hdd applications in pipeline projects in europe · pdf filetrenchless technology 1 3r...

Trenchless Technology

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3R international · Special-Edition 2/2007

HDD applications in pipeline projects in Europe

By Dr. Hans-Joachim Bayer and Dott. Ing. Giacomo Bandera

Essential Horizontal Directional Drilling (=HDD) in pipeline projects

Rigs for horizontal directional drillings arenowadays part of pipeline constructionprojects and are among excavators, hoistingcranes and other common auxiliary tools.This ever increasing trenchless technologycontributes a technical and economic edgeas well as providing environmental and pro-ductivity advantages. The main applicationsfor HDD pipeline projects are under-rivercrossings, traffic way crossings (canals, rail-ways, highways, roads, runways, etc), floodprotection dams, crossings below founda-tions of buildings or infrastructure objects,shortenings through topographic obstacleslike rock ridges, orthogonal situated hills andrims, non-crossable terrains and e.g. under-crossings of nature reserves, parks or evenhole city areas or mountain zones. HDD rigsof different size and type are used for pipe-line installation projects of differing lengths,depths, curves, geology as well as technicaland environmental conditions.

Range of HDD machines

There is a wide spread range of HDD ma-chines for the trenchless market, rangingfrom a 1.5 tons pit machine to a 550 tonsmega rig. The principle of the directionaldrilling process remains the same howeverthe pulling force of this HDD machines dif-fers by a factor 1:300. HDD machines in the1.5 t to 4 t-class are only used for house con-nections and street crossings.

Horizontal directional drilling units most fre-quently required are those in the perform-ance range of 7 t to 20 t thrust and pullingpower as these units are very well dimen-sioned for standard pipe installations in res-idential areas and city centres. Smaller units(7–10 t-class) are often used for longerhouse service connections or in very restrict-ed environments, while the larger units areemployed for installing drainage pipes,

smaller dimensioned under-river crossings,environmental or geotechnical bores as wellas small pipeline and sewer pipe installa-tions. As a rule, the specialist company willalways select the equipment best suited forthe project after consulting with the custom-er.

For installing pipelines over longer distances(middle to high pressure pipelines) HDD ma-chines from the 35 t-class up to the biggestunits existing in the HDD market are re-quired. Nearly all obstacles along pipelinetraces like rivers, lakes, mountain ridges,traffic lines such as railways with highwaysand roads can be overcome with the HDDtechnique, thus open river crossings or opencrossings of traffic lines get out of use for en-vironmental and economic reasons. All long-distance pipeline projects in Europe andNorthern Asia have an essential need forHDD crossing jobs under natural and artifi-cial obstacles. An overview of such HDD ap-plications in pipeline projects is presented inthis paper.

HDD for under-river crossings

Underwater crossings (of rivers, canals,lakes) which would otherwise require a spe-cial construction effort, can be executed us-ing the trenchless HDD method in the sameway sections can be installed in the normalroute of roads. Underwater crossings areparticularly advantageous because no spe-cial ground water retention is required thatnecessitates other structural preparationmeasures; only the bore path is steered in acurve under the obstacle. Overground andcombined underwater crossings are HDDstandard applications. A great number ofthem are performed every day.

In pipeline projects the jobs get divided insections of open trenching and sections ofunder water crossings and crossings trafficways and other obstacles. Nowadays, nor-mally all underwater crossings are plannedand projected for HDD machines. The selec-tion of the machine’s power class depends

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on the depths and the lengths of existing wa-ter obstacles, the geological underground inrelation to the diameter and the weight of thepipe section. Often various HDD machinesare working at different spots and with differ-ent crossing tasks for the same pipelineproject. The longest underwater crossingswere done in 2004 and 2005 when crossingthe river Wolga in the river Elbe at a lengthof 2.2 and 2.6 km. River crossings in Europeare primarily done in the summer or wintertime because in the springtime rivers oftenare flooding. In Siberia river crossings areprimarily executed in winter time when thepermafrost ground is frozen and the riversthemselves are covered with a load resistantice crust which made it easy to transportingequipment like rods and tools from the oneriver side to the other. This offers a logisticadvantage. On the other hand the drilling rigmust be covered with a thermo tent so thatdrilling operations even below minus 30 ºCcan be performed.

