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Relining of pipe systems: conditions, benefits and application through case-study

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Relining is one of the best alternatives available today for pipe system rehabilitation. This trenchless solution is particularly interesting for urban agglomerations, as a smaller diameter pipe is pushed or pulled through the old pipeline. Relining creates a leak-tight "pipe within a pipe" system, which is as good as new in both structural and hydraulic terms. Relining can be performed with both circular and special, non-circular (NC) profiles. The latter is especially advantageous for the rehabilitation of old sewers, many of which were constructed in a variety of ovoid-like shapes. This paper presents the typical steps that are performed for pipeline rehabilitation with non-circular profiles, as well as an applied case study (a project implemented in the city of Würzburg in Germany).
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Ovidius University Annals Series: Civil Engineering, Issue 19, 2017
___________________________________
Manuscript received 14.06.2017
Victor Vladimirov is with the Doctoral School, Technical University of Civil Engineering Bucharest, Lacul
Tei Bvd., no. 122 124, Romania (corresponding author phone: +43-463-48- 2424; fax: +43-463-48-2121;
e-mail: victor.vladimirov@hobas.com).
Thomas Simoner is with HOBAS Pipes International, Pischeldorfer Straße 128, 902, Klagenfurt, Austria
(e-mail: thomas.simoner@hobas.com).
Ioan Bica is with Technical University of Civil Engineering Bucharest, Lacul Tei Bvd., no. 122 124,
Romania (e-mail: bica@utcb.ro).
ISSN-1584-5990 ©2000 Ovidius University Press
Relining of pipe systems: conditions, benefits and
application through case-study
Victor Vladimirov, Thomas Simoner and Ioan Bica
_____________________________________________________________________
Abstract Relining is one of the best alternatives available today for pipe
system rehabilitation. This trenchless solution is particularly interesting for
urban agglomerations, as a smaller diameter pipe is pushed or pulled through
the old pipeline. Relining creates a leak-tight “pipe within a pipe” system, which
is as good as new in both structural and hydraulic terms. Relining can be
performed with both circular and special, non-circular (NC) profiles. The latter
is especially advantageous for the rehabilitation of old sewers, many of which
were constructed in a variety of ovoid-like shapes. This paper presents the
typical steps that are performed for pipeline rehabilitation with non-circular
profiles, as well as an applied case study (a project implemented in the city of
Würzburg in Germany).
Keywords pipeline rehabilitation, urban areas, relining, trenchless, non-
circular
_____________________________________________________________________
1. INTRODUCTION
Much of the water pipe infrastructure in European cities is outdated and requires
frequent maintenance and repair. European market potential for pipe rehabilitation
was estimated at 2,5 - 3,5 billion per year, equivalent to about 20.000 km of pipe
that will need intervention in the next years [1]. In the USA, the needed funding is
estimated at up to 325 billion $ for the next 20 years [2].
Digging up and replacing old underground pipeline systems is one of the most
expensive choices and may cause significant disruptions to the landscape, with
Ovidius University Annals Series: Civil Engineering, Issue 16, October 2014
aggravating conditions in larger urban areas. The total cost for water pipes
rehabilitation includes both direct costs and social costs (which are difficult to
quantify) resulting from traffic delays, public inconvenience and effects on the
environment [3]. A cost-effective solution to this problem is pipe rehabilitation or
replacement with trenchless solutions. Some of the most relevant aspects to consider
include state of the existing pipeline, static load capacity, variable pipe lengths,
custom cross-section shapes, various jointing systems, hydraulic capacity, corrosion
resistance, abrasion resistance, installation challenges (easy handling, without
significant traffic or landscape disruptions, installation irrespective of weather
conditions) as well as ensuring a long service life after intervention.
Trenchless methods include: relining” (a smaller diameter pipe is pushed or
pulled through the old pipeline), “close-fit lining” (the liner pipe is mechanically
deformed or folded and after insertion is returned to the original form by application
of heat or pressure), “spray-on” (lining applied to a cleaned and dried host pipe wall),
“pipe bursting” (a larger diameter pipe than the old pipeline is installed with the help
of a hydraulic pipe cracker which gradually brakes the old pipe open), “cured liner”
(insertion of impregnated liner and cured with water or steam) or “cement mortar
lining” (cement lining applied to a cleaned and dried host pipe wall) [4].
