe route optimisation exercise defines anoptimum pipeline corridor which may rangefrom 10 km to 100 m width, depending onthe stage of study and design. This gives theapproximate pipeline length which is thenused by the pipeline designer to define other

technical parameters of the pipeline, such asdiameter and pipe wall thickness. One of themain parameters that the pipeline designercan adjust is the grade of steel to be used. Asper the well known “hoop stress formula”,the higher the grade of steel, the lower thetheoretical pipe wall thickness necessary fora defined operating pressure. Lower wallthickness directly results in lower tonnage ofsteel that has to be purchased, transportedand welded.Over recent years, manufacturing improve-ments have resulted in an increase of theyield strength of pipeline steel commerciallyavailable, so that now API grade X80 is con-sidered a viable option for high pressurepipelines, with X100 already in trial opera-tion. Research is continuing into X120 gradeand it is expected that this grade will becomecommercially available within the next 10years. Welding procedures and consumablesmust also of course be developed to matchthe new materials.Table 1 highlights the advantage in using ahigher grade steel for a hypothetical trans-mission pipeline.Clearly large savings in steel tonnage arepossible. There is however a physical limitas to how thin a pipeline can be designed,based on manufacturing, handling and con-structability considerations. The generallyaccepted limit is that minimum wall thick-ness should not be less than 1% of diameter.This corresponds for instance to 10 mm wallthickness on a DN1000 pipe. Although thin-ner walled pipes have been and are beingconstructed, it is necessary to have verystrict control regarding handling, trenching,bedding and back-filling, in order to avoidproblems such as denting and ovality of theline pipe. Furthermore, manufacturing tech-niques for the higher grade steels may limitthe available minimum wall thickness: onepipe supplier, for instance, recommends aminimum thickness of 12 mm for X80 and16 mm for X100 pipe.Particularly for gas pipelines, there is an in-centive to increase the operating pressure incombination with higher steel grade [2].Figure 2 gives a set of curves showing the re-lationship between specific gas transportcost and annual gas throughput for a theoret-ical pipeline using grade X80 steel, compar-ing 56″ and 64″ pipeline diameter for variousdesign pressures. In each case the compressorstation pressure ratio (and hence number ofcompressor stations) has been optimised togive best efficiency. Specific transport cost iscalculated as the discounted cost of invest-ment (CAPEX) and operating / maintenance

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OIL GAS European Magazine 3/2008 OG 111

Fig. 1 Typical constraint map showing land use

Table 1 Steel tonnage for 1000 km pipeline90 bar operating pressure

Steel grade Tonnes

X52 856,000

X70 639,000

X80 560,000

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costs (OPEX) over 20 years. The curves con-firm that for higher transportation pressure,the potential throughput increases for a givenpipe diameter, while the specific transportcost reduces. For a “typical” intra-regionalgas transport volume of 30 BCM (billion cu-bic meters per year), for instance, the curvesshow that a 56″ pipeline operated at 140 barghas an economic advantage over a 64″ pipe-line operated at 90 barg. The 56″ pipelinecould optimally transport even 40 BCM at alower specific cost than the 64″ pipeline.One of the difficulties associated with highpressure cross-country pipelines is the abil-ity to get planning permission. A de-factolimit of between 80–90 barg maximum op-erating pressure seems to have become es-tablished in public and approval authorityperception (sometimes partly defined by in-country legislation), although there is nosignificant technical reason why this limitshould be the case. There is still a consider-able amount of technical justification re-quired in order to convince authorities andthe general public of the safety of high pres-sure pipelines exceeding 100 barg. In partic-ular, there is an increasing role for the use ofQuantified Risk Assessment (QRA) in orderto analyse risk scenarios, such as leakage,and to define mitigation measures in a trans-parent way.Over recent years, there has been further de-velopment in the use of computer models tosimulate pipeline hydraulics, as well as toanalyse pipeline integrity and safety. Use ofsuch computer models has also allowedmore detailed monitoring and control ofpipeline systems in operation. Particularlyfor crude oil and product transport, the accu-racy of on-line leak detection systems hassignificantly improved over recent years.One application of such software modelsduring the planning stage is the analysis ofenvironmental risk. Figure 3 shows the typeof considerations that can be made for acrude oil pipeline for instance. The bottomaxis shows the pipeline profile and locationof block valve stations which may be closedin case of pipeline leak. The other axes showvarious factors such as potential leak quan-tity at each location, as well as location-spe-cific sensitivity factors such as: ground wa-ter; land use; archaeology and so on. The topaxis shows the environmental risk calculatedas a factor. By placing block valve stations atoptimum locations it is possible to minimisethe overall environmental risk factor.Use of sophisticated non-linear finite ele-ment models to investigate geohazards suchas active seismic faults and splices has im-proved design of such crossings, whilst atthe same time allowing to minimise con-struction costs.Furthermore, pipe sections are now almostalways provided with factory-applied highresistance tri-laminate coatings. When ahigh quality coating is combined with an im-pressed Current Cathodic Protection (CP)system in an installed pipeline, the possibil-

OG 112 OIL GAS European Magazine 3/2008

Fig. 3 Environmental risk assessment based on theoretical leak quantities

Fig. 2 Comparison of specific transportation cost for a gas pipeline atdifferent operating pressures

ity of external corrosion is virtually elimi-nated.Internal corrosion, however, is still a prob-lem, especially for applications such asmultiphase flow lines. Use of exotic steelssuch as duplex is becoming more common;however, there exists the potential for furtherresearch and optimization of the metallurgyin order to improve corrosion resistance.New pipeline applications, such as transpor-tation of supercritical CO2, or of highly cor-rosive substances such as liquid sulphur,also provide a challenge for the corrosionengineer. For such specialist applications, itis vital that the chemical composition of thetransported product is exactly defined, con-sidering potentially harmful contaminants.

ConstructionOne of the major costs of establishing a newpipeline is the construction cost. Over thelast few decades there has been relatively lit-tle innovation in the construction methods ofonshore pipelines, except in a few key areas.One of these is the development of new tech-niques for constructing crossings, such ashorizontal drilling (HDD) and micro-tun-neling. The limits of HDD have in the mean-time been extended to greater than 1000 mfor 56″ pipe diameter. Other techniques havebeen developed allowing simultaneous tun-nelling and thrusting of the prefabricatedpipeline into the drill hole (e. g. DirectPipeTM), further reducing time and cost forsuch crossings and at the same time reducingthe risk of execution.In regard to pipeline construction, manualarc welding is still the most commonmethod. The use of mechanised or auto-mated welding combined with ultrasonictesting has increased, although, use is proba-bly not as widespread as many would havepredicted. Laser-based welding techniquesshow some promise, but are still in the devel-opment stage.Finally, there have been some innovations inthe area of trenching equipment, such asauto-trenchers and “No-Dig” systems.Many of these systems may still be consid-ered to be under development.Considering the future, great efforts are un-derway to reduce the cost of pipeline con-struction. One application for the construc-tion of large cross-country pipelines in rela-tive easy terrain is the use of the so-called“Land Lay Barge”. This is based on the off-shore approach where all activities such asdouble-jointing, welding, NDT and layingare combined onto a moving platform (i. e. aship in case of offshore construction). Fig-ure 4 shows an illustration of a typical landlay barge configuration.The land lay barge concept aims to concen-trate the logistics of ROW clearing, trench-ing, pipe stringing, welding, NDT, loweringand back-filling into the most compact areapracticable. Operations, which on a typicalpipeline construction site may be offset by

several weeks, are timed to occur ‘just-in-time’ for the subsequent constructionstep. In particular, the co-location of joint-ing, welding, NDT and coating operationson a single moving platform eliminates alarge amount of equipment logistics andmovement of personnel.Use of such lay barge techniques, however,is generally limited to relatively flat and un-obstructed terrain, where it is not necessaryto frequently dismantle the barge in order totraverse crossings or to circumvent other ob-stacles. For more complicated routes incor-porating steeper slopes, the traditional sidebooms are still used, whereby there havebeen some developments in the manoeuvra-bility and operability of these units in recentyears.Furthermore, it is clear that the trend of in-creased HSE (Health, Safety, Environment)requirements will continue, giving associ-ated improvements in construction safety,but also coupled with increasing compliancecosts.The new pipelines will be constructed in evermore remote areas, with difficult terrain andadverse weather conditions. Associated in-frastructure, such as compressor and pumpstations, must also be planned with the pipe-line systems. Many of the aspects mentionedabove relating to the pipeline itself, such asselection of optimum location, analysis of en-vironmental risk, etc. also apply to the associ-ated stations and facilities.GIS technologies, as already mentioned forroute engineering, are also now already im-plemented during the procurement and con-struction phases. Pipe tracking systems al-low monitoring progress of single pipelengths from mill to welded location in thepipeline and can be later integrated intooverall Pipeline Information ManagementSystems (PIMS).

5 Operation and MaintenanceAs for route engineering, modern informa-tion technology has lead to major advances

in the operation and maintenance phase of apipelines lifetime. Use of hydraulic simula-tors, leak detection systems and GIS-basedemergency response plans are just some ex-amples.Implementation of on-line monitoring sys-tems allows the Operator to obtain more de-tailed information in regard to actual threatsor events impacting pipeline integrity thanhave been achievable by traditional visualROW surveillance methods. Use of suchsystems is becoming more critical, consider-ing the growing present-day threats of illegaltaps, intentional sabotage and terrorism.Several such systems exist, one example be-ing the use of acoustic sensors mounted ontothe pipeline at regular intervals to monitorand localise impacts on the pipeline itself oreven within the right-of-way.For new pipeline systems, considerationmay be given to co-laying special Fibre Op-tic Cable (FOC) in the pipeline trench. Inthis method, the FOC is used as a continuoussensor to monitor small changes in tempera-ture, strain or acoustic footprint. Eachmethod relies on the fact that a change inconditions will cause light transmissionalong the cable to be disrupted. Leaks orother incidents can be accurately pinpointedby monitoring the timing of reflectionscaused by this scattering of light. It shouldbe noted that the location and method ofFOC installation in relation to the pipe iscritical, depending on the transported me-dium and leak characteristic or deformationto be expected.Other advances in terms of operation in-clude the use of flow improvers to increasetransport capacity through existing oil pipe-line systems. In a current project, for in-stance, it is predicted that a 60% increase inthroughput can be achieved through an ex-isting crude oil pipeline system by using newgeneration suspension-based Drag Re-ducing Agents.Although intelligent pigs have been used fora number of years, the type of informationthat can be obtained by such methods is in-

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OG 114 OIL GAS European Magazine 3/2008

Fig. 4 Typical land lay barge configuration [3]

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creasing. Information from intelligent pig-ging is one aspect of a detailed monitoringand inspection programme that can be im-plemented even for quite old existing pipe-line systems. In a number of recent projectsin Germany, for instance, it has been possi-ble to demonstrate the integrity of pipelinesystems built in the 1960´s to the satisfac-tion of the respective Authorities, allowingextending the operating permits of such sys-tems.As mentioned above, GIS-based systems arenow implemented to support operations andmaintenance activities. Such systems inte-grate physical and geographical informationabout the pipeline assets with real-time in-formation and embedded organisationalprocedures. Graphical tools provide a user-friendly interface for quick and easy accessto information.

6 Perspective for the GasSectorIt is apparent that the pipeline market willdevelop significantly over the next fewyears. In Europe, there are several strongfactors driving activity, particularly in thegas transport sector.A number of recent incidents have increasedawareness of gas supply security. Of thethree main gas sources currently supplyingEurope, the North Sea reserves are declin-ing, while supplies from Russia and sub-Sa-haran Africa have their own security issues.Although Germany in particular seems to bebuilding up its reliance on Russian gas viathe Nord Stream pipeline, it is the stated aimof the EU to diversify gas supplies to Eu-rope. This will mean building large intra-re-gional pipelines from the Middle East, Asiaand Africa. The dashed lines on the map inFigure 5 show some of the well-known pipe-

lines that are currently in various stages ofplanning (e. g. Nabucco, SCP-Expansion,Trans-Adriatic, Trans-Arab, Trans-Cas-pian).Liberalization of the European gas market,including common carrier and free accesslegislation, should theoretically lead to fur-ther interconnection of individual countrynetworks. Furthermore, the continuing de-velopment of LNG in order to diversify sup-ply, as well as increased underground gasstorage for security purposes, will also re-quire the construction of new gas pipelinesto interconnect the new terminals and stor-age facilities to transport infrastructure.A new application is the predicted future in-crease in installation of CO2 pipelines, usedto transport carbon captured from fossil-fuelpower stations and other industrial plants tounderground storage reservoirs. A signifi-cant safety aspect associated with such ap-plications is the potential contamination ofCO2 with impurities such as H2S and SO2

which could lead to a health hazard if re-leased. Here there is a need for detailed riskanalysis to evaluate potential leak scenariosand define mitigation measures.In conclusion, there have been some signifi-cant developments in pipeline technology inrecent years. Further innovation is continu-ing in order to meet the technical demands ofa growing sector, while at the same timedemonstrating the ongoing safety and envi-ronmental acceptability of this technologyto the general public.

References:[1] A.H.Feizlmayr, ILF Consulting Engineers, C.Mc-

Kinnon, J. P. Kenny: Pipeline Technology Ad-vances. Oil & Gas Journal November 26, 2001volume 99, issue 48.

[2] L. Bangert, ILF Consulting Engineers: Engi-neering New Limits for Large Gas TransportationSystems. 3R International, Special 1/2006 Pipe-line Technology, p. 5–7.

[3] H. Schirm, ILF Consulting Engineers: Land LayBarge Technology Review; BP-IPLOCA: 2004Athens Steering Group, Presentation09. 11. 2004.

Tim Callan received a Mastersof Engineering Degree (Me-chanical) from Auckland Uni-versity, New Zealand in 1985.After working for five years as aconsultant on energy projectsin New Zealand, he relocated toGermany, where he joined ILF

Consulting Engineers in 1990. He has accumulatedmore than 23 years experience as a consultant in thePetrochemical and Energy sectors with particularemphasis on pipeline projects and associated infra-structure. He has been responsible for a numberof large-scale pipeline projects, including from 2001to 2005 as Engineering Manager for the Turkish sec-tion of the BTC Oil Pipeline. He is currently Depart-ment Manager Oil and Gas Pipeline Systems for ILF inMunich.

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Fig. 5 Current and future main gas flows to Europe