The preferred pipe material is steel and pro-tected steel (concrete cover, polyethylenecover), mainly for oil and natural gas pipe-lines. Cast iron pipes and PE pipes are oftenused for sewers whereas PE and steel pipesare preferred for water transport pipelines.Due to the weight of the pipes for long underwater crossings the machine choice tens to-wards more powerful HDD units. In recentyears a couple of river crossings were donethrough rock because the mud motor tech-nology enables to penetrate all kinds of geo-logical conditions. A major challenge forHDD under-river crossings is the permanentchange between hard and soft rock layersbelow the river bed which are to be found inall rivers coming from high mountain ranges.These rivers have rocks and boulders, roughgravel and pebbles between fine grain mate-rial in their ground and the drilling underthese conditions needs experience and feel-ing for the ground conditions. Anyway, thenumber of under-river crossings in this chal-lenging geology is increasing, more andmore experienced HDD companies success-fully carry out impressive crossing jobs inthese ground conditions.

Thanks to HDD, the majority of all crossings,and under-river crossings is carried out us-ing this trenchless method with a trend to-wards trenchless installations growing toover 90 % particularly over the past fewyears. Many companies have meanwhilespecialised in such applications and performthem exclusively. Thanks to the rock drillingtechnique using low-flow mud motors thereare no longer any soil conditions that cannotbe coped with by drilling. The only thing thatneeds to be done is to select the optimumHDD system size, the optimum drilling fluidfor the type of soil and the best suitable boretools and steering equipments.

Rivers and lakes with depths of 200 m oreven 300 m can be crossed using 20 t-borerigs. Using maxi and mega bore rigs, riversand lakes more than 2,500 m wide have al-ready been bored. The dimension of in-stalled pipes has already reached walk-through diameters. Mega rigs have especial-ly been built for large-scale crossings andunder-river crossings, rock drillings and largeinfrastructure projects. The demand for verypowerful mega rigs is increasing and rigsabove the magic 500 t-class will be con-structed mainly for large under-river or underlake crossings for pipeline installationprojects.

Rhine river crossing in Alpine Boulders in Basel, Switzerland

The river Rhine flows through a relativelynarrow and deep bed in the municipal areaof Basel, with buildings and traffic ways onboth sides and in immediate vicinity. In everysense of the word, Basel is “closely” con-nected to the Rhine, which changes direc-tions from the “Alps Rhine” to flow as the“Upper Rhine” to the north. This gate posi-tion results in a pile up of gravel, blocks andboulder material 17 m below the river floor.Many boulders have a half meter and evenmore in diameter and they consist of natu-rally transported material from the centraland the northern Alps. Underneath lie solidclay and sandy marl layers in close succes-sion with gravel and boulder layers whichhave completely opposite characteristics asfar as drilling techniques are concerned.

A large chemical manufacturer commis-sioned a Swiss building contractor to installa network of empty PE-pipes underneath theriver Rhine to host fibre optic communica-tion cables and chemical product pipes. Asection of the required installation was theundercrossing of the river at a depth of 24m.

In awareness of these difficult ground condi-tions, the contractor choose a 50 t-drillingunit from Prime-Drilling, particularly becausethe length of the undercrossing was to be400 m. The 50 t-rig was an excellent choicefor this job, because of its good drilling abil-ities, even taking the difficult undergroundand the confined space into account (FFFFiiiigggguuuurrrreeee1111

). Beside the PD 50/33, a recycling systemwith a flow rate of 1,000 litres of drilling fluidper minute was used. The machine wasequipped with a mud motor bearing a 200mm drill head with TCI-bits for the gravel andstone layers and mill tool bits for the pilotbore through clay stone and sandy marl be-low at a depth of 17 m. The roller bit headhad to be driven out and exchanged fourtimes during the pilot bore because of theconstantly alternating geological conditions.Several days of work were required for the pi-lot bore. The first upsizing bore was carried

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out with a 350 mm hole opener with TCI-bits, while a hole opener with a diameter of450 mm was used for the second reamingoperation. A third check reaming followedwith the 450 mm hole opener and a fly cut-ter attached to the rear. The 355 mm hostpipe was pulled into the 450 mm bore holeas a final working step.

The whole project in this difficult under-ground and limited space on the factory sitewas finished within six weeks including a riv-er crossing at 24 m depth and the completecable installation.

Gas pipeline project near Torino, Piemonte, Italy

A very impressive job site was completed in2006 in the Alpine foreland northeast of Tori-no. Near the city of Chivasso, the Orco riverhad to be under crossed over a length of1,249 m for a 660 mm steel pipeline for nat-ural gas. The Orco river, directly comingfrom the Gran Paradiso Mountains in theGraie Alps (reaching 4,061 m altitude) is a“wild river” with a high transporting energyand with sudden water level alterations witha frequent danger of flooding (FFFFiiiigggguuuurrrreeee 2222

). Riv-ers from the high mountains have roughgravel below their river bed, mainly a wildmixture from boulders to sand.

Several days of work were required for ream-ing steps and a special reamer was built tocarry out hole expansion with a 900 mmhole in very difficult underground. In thisproject the fly cutter was not used to cleanerhole for presence of big gravel and boulders(size: diameter from 60 mm to 120 mm upto 8.0 m depth). In pipe site big trench wasmade and a lot of gravel was removed toeliminate critic soil and favour pullback. Inthis site during drilling activities an othervery big trouble was phreatic surface butpumps system was implemented to dry thetrench.

The HDD drilling job was well done by the ex-perienced pipeline construction companyGhizzoni S.p.A. with their 460 t-Prime Drill-ing rig, and even under winter conditions(FFFFiiiigggguuuurrrreeee 3333

).

Jobsite details:Year of project: 2006Customer: Snam Rete Gas

S.p.A.Gas pipeline project: Bellinzago – TorinoMaterial: EN L415 MB – API 5L

X60Pipe OD: 26” (660 mm)Wall thickness: 15.9 mmLength: 1,249.1 mMinimum bending radius: 1,063.7 mEntry point angle: 9°

Exit point angle: 9°Pressure: 60 barUpsizing bore: 36” (900 mm)Site: Chivasso (TO)Crossing: Orco RiverSoil type: Sand & gravelRig: Prime Drilling 460 t

Gas Pipeline project near Vibo Valenza (Valentia), Calabria, Italy

A huge pipeline project in the very south ofItaly with a 48” natural gas pipeline was re-alised in 2005 by the very experienced com-pany Ghizzoni S.p.A. with their 460 t-PrimeDriling rig. The Mesima river, coming fromthe Appennino Calabrese, was crossed threetimes in different pipeline sections. Step bystep bore hole reamings up to 1,600 mmwere created at this job site, which areshown in FFFFiiiigggguuuurrrreeee 4444,,,,

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The first expansion (pilot bore) was carriedout with a 250 mm hole opener with milledtooth bit, while a barrel reamer with a diam-eter of 600 mm was used for the secondreaming operation. Other check reaming fol-lowed with the following barrel reamer: 900mm 1,200 mm 1,400 mm.

The last check reaming followed with the1,600 mm barrel reamer and a fly cutter at-tached at the back.

The 1,200 mm host pipe was pulled into the1,600 mm bore hole (30,9 % Over Cut) as afinal working step.

A lot of side-booms and rollers were usedduring pullback to make stable the pipe andan over bend was realized with the 1,200 mradius.

The work was completed in 2005 undersouthern temperatures to the complete sat-isfaction of the customer.

Jobsite details:Realisation year: 2005Customer: Snam Rete Gas

S.p.A.Gas-Line: Palmi – MartiranoOD pipe: 48” (1,200 mm)Wall thickness: 18.9 mmMaterial: EN L455 MB – API

5L X65Pressure: 75 barBorehole reaming: 62” (1,600 mm)Rig: Prime Drilling 460 tMesima River crossings:

a) from 8th to 9th pipeline sec-tion (Rosarno-Serrata) – length550.0 m – min. radius 1,490 maboutb) from 10th to 11th pipeline sec-tion (Rosarno-Serrata) – length530.0 m – min. radius 1,500 mabout

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c) 12th pipeline section (MesimaRiver) – length 480.0 m – min.radius 1,600 m about

Soil type: Silt - Sand – Gravel

Undercrossing the Alp Lake in Allgeau Alps, SW Bavaria, Germany

The Alp Lake is located 725 m above sea lev-el in the west of Immenstadt in the AllgeauAlps between Lake Constance and Tirol (Ty-rol). The mountains north of the lake reachan altitude of 1,100 m, south of the lakemore than 1,800 m. The Alpsee itself has aneast-west length of about 4 km and a north-south reach of maximal 1,100 m. The maxi-mum depth of the lake is 24 m. The geologybeside and below the Alpsee is determinedby layered sequences (Tertiary), on the lakeground moraine material is sedimented.

