Methods Overview
Installation Methods in Pipeline Construction
Whether rehabilitating existing pipelines or installing entirely new routes – the choice of the appropriate installation method is crucial for safety, service life, and economic efficiency.
Our modern polyethylene (PE) pipe systems enable both classic open trench construction and innovative trenchless methods. We would be happy to advise you in detail and jointly select the most suitable method for your project!
Our modern polyethylene (PE) pipe systems enable both classic open trench construction and innovative trenchless methods. We would be happy to advise you in detail and jointly select the most suitable method for your project!
Installation Methods for Pipe Rehabilitation
Many existing pipeline networks are reaching their limits due to age. Rehabilitation offers an economical and technically convincing alternative to new construction. The focus here is primarily on trenchless installation methods with minimal intervention in infrastructure and the environment.
Whether relining, burstlining, or close-fit methods, our pipes are ideally suited for trenchless methods due to their special material properties. After rehabilitation, the integrity of the pipes can be reliably inspected and documented – a clear advantage for quality assurance and operational safety.
Source: Sustainability
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Relining
Relining is suitable for the rehabilitation of defective pipelines. Depending on the condition of the old pipe, scratches and notches may occur in the new pipe. V-seam welded steel pipes, in particular, pose a high risk.
Advantages of the Relining Method:
Economical solution for longer distances, especially with limited accessibility
Minimal disruption to the surface and environment, as few open excavations are required
The old pipe remains in the ground, significantly reducing construction time and excavation work
Additional protection from the surrounding old pipe
Also possible with media change, e.g., from wastewater to cable protection pipe
Relining is one of the trenchless renovation methods. The functionality of existing pipelines is restored by fully or partially incorporating the original substance and utilizing 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 pipe length is pre-stretched outside the insertion pit, while in long pipe relining, the pipe sections are connected 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 its sealing function. Relining involves a reduction in cross-section, which is often desired for capacity adjustment, e.g., due to the relocation of industry, commerce, and population. The new plastic pipes have comparatively low flow resistance values. As practice shows, despite the cross-sectional reduction, they often lead to an increase in throughput compared to the old pipes in need of rehabilitation.
The annular space between the old and PE pipelines is grouted after completion of construction. Guides and spacers fix and secure the pipeline in the desired position. Ballasting with water provides support. When grouting, the buckling resistance of the pipeline must be observed to prevent cross-sectional deformation. Grouting prevents a drainage effect from inflowing groundwater.
Old pipelines very often contain fittings, welding residues, and rough weld seam surfaces, which can lead to surface damage when the new pipe is pulled in. Therefore, egeplast offers protective jacket pipes in various designs.
Advantages of the Close-Fit Lining Method:
Trenchless rehabilitation with minimal surface intervention
No remaining annular space between old and new pipelines
Low cross-sectional reduction, as the liner fits snugly
Suitable for various media: drinking water, wastewater, and gas
High chemical resistance and long service life
Before renewal, the pipeline is disconnected. After a TV inspection, deposits and obstacles are carefully removed. If necessary, a temporary supply is installed for consumers during the construction period. Then, the close-fit liner is pulled into the pipeline to be rehabilitated using motor winches. Subsequently, the liner is heated with hot steam, activating the “memory effect.” By supplying steam and pressure, the close-fit pipe expands into its original round shape and, as it unfolds, fits precisely against the wall of the old pipe. Securely connected by electrofusion socket welding, the rehabilitated pressure pipe or gravity pipeline is re-integrated into the existing network.
After successful pressure testing and pipeline flushing, the new pipeline is ready for operation.
Burstlining
The energy for bursting the pipes is introduced by impact using modified pipe bursting tools or rams. The bursting and expanding body is guided stably in the pipe by means of a rope and winch. Dynamic methods are particularly suitable for use in compacted or stony soils and for brittle old pipes made of cast iron, stoneware, or concrete.
Advantages of the Burstlining Method:
Economical solution for longer distances, especially with limited accessibility
Minimal disruption to the surface and environment, as few open excavations are required
The old pipe remains in the ground, significantly reducing construction time and excavation work
Additional protection from the surrounding old pipe
Also possible with media change, e.g., from wastewater to cable protection pipe
The hydraulically generated bursting force is transmitted to the bursting and expanding body via a rod. Static burstlining is used for bursting old pipes made of brittle and ductile materials; the latter are cut with a special roller knife in the pipe invert. Subsequent expansion displaces the old pipe and calibrates the bursting channel for the pulling-in process.
The new pipe is subjected to significant stress during the bursting and pulling-in process. Fragments of the old pipe cause scratches and grooves, and stones cause point loads in the final position.
For this reason, the DVGW Code of Practice GW 323 recommends the use of protective jacket pipes. Furthermore, the requirements regarding minimum damage depth or compliance with permissible tensile stresses apply here as well, as with other trenchless installation methods.
In burstlining, a bursting and expanding body is pulled through the old pipe, displacing the pipe fragments into the soil, and simultaneously pulling in an industrially prefabricated pipe of the same or larger diameter. The surrounding soil must be displaceable, and the location and condition of parallel pipelines must be known. There are dynamically and statically operating systems that can break 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. Fragments and stones cause point loads during operation. Therefore, egeplast offers protective jacket pipes in various designs.
Dynamic Burstlining
Static Burstlining
Installation Methods for New Installations
From open trench construction to innovative techniques such as plowing, milling, or horizontal directional drilling, various methods are available for new pipeline sections.
Matching your project goals and local conditions, we will find the right method for your project. With our modern PE pipe systems, you benefit from high flexibility during installation and long service lives of over 100 years.
Open Trench Installation with Sand Bedding
When installing using the open trench method with sand bedding, the pipeline zone is precisely defined, and the pipe is laid in a protective sand bed. Afterwards, the surfaces must be restored.
Advantages of open trench installation with sand bedding:
Proven standard method with highest operational safety
Optimal protection against scratches and point loads
Easy quality control during installation
Suitable for all pipe materials and media
Regarding trench excavation, DIN 4124 “Excavations and Trenches” applies, which precisely defines how working space widths and shoring are to be carried out. The pipe must be free of grooves 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 Guideline W 400-2 prescribe embedding the pipe in sand or fine gravel.
Open Trench Installation without Sand Bedding
When installing using the open trench method without sand bedding, the pipe is laid directly in the pipe trench. Afterwards, the surfaces must be restored.
Advantages of open trench installation without sand bedding:
Cost-saving, as sand bedding can be omitted
Use of existing excavated soil possible (provided compactable material)
Shorter construction time and less logistics
More environmentally friendly due to less material usage
Source: Sustainability
Increasing cost pressure forces many utilities to question whether elaborate sand bedding for the new pipeline is necessary. If the excavated soil 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 occurring here.
Omitting sand bedding can lead to stones stressing the outer wall of the pipe in a point or linear manner over a longer period – in addition to operational loads such as internal pressure, soil, or traffic loads. If protection by a sand bed is omitted, 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 jacket pipes in various designs.
Plowing Method
With this method, the new pipe is continuously plowed in, and the pipe trench is immediately closed afterwards.
A prerequisite for such installation conditions is a pipe system that can withstand the increased loads occurring here.
Depending on soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permissible). In addition, stones can stress the outer wall of the pipe in a point or linear manner over a longer period – in addition to operational loads such as internal pressure, soil, or traffic loads.
A prerequisite for such installation conditions is a pipe system that can withstand the increased loads occurring here.
Depending on soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permissible). In addition, stones can stress the outer wall of the pipe in a point or linear manner over a longer period – in addition to operational loads such as internal pressure, soil, 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 impact 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 minimal damage to the terrain. The method can be used up to soil class 5 in undeveloped areas. Depending on the soil class, installation depths of up to 2 meters can be achieved.
Installation using the plowing method, with up to 5,000 meters of pipeline laid per working day, is probably the most economical form of new pipeline installation. The installation unit consists of the laying plow with plowshare and laying box and a cable winch installed on a truck or tracked vehicle. The laying unit is pulled by the cable winch towards this vehicle. When the plow reaches the vehicle, the cable winch is moved to the next section point, and the process repeats. In the starting pit, the plowshare is lowered to the desired laying depth. Depending on the pipe diameter, installation is possible up to OD 225 mm, and several pipelines can be plowed in simultaneously. In the trailing laying box, the pipelines are guided into the ground from above. The soil closes again behind the plowshare due to its own weight, but the process can be accelerated by machine use. Point loads, caused by, for example, stones in the ground, can cause damage to the pipeline. To achieve the targeted minimum service life in reality, pipelines made of 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 plowing method. The process sequence is identical; only the insertion of the pipeline takes place in the longitudinal direction. This means that the pipe string is pulled along with the plowshare over the entire laying length. Due to the significantly higher mechanical loads, the pipelines must have additional external pipe protection. It must 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.
Source: Sustainability
Milling Method
Special equipment mills a narrow pipe trench, into which the flexible pipe is inserted in the same work step. The excavated soil is used as backfill material.
Depending on soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permissible). In addition, stones can stress the outer wall of the pipe in a point or linear manner over a longer period – in addition to operational loads such as internal pressure, soil, or traffic loads – and thus cause damage.
Depending on soil conditions, the newly laid pipeline may be superficially scratched (max. 10% of the wall thickness is permissible). In addition, stones can stress the outer wall of the pipe in a point or linear manner over a longer period – in addition to operational loads such as internal pressure, soil, or traffic loads – and thus cause damage.
Advantages of the Milling Method:
Narrow trench for less surface disruption
Usable up to soil class 7 (even in difficult soils)
Excavated soil can be used as backfill material
Combinable with long pipe lengths for rapid installation
A motor-driven milling machine opens a narrow trench up to 60 cm wide and up to 2.5 m deep. The pipe is inserted into this trench, and the pipe trench is backfilled almost simultaneously, usually with the excavated material. Unlike the plowing method, this method can also be used for difficult soils up to soil class 7. The installation performance largely depends on the prevailing soil class but is lower than with the plowing method. Since this method generally does not involve laying the pipeline in a sand bed according to the rules of technology, pipelines made of a material with proven high stress crack resistance should be used.
Soil Displacement (Pipe Ramming)
Using a pipe rammer, house connection lines are generally "shot" through the ground over a few meters. The existing soil can scratch the new pipe to an impermissible depth. A maximum scratch depth of 10% of the pipe wall is permissible. Furthermore, surrounding stones cause point loads.
Advantages of the Milling Method:
Trenchless short-distance installation, ideal for house connections
Very low surface disruption
Fast construction progress, minimal traffic restrictions
Cost-effective for short lengths
The soil displacement method with a pipe rammer is mostly used for house connections. A pneumatically operated hammer drives a cavity into which the new pipeline is bedded. For this, the soil must be sufficiently displaceable. In loose and soft soils, static support for the pipe rammer is necessary, as insufficient friction with the soil is built up for independent propulsion. The design of the drive channel is therefore more precise in stony soils due to the lateral displacement of the stones. The lateral breakout of the pipe rammer occurs to a small extent. The target is sighted in the starting pit. With this method, pipelines up to OD 200 mm can be installed.
Horizontal Directional Drilling
Horizontal directional drilling (HDD) is a steerable wet drilling method. Depending on the nature of the soil and the 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
Possibility of cross-sectional 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 new pipeline
Horizontal directional drilling is used, for example, for longitudinal installations, undercrossings, and building underpasses, for drainage and irrigation tasks, for cable laying in traffic control technology, and for slope and embankment stabilization measures. The drilling is controlled by rotating the angled pilot drill head in the borehole.
The drilling fluid flows at high pressure from the drill head, loosens the soil and stones, and transports the drill cuttings out of the borehole. The drilling fluid is adapted to the respective subsoil and can contain, in addition to bentonite, a clay mineral, other additives that, for example, have an additional supporting effect on the borehole.
Depending on the desired pipe diameter, several reaming operations may be necessary after the pilot drilling to prepare the borehole for flushing in the media-carrying pipeline. An impact mechanism, which can be switched on in stony soils up to soil class 5, sometimes even soil class 6, not only facilitates propulsion 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 methods for gas and water pipelines – Requirements, quality assurance and testing,” pipelines for renewal in drinking water networks must at least comply with pressure class 10 bar. During the pulling-in process, the pipes must not be subjected to tensile forces exceeding the permissible limits. According to DVGW Worksheet GW 321 or at the request of the client, the tensile forces acting directly on the media pipe must therefore 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 pipelines of the SDR 11 series should be used.
The service life of the newly laid pipeline depends on the degree of integrity. Damage of up to 10% of the pipe wall thickness is tolerated by the material; scratches and grooves beyond that reduce the service life of the supply line. For this reason, the DVGW Code of Practice GW 321 also recommends the use of protective jacket pipes.