Overview of methods
Installation methods in pipeline construction
Whether it's the renovation of existing pipelines or the new installation of entire routes – the choice of the right installation method determines safety, service life and economy.
Our modern pipe systems made of polyethylene (PE) enable both classic open construction methods and innovative trenchless methods. We would be happy to advise you in detail and together select the method that is suitable for your project!
Our modern pipe systems made of polyethylene (PE) enable both classic open construction methods and innovative trenchless methods. We would be happy to advise you in detail and together select the method that is suitable for your project!
Installation methods for pipe renovation
Many existing pipeline networks are reaching their limits due to age. Renovation offers an economical and technically convincing alternative to new construction. The focus here is primarily on closed installation methods with minimal interventions in infrastructure and the environment.
Whether it’s relining, burstlining or close-fit methods, our pipes are ideally suited for closed methods due to their special material properties. After the renovation, the integrity of the pipes can be reliably tested and documented – a clear advantage for quality assurance and operational safety.
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Relining
Relining is suitable for the renovation of defective pipelines. Depending on the condition of the old pipe, scratches and notches may occur in the new pipe. In particular, V-seam welded steel pipes pose a high risk.
Advantages of the relining method:
Economical solution for longer distances, especially with poor accessibility
Low impact on the surface and environment, as hardly any open construction pits are required
The old pipe remains in the ground, which significantly reduces construction time and earthworks
Additional protection through the surrounding old pipe
Also possible with media change, e.g. from waste water to cable protection pipe
Relining is one of the trenchless renovation methods. The functionality of the existing pipelines is restored with full or partial inclusion of the original substance and using the existing pipeline route. Industrially prefabricated and tested plastic pipes are used, which are pulled or pushed into the old pipe with or without an annular space. In pipe string relining, the entire length of the section is pre-stretched outside the insertion pit; in long pipe relining, the pipe sections are connected to each other in the insertion pit during insertion.
Depending on the condition of the old pipe, the new pipe must also perform static tasks in addition to the sealing function. Relining is accompanied by a cross-sectional reduction, which is often desired for reasons of capacity adjustment, e.g. due to the relocation of industry, commerce and population. The new plastic pipes have comparatively low resistance values in terms of flow technology. As practice shows, they often cause an increase in throughput compared to the old pipes in need of renovation, despite the reduction in cross-section.
The annular space between the old and PE pipeline is backfilled after completion of the construction work. Guides and spacers fix and secure the pipeline in the desired position. Ballasting with water has a supporting effect. When backfilling, the buckling pressure resistance of the pipeline must be observed in order to prevent cross-sectional deformation. A drainage effect caused by inflowing groundwater is prevented by backfilling.
Old pipelines often contain fittings, welding residue, and rough weld seam surfaces, which can lead to surface damage when pulling in the new pipe. Therefore, egeplast offers protective casing pipes in various versions.
Close-Fit Lining
With Close-Fit-Lining with PE pipes, pipelines are renewed efficiently, permanently and in an environmentally friendly manner with a factory-made PE pipe. For this purpose, the new pipe is specially thermo-mechanically deformed or folded during production. The max. reeled pipe length is determined by the pipe diameter. Depending on the nominal width, several hundred meters can be installed in one operation due to the reduced cross-section of the new pipe. With the supply of steam and pressure, the new pipe returns to its original round shape and adapts to the old pipe as a statically independent pipe.
Advantages of the Close-Fit-Lining method:
Trenchless renovation with minimal impact on the surface
No remaining annular space between old and new pipe
Low cross-sectional reduction, as the liner fits tightly
Suitable for various media: drinking water, waste water and gas
High chemical resistance and long service life
In the run-up to the renewal, the pipeline is separated. After a TV inspection, deposits and obstacles are carefully removed. If necessary, a temporary solution is installed to supply consumers during the construction period. Then the close-fit liner is pulled into the pipe to be renovated using motor cable winches. The liner is then heated with superheated steam. The “memory effect” is activated. By supplying steam and pressure, the close-fit pipe expands into its actually round shape and nestles precisely against the wall of the old pipe when it unfolds. Securely connected by heating coil sleeve welding, the renovated pressure pipe or gravity pipe is re-integrated into the existing network.
After a successful pressure test and pipe flushing, the new pipe is ready for operation.
Pipe Bursting
The energy input for bursting the pipes is carried out by modified soil rockets or rams. The bursting and expansion body is guided in a stabilizing manner in the pipe by means of a cable and winch. Dynamic methods are particularly suitable for use in compacted or stony soils and for brittle old pipes made of gray cast iron, stoneware or concrete.
Advantages of the burstlining method:
Economical solution for longer distances, especially with poor accessibility
Low impact on the surface and environment, as hardly any open construction pits are required
The old pipe remains in the ground, which significantly reduces construction time and earthworks
Additional protection through the surrounding old pipe
Also possible with media change, e.g. from waste water to cable protection pipe
The hydraulically generated bursting force is transmitted to the bursting and expansion body via a linkage. Static burstlining is used to burst old pipes made of brittle and ductile materials; the latter are cut with a special roller knife in the pipe base. A subsequent expansion displaces the old pipe and calibrates the burst channel for the pulling-in process.
The new pipe is subjected to heavy stress during the bursting and pulling-in process. Old pipe shards cause scratches and scores, stones cause point loads in the final position.
For this reason, the use of protective jacket pipes is recommended in the DVGW code of practice GW 323. In addition, the requirements regarding the minimum thickness of damage or compliance with the permissible tensile stresses apply here, as with the other trenchless installation methods.
During burstlining, a bursting and expansion body is pulled through the old pipe, the pipe shards are displaced into the ground and at the same time an industrially prefabricated pipe with the same or a larger diameter is pulled in. The surrounding soil must be displaceable, the location and condition of parallel pipes must be known. There are dynamically and statically working systems that can break up almost all pipe materials, including reinforced concrete pipes.
Depending on the material and condition of the old pipe, scratches and notches may occur in the new pipe. Shards and stones cause point loads during operation. Therefore, egeplast offers protective casing pipes in various versions.
Dynamic burstlining
Static burstlining
Installation methods for a new installation
From open construction to innovative techniques such as plowing, milling or horizontal directional drilling, various methods are available for new pipe sections.
We identify the most suitable method for your project, aligning with your specific goals and local conditions. With our modern PE pipe systems, you benefit from high flexibility during Installation and service lives exceeding 100 years.
Open Trench Installation with sand bedding
For Open Trench Installation with sand bedding, the pipeline zone is precisely defined, and the pipe is laid in a protective sand bed. Subsequently, the surfaces must be restored.
Advantages of Open Trench Installation with sand bedding:
Proven standard method with maximum operational safety
Optimal protection against scratches and point loads
Easy quality control during installation
Suitable for all pipe materials and media
With regard to the pipe trench design, DIN 4124 “Excavations and trenches” applies, which precisely defines how working space widths and shoring are to be managed. The pipe must be free of scores and scratches, then the soil surrounding the pipe is prepared in such a way that the pressure-bearing medium pipe is protected from external influences. DIN EN 805 and DVGW Directive W 400-2 prescribe embedding the pipe in sand or fine gravel.
Open Trench Installation without sand bedding
For Open Trench Installation without sand bedding, the pipe is laid directly in the pipe trench. Subsequently, the surfaces must be restored.
Advantages of Open Trench Installation without sand bedding:
Cost-saving, as sand bedding can be dispensed with
Use of existing soil excavation possible (provided compactable material)
Shorter construction time and lower logistics
More environmentally friendly due to less material usage
Increasing cost pressure is forcing many suppliers to question whether elaborate sand bedding of the new pipe is necessary. If the soil excavation is compactable, it can be reused for backfilling – instead of sand. A prerequisite for such installation conditions is a pipe system that can withstand the increased loads that occur here.
Omitting sand bedding can lead to stones exerting point or linear loads on the outer wall of the pipe over a longer period – in addition to operational loads such as internal pressure, soil, or traffic loads. If protection by a sand bed is foregone, the selected pipe system must be able to withstand typical surface damage from scratches and especially point loads, so that these do not lead to stress cracks. Therefore, egeplast offers protective casing pipes in various versions.
Plowing Method
In this method, the new pipe is continuously plowed in and the pipe cut is then immediately closed again.
A prerequisite for such installation conditions is a pipe system that can withstand the increased loads that occur here.
Depending on the soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permitted). In addition, stones can load the outer wall of the pipe in a point or line shape over a longer period of time – in addition to the operating loads such as internal pressure, earth or traffic loads.
A prerequisite for such installation conditions is a pipe system that can withstand the increased loads that occur here.
Depending on the soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permitted). In addition, stones can load the outer wall of the pipe in a point or line shape over a longer period of time – in addition to the operating loads such as internal pressure, earth or traffic loads.
Advantages of the plowing method:
Very high installation performance (up to approx. 5 km per day)
Minimal soil intervention and rapid restoration
No groundwater lowering required
Particularly economical for long routes in undeveloped areas
The influence of the plow on the soil is relatively low. Groundwater lowering is not necessary with this installation method. Therefore, this installation method is very environmentally friendly, also due to the low level of damage to property. The method can be used up to soil class 5 in undeveloped areas. Depending on the soil class, laying depths of up to 2 meters can be achieved.
Installation using the ploughing method, with up to 5,000 meters of pipeline installed per working day, is arguably the most economical form of new pipeline Installation. The Installation unit consists of the ploughing machine with a plough blade and Installation box, and a winch installed on a truck or tracked vehicle. The Installation unit is pulled by the winch towards this vehicle. Once the plough reaches the vehicle, the winch is repositioned at the next section point, and the process repeats. In the starting pit, the plough blade is lowered to the desired Installation depth. Depending on the pipe diameter, up to OD 225 mm can be installed, and multiple pipelines can be ploughed in simultaneously. In the trailing Installation box, the pipelines are guided into the ground from above. The soil closes again behind the plough blade due to its own weight, but the process can be accelerated by machine use. Point loads, caused by, for example, stones in the soil, can cause damage to the pipeline. To achieve the desired minimum service life in practice, pipelines made from a material with proven high stress crack resistance should be used.
A variant of the plowing method, especially for pipe materials whose permissible bending radii are too large for the normal plow, is the rocket plow method. The procedure is identical, only the pipe is inserted in the longitudinal direction. This means that the pipe string is pulled together with the plug share over the entire laying length. Due to the significantly higher mechanical loads, the pipelines must have additional external pipe protection. It should be noted that the permissible tensile forces of the pipeline and the connection are not exceeded. The length of the pipe string is limited by the tensile forces.
Milling process
Special equipment mills a narrow pipe trench, into which the flexible pipe is inserted in the same operation. The excavated soil is used as backfill material.
Depending on the soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permitted). In addition, stones can load the outer wall of the pipe in a point or line shape over a longer period of time – in addition to the operating loads such as internal pressure, earth or traffic loads – and thus cause damage.
Depending on the soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permitted). In addition, stones can load the outer wall of the pipe in a point or line shape over a longer period of time – in addition to the operating loads such as internal pressure, earth or traffic loads – and thus cause damage.
Advantages of the milling method:
Narrow trench for less surface disruption
Can be used up to soil class 7 (even in difficult soils)
Excavated soil can be used as backfill material
Can be combined with long pipe lengths for rapid Installation
A motor-driven trencher opens a narrow trench up to 60 cm wide and up to 2.5 m deep. The pipe is laid in this trench, and the trench is backfilled almost simultaneously, usually with the excavated material. Unlike the ploughing method, this procedure can also handle difficult soils up to soil class 7. The Installation performance largely depends on the prevailing soil class but is lower than with the ploughing method. Since this method typically does not involve the Installation of the pipeline in a sand bed according to technical standards, pipelines made from a material with proven high stress crack resistance should be used.
Soil displacement (soil displacement hammer)
By means of a soil displacement hammer, house connection lines are generally "shot" through the soil over a few meters. The existing soil can scratch the new pipe impermissibly deeply. A maximum scratch depth of 10% of the pipe wall is permitted. Furthermore, surrounding stones cause point loads.
Advantages of the milling method:
Trenchless short-distance installation, ideal for house connections
Very low surface impact
Fast construction progress, hardly any traffic restrictions
Cost-effective for short lengths
The soil displacement installation method using a pipe ramming system is primarily employed for house connections. A pneumatically operated hammer creates a cavity in which the new pipeline is laid. For this, the soil must be sufficiently displaceable. In loose and soft soils, static support for the pipe ramming system is necessary, as insufficient friction with the soil is generated for self-propelled advancement. The formation of the bore channel is therefore more precise in stony soils due to the lateral displacement of stones. Lateral deviation of the pipe ramming system is minimal. The target is sighted from the launch pit. This method allows for the installation of pipelines up to OD 200 mm.
Horizontal Directional Drilling (HDD)
Horizontal directional drilling (HDD) is a steerable wet drilling method. Depending on the soil conditions and drilling radius, scratches, notches, and point loads from stones can endanger the newly installed pipe.
Advantages of Horizontal Directional Drilling:
Trenchless rehabilitation with minimal surface intervention
Option for cross-section enlargement by up to three nominal diameters
High economic efficiency due to reduced construction time and lower civil engineering effort
Suitable for various media: drinking water, wastewater, and gas
Statically self-supporting and as-new pipeline
Horizontal directional drilling is used, for example, in longitudinal installations, siphons and building undercrossings, for drainage and irrigation tasks, for cable laying in traffic control technology, and for slope and dam stabilization measures. The drilling is controlled by rotating the angled pilot drill head in the borehole.
The drilling fluid flows under high pressure from the drill head, loosening the soil and stones and conveying the cuttings out of the borehole. The drilling fluid is adapted to the respective ground conditions and can contain, in addition to bentonite, a clay mineral, further additives that, for example, provide additional support to the bore channel.
Depending on the desired pipe diameter, several reaming passes are necessary after the pilot bore to prepare the bore channel for the installation of the media-carrying pipeline. An impact mechanism, which can be engaged in stony soils up to soil class 5, and in some cases soil class 6, not only facilitates advancement but also the steering process. For drilling in rock, a downhole motor with roller bits is used upstream.
According to DVGW Worksheet GW 321 “Steerable Horizontal Directional Drilling for Gas and Water Pipelines – Requirements, Quality Assurance and Testing”, pipelines for rehabilitation in drinking water networks must correspond to at least pressure class 10 bar. During the pulling-in process, the pipes must not be subjected to forces exceeding the permissible tensile loads. Therefore, in accordance with DVGW Worksheet GW 321 or at the client’s request, the tensile forces acting directly on the media pipe must be measured and recorded. The measurement is carried out with a tensile force measuring device mounted in front of the pipe to be pulled in. Due to the mechanical stresses arising from this installation method, especially for small pipe diameters, only SDR 11 series pipelines should be used.
The service life of the newly installed pipeline depends on its degree of integrity. Damage of up to 10% of the pipe wall thickness is tolerated by the material; scratches and grooves exceeding this reduce the service life of the supply line. For this reason, the use of protective casing pipes is also recommended in the DVGW standard GW 321.