The city of Immenstadt had the duty to builta ring sewer system around the lake, with560 m of gravity pipes, 9,100 m of pressurepipes, 35 pumping stations and the neces-sary equipment. A 2,300 m section of the9,100 m pressure pipeline has to be in-stalled below the lake ground, with the mostpretentious task being a north-south lakecrossing of 600 m length in the western andsmaller part of the lake. The depth of theAlpsee is 16 m there, the pressure pipe hadto be positioned at minimum 3 m below thelake floor.

The city of Immenstadt assigned the experi-enced company Max Wild from Illerbachenfor this lake crossing for. Max Wild used aGrundodrill 20 S HDD unit from Tracto-Tech-nik and even a small boat for navigating thedrill head from the water level. The pilot borewas done with a soft rock drill head becausethe ground moraine and the following chang-ing layers allowed for this method. Boulderswere overcome and a path was drilled suc-cessfully without interruption in one day andthe following night. The first reaming step to-gether and pulling in the pipe from the otherside of the Alp Lake was also done in oneday and one night. The effective lake cross-ing distance was 650 m, the longest lakecrossing in the Alps, carried out with a 20 t-drilling rig in an extremely short drilling timeleaving a very content and impressed cus-tomer.

HDD for crossing traffic ways

Especially when undercrossing traffic wayslike railways, highways, roads, streets, run-ways etc. pipelines have to be embeddedsafely and with stability in the existing under-ground infrastructure. Using the sophisticat-ed HDD method it is possible to drill small tolarge diameter boreholes and keep theseboreholes and the surrounding undergroundstable during the pilot boring or during ream-

ing for the embedded pipeline later. With theHDD pilot process, there is normally no un-steered or non-surveyable moment, so thedrilling head is under permanent navigationand positioning control. This is very impor-tant with regards to underground infrastruc-ture safety and it is an important advantagein comparison to non steerable or uncontrol-lable methods. HDD crossings do not inter-fere with the underground, structure and thedrilling fluid is a smooth transport mediumssafely embedding the cuttings of soft or hardground. Using wireline systems for detectionavoids accidents has operators don’t have towalk over busy streets. HDD has the enor-mous advantage that neither manhole haveto be built nor groundwater control is re-quired during the installation.

Bore under a runway at Airport Friedrichshafen, Germany

The airport Friedrichhafen-Löwental nearLake Constance was founded 1913 and is anairport, for airships (zeppelins) and regularaeroplanes. When a second hangar for theairships was built, a water pipeline connec-tion between the aeroplane maintenancebuilding of and the new airship hangar be-came necessary. The complete plane run-way had to be under crossed over a distanceof 450 m (FFFFiiiigggguuuurrrreeee 7777

). A soil investigation tookplace primarily along the bore path. The ge-ological survey indicated that the airportarea is situated in an old, completely siltedsea with flat valley sediments. It was decidedto used the Grundodrill 20 S HDD rig, a 20t-unit. In the runway area, drainage and sew-age pipes of various diameters laying at dif-ferent depths parallel and orthogonal to therunway had to be considered leaving a cross-ing depth of 5 m. Due to aviation safety re-strictions walking over the runway to detectthe pilot bore was only permitted a few hoursduring the night.

The experienced bore crew of company MaxWild from Berkheim realised this in a shorttime. The upsizing bore was done twice, thelast step with a 480 mm reamer. The borechannel was completed to perfection, so aHDPE protection pipe with 355 mm diame-ter and a total weight of 11.7 t was pulled inwith the Grundodrill 20 S. The pipe pulling-in process took 16 hours. Then the 225 mmwater pipe type SDR 11 PE 100 was pulled inwith the bore rig taking roughly 15 hours, be-cause every 2 m plastic skids had to be as-sembled, which disturbed the continuouspulling-in process. Just 14 days after com-pletion of the bore the drinking water pipe-line was taken into operation. The jobsitewas cleared after 5 days as required, thanksto the careful planning and professionalcompletion.

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With HDD through the mountains

The use of trenchless technologies for bothnew pipe installations and the pipe renewalin hillsides provides beneficial advantages.Expenses that are typical in classical civil en-gineering, such as special walking excava-tors, safety measures supporting the slope,special sheeting, safeguarding of the exca-vated soil, bracings in the trench, specialand difficult compaction work when backfill-ing the excavated soil on the slope and com-plex landscape conservation work can becompletely avoided. With the same equip-ment which is used for horizontal directionaldrilling to install pipelines or to under crossrivers, roads and railway embankments,house connections in hillsides can be”drilled through”. Costs are about the sameas for bores in flat terrain. The additionaldepth in difficult soil does not constitute anyadditional expenditure. By installing newpipes using the trenchless method, gardenvegetation that has been carefully cultivatedand cared for is preserved without damagingthe soil structures of the roots. In critical hill-sides that often require a renewal of pipeswith flexible plastic pipelines due to theamount of swelling clay minerals in the soil,trenchless construction methods offer addi-tional advantages that can have moderatingand stabilising effects on the slopes.

Shortening through the Swiss Jura mountains near Reigoldswil

Reigoldswil is located in the canton of Basel-Land and embedded in folded Jura moun-tains which reach the altitude of 900 to1,200 m. A natural gas pipeline, existingsince 1967, had to be replaced and deviatednear the village area of Rappertswil. The newsection of the steel pipeline to be replacedwas 900 m in length, now situated fartheraway from the next buildings. The networkowner, the Gasverbund Mittelland AG, decid-ed to cross within a mountain ridge over alength of 460 m. The mountain ridge “Berg-li” consists of a typical Upper Jurassic se-quence with hard limestone and weak marlsin frequently changing layers.

For realising the project in summer 2005,first a small street up the mountain hillsidehad to be built for transporting the 100 t-Prime Drilling HDD unit to its starting place(FFFFiiiigggguuuurrrreeee 8888

). The experienced drilling companyBohlen & Doyen from Germany, owner of the100 t-Prime Drilling unit, established the pi-lot bore with a mud motor equipped with a250 mm roller bit. Control of the bore wasrealised using an artificial magnet field inthe drilling area and a detection system be-hind the bore head a wireline inside the drillrods connected to the control board of themachine.

The drilling process in the Jurassic layers re-quired constant adaptation of the drilling flu-id mixture due to the strata dominance in thebore hole. The complete drilling fluid was re-cycled on site. The second working step wasto upsize the borehole with a 500 mm holeopener. The third step was to pull in thewelded steel pipe Ø273 mm into the bore-hole, which was filled with a enriched drillingfluid.

The job site was finished exactly in the giventime, the customer was very content andused reports on this jobsite for promotionalpurposes in Switzerland.

Possibilities for geotechnical investigations for tunnel projects

Using controlled HDD, geological investiga-tions in the future can be made for planningprospective tunnel routes (one example isthe new Mont Blanc railway tunnel). In doingso, liquid probing and solid rock probing us-ing certain instruments can be achieved. Inaddition, geotechnical instruments can beinstalled. HDD boreholes can also be usedfor geophysical investigations. With the helpof several parallel but vertically and laterallyraised boreholes, investigations in the bore-hole can be performed by means of geo-physical instrumentation which provide geo-physical 3D surveys of entire sections ofrock, i.e. detailed three-dimensional investi-gation.

These investigations are of particular impor-tance if tunnel sections run through swellingrock (e.g. anhydrite, swelling clays), throughtectonically weak zones or mellow rock hori-zons, through banking layers or anomalies.

Tunnel improvement

Many older tunnels were directly cut out ofrock. They have no inner shell and some-times mains and services supply lines areunder capacity. As a result of new fire pro-tection regulations in tunnelling, additionalfire mains, for instance, can be installed withHDD rock drilling and delivery pipes for firefighting water can be laid on the tunnel floor.Bores for additional ventilation and air ex-traction as well as pilot bores for rescue tun-nels and crossovers can be realised withHDD: Moreover, consolidation in friable oldtunnel sections, for example, is possible withconcrete injections using HDD.

Advantages of HDD applications

The most striking advantage is the preserva-tion of the traffic way or ground surface asstatic/dynamic supporting structure. Thenatural structure of the soil above the pipe-installed underground is completely pre-

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served. An even ground drilled in duct formbased on optimum static calculation andpreserved in its cohesive soil structure en-sures even static loads above and aroundthe pipe so that point loads are completelyavoided with firm pipe embedding alreadydiscussed. The pipe is installed in a roundborehole. Due to the cylindrical geometry ofthe borehole or the micro tunnel, respectivetensions in the soil will be diverted almostideally around the cylinder in arch form, asthe untouched superstructure has a verystrong supporting effect. Complete filling ofthe annulus between pipe and cylindricalhollow body ensures an even better diversionof the mechanical line of tension in the soil.Compressive strain and tensile stress are rel-atively balanced. If pipes are covered in ac-cordance to regulations, the load on the pipeis definitely lower than with open construc-tion.

As the removal of excavated soil and thetransport of the above mentioned resourcesare kept to a minimum, residents will not beannoyed as a result of high traffic and noiseand there will be no obstructions of trafficand entries. A construction site that is al-most independent of weather conditions alsoallows high working speeds so that only afraction of the time (only a quarter in someinstances) will be required for trenchlesspipe installation work as compared to opentrenching.

In trenchless construction, installationdepths have no influence on the cost sincethe only cost determining factors are boringand backreaming. The installation of pipesto be laid at great depths can be carried outespecially cost effectively using horizontal di-rectional drilling.

With horizontal directional drilling usingmega rigs, bores under busy traffic routes(roads, railways, waterways, runways fortake-off and landing) do not cause any short-term traffic restrictions; with standard drill-ing technique there will only be very short-term and almost selective obstructions dur-ing detection of the pilot bore. As this is anongoing process, traffic restrictions are nor-mally limited to a few minutes only.

In hillside locations where any conventionalopen trench installation requires special ef-fort and expense, horizontal drilling works atnearly the same bore speed as in even ter-rain.

Under valuable flora and fauna, in parks, un-der rows of trees or habitats, horizontal di-rectional drilling does not impair the naturalcover in any way as roots can always becrossed without any problem and without ad-ditional cost. The same applies to plants onriverbanks when crossing under-rivers.

Horizontal directional drilling with mega rigs,moreover, allows major transmission instal-

lation measures in a most expedient way,but also inner-city pipe installations of largerdimensions and higher pipe weight are pos-sible. Product pipes made of heavy material(ductile cast iron, steel, thick-walled PE orPP) as well as installation lengths at severalmeters in depth or heavy, even rocky subsoilcan be most expediently handled by megarigs and are much more attractive both froma technical and economic standpoint ascompared to open trenching. Especiallywhen installing gradient drainage pipes char-acterised by considerable depths, employingthe HDD method using mega rigs - even inless densely populated areas and for new de-velopments of residential areas - is attrac-tive, since the lower degree of technical andecological complexity usually translates intolower cost.

Literature

[1] Arnold, W.: Flachbohrtechnik, S. 968, Leipzig/Stuttgart: Deutscher Verlag für Grundstoffindus-trie, 1993

[2] Bayer, H.-J.: Das steuerbare Horizontalbohrver-fahren in der Versorgungs- und Umwelttechnik,bbr (1989) Nr. 6, S. 331-335

[3] Bayer, H.-J.: HDD Practice Handbook; 196 p.,Essen: Vulkan-Verlag, 2006

[4] Fengler, E.-G. et al.: Grundlagen der Horizontal-bohrtechnik (Herausgeg.: LENZ, J.), Iro-Schrift-reihe Nr. 13, 229 S., Essen: Vulkan-Verlag, 1998

Internet links

[5] Manufacturer’s information provided by Tracto-Technik GmbH, Lennestadt

[6] Manufacturer’s information provided by Prime-Drilling GmbH, Wenden-Gerlingen

Dr. Hans-Joachim Bayer

New applications manager, TRACTO-TECHNIK GmbH & Co KG, Lennestadt, GermanyTel. +49(0)7025/843704E-mail: [email protected]

Authors:

Dott. Ing. Giacomo Bandera

Technical Manager, GHIZZONI S.p.A., Vidalenzo di Polesine (PR), Italy

Tel. E-mail:

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Fig. 1:

The Prime Drilling 50 t rig inside a factory plant in working position

Fig. 2:

The Orco River close to the under-river crossing site

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Fig. 3:

Typical winter conditions in the Alpine foreland. The 460 t-rig is working un-der all conditions

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Fig. 4:

The 460 t-PD-rig working for a 48" pipeline project in Calabria, Southern It-aly

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Fig. 5:

Reamers for the last two upsizing steps

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Fig. 6:

Pulling-in process of the 48" pipe

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Fig. 7:

Overview to the runway under-crossing for a water pipeline at Friedrichshafen

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Fig. 8:

The 100 t-Prime Drilling-unit of Bohlen & Doyen Company in working position in the Swiss Jura of Basel-Land

hdd applications in pipeline projects in europe · pdf filetrenchless technology 1 3r...

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