2. THE RELINING METHOD
Relining (slip lining) has been used since the mid twentieth century and is one
of the most cost effective trenchless renewal systems [5]. A smaller diameter pipe is
pushed or pulled through the old pipeline. Relining creates a leak-tight “pipe within a
pipe” system, which is as good as new in both structural and hydraulic terms. The loss
in flow area may be compensated by lower friction loss. Thus, although slip lining
decreases the total cross sectional area of a culvert, using a smoother pipe material
with a smaller Manning’s Roughness coefficient may compensate this issue [6].
The method presents considerable advantages: the old pipeline is rehabilitated
quickly and easily and the client benefits from a pipeline that is of the same quality as
a new one. In addition, the remaining annular space between the host and liner pipes
is usually filled with pressure-resistant grouting consisting of a mixture of binding
materials. This fixes the inserted pipe in position and can take over the structural load
capacity. See Figure 1 for a sectional diagram depicting the old host pipe as well as
the new liner pipe and the annular space.
In addition, slip lining does not require excavation except at selected locations
and therefore it offers many benefits compared with replacement or repair using the
open-cut method (less traffic disruption, less disturbance to the environment, and less
disruption for the public) [7]. For example, in the case study presented in this paper
there was only one entry pit for the rehabilitation of a 875-meter section. Even if the
installation site provided limited storage conditions due to its location within the city,
with efficient organization measures the rehabilitation works initially scheduled for
nine months were completed within three months.
Ovidius University Annals Series: Civil Engineering, Issue 16, October 2014
Fig. 1: Section with host pipe and new liner pipe [7]
Typical materials used in water distribution systems are steel, concrete, ductile
iron, polyvinyl chloride (PVC), polyethylene (PE), high density polyethylene (HDPE)
and glass reinforced plastic (GRP). GRP relining pipes are particularly suitable for
pipe rehabilitation, as they are light in weight, corrosion resistant, easy to install and
resist the load from the grouting. GRP is manufactured as a composite of wound glass
fibers, resin, filler, and sand applied in either a centrifugal process or a winding type
process. Relining can be performed with both circular and special, non-circular (NC)
profiles. A typical non-circular glass reinforced plastic (GRP) profile is depicted in
Figure 2.
Fig. 2: Non-circular section with host pipe and new liner pipe [8]
Non-circular systems are particularly suitable for rehabilitation of corroded
sewer lines. The pipes can be designed for specific loads and project requirements,
while also taking structural dimensions, technical specifications and regulations
regarding chemical resistance into account.
Ovidius University Annals Series: Civil Engineering, Issue 16, October 2014
In addition to classic cross sections, such as circular, egg, jaw, or kite-shaped
pipes, further combinations of shapes may be prepared to fit the condition of the old
sewer. A suitable jointing technology is then selected: where shapes are completely
convex, pipes are usually joined with push-on couplings, while for combinations of
convex and concave or even shapes glued or laminated joints are typical. Suitable
shafts and tangential manholes may be also considered to obtain a complete system
including pipes with special cross-sections, lateral connections and manholes. This
offers a lot of flexibility in terms of pipe system rehabilitation.
The typical steps to evaluating and implementing a rehabilitation project with
non-circular profiles are: (i) assessment and static examination of the old sewer, (ii)
cleaning of the old pipeline, (iii) calibration activities, (iv) installation, (v) lamination
for connections to adjacent pipes and shafts, (vi) insulation of the ring area and (vii)
pressure test of the pipeline.
Reference standards and technical rules include the newly published standard
ISO 16611 for non-circular GRP pipes and joints, EN 752 “Drain and sewer systems
outside buildings (Part V: Rehabilitation)”, EN 1610 “Construction and testing of
drains and sewers”. For example, EN 752 differentiates between “rehabilitation”
(complete process of reconstruction), “repair” (localized adjustment of damage),
“renovation” (improvement of functionality) and “renewal” (construction of new
pipelines that overtake the function of the previous ones). Pipelines should be tight,
efficient in terms of water flow, safe to operate and chemically resistant [9].
For relining the first step (i) is to perform a condition assessment and static
examination of the old sewer. As shown in Figure 3 below, three situations are
considered: (I) the old pipe system is still viable, (II) the old pipe system is still viable
with some defects (i.e. lengthwise fissures, small degree of pipe deformation with
functional side bedding) and finally (III) the old pipe system is no longer viable. In
cases where the necessity of a new profile is certain, the expected statics of the new
profile and determination of wall thickness can be performed by means of dedicated
computer programs (i.e. Finite Elements FEM calculations).
Fig. 3. Static examination of the old sewer [10]
Ovidius University Annals Series: Civil Engineering, Issue 16, October 2014
Once the calculations are complete, the second typical step (ii) is the cleaning of
the old pipeline, followed by the third (iii) calibration step.
Calibration can be performed manually or digitally. In case of manual
calibration, no digital image is needed and a calibration model can be constructed (see
Figure 4).
Fig. 4. Calibration models
The cross section of the model can be adjusted to a reasonable degree to match
the old sewer. In case of digital calibration, the acquisition and representation of
structures in three-dimensional space represents best practices and may bring
significant benefits. For example, with help of non-contact measurement technology,
old structures need to be entered only to a small extent, as compared with the manual
calibration method. In addition, an extremely high measuring point density provides
an excellent image of the geometry of the channel. With digital calibration, a 3-D
image of the old sewer is generated and cross sections across the old pipeline can be
defined as basis for the installation plan. Pipes can then be set-up in a defined
sequence, per the local conditions and installation plan.
The next typical step (iv) is the installation of the pipes. This includes further
activities such as production of the pipes per defined specifications, preparation of the
construction site (i.e. digging of installation pits if necessary), transport and set-up of
pipes within the old pipeline. Protocols of the pipe profiles, wall thickness
measurement, length, optical appearance are customarily filled-in before and after
installation. The profile of the pipe can be specifically adapted to the required local
conditions (see Figure 5).
The next steps are (v) lamination for connections with adjacent pipes and shafts,
followed by (vi) insulation of the annular area between the old and new pipelines.
Typical requirements for the insulation are a strength of 5 N/mm2, high fluidity, low-
shrinkage and sand-free. Insulation is processed layer by layer on subsequent sections.
Although grouting is not obligatory, performing this step may bring additional
benefits such as increased resistance to buckling when the pipe is dewatered,
increased resistance to shear failures at lateral connections, enhanced protection of the
liner pipe in the event of host pipe failure and longer service life of the liner due to
load sharing [11].
Ovidius University Annals Series: Civil Engineering, Issue 16, October 2014
Fig. 5. Example of pipe profiles for relining [8]
The final typical step is (vii) a pressure test of the system. Tests are usually
performed per EN 1610 “Construction and testing of drains and sewers” [12].
3. CASE STUDY: RELINING PROJECT IN WÜRZBURG, GERMANY
Wastewater in the town of Würzburg flows through a 540-km-long and over the
centuries extended sewer system. The collector main collector (1.9 km) was in some
areas more than 100 years old. In 2013 investigation of the status of the channel was
organized and a restoration plan was subsequently devised. A section of 875 meters
was identified in need of immediate rehabilitation [13]. The damage included
corrosion, leaks and infiltration, which was facilitated by the proximity of the River
Main. Many of the fittings for ventilation were cracked and there were deposits at the
bottom of the main sewer.
Re-lining with GRP pipes was considered the best solution for this section in
terms of sustainable rehabilitation and long service life after intervention. Building a
new channel did not represent an economic alternative due to the location, depth and
dimensions of the collector. The investment included rehabilitation with new profiles,
calibration measurements and alignment to the adjacent shafts as well as renovation
of connections to the larger water system.
The egg-shaped brick sewer had no standard dimensions, but a special cross-
section of 1400 x 2250 mm. Non-circular profiles 1260 x 2110 mm were used which
reduced the diameter of the liner pipe with approximately 16% than that of the old
pipe. Flow capacity is one of the major factors to be considered in the design of slip
line rehabilitation. The outside diameter of the liner pipe is usually at least 10%
smaller than the inside diameter of the host pipe [7]. However, even with 16%
reduction, the hydraulic requirements could still be fulfilled. This represented a
paramount condition, due to the proximity to the waste water treatment plant and to
the average rainfall of about 600 mm/year.
Prior to the start of the actual rehabilitation works, the old sewer profile was
digitized with a 3D laser scanner. The resulting three-dimensional image of the
channel served as basis for the installation plan. The scanning of the profiles was
Ovidius University Annals Series: Civil Engineering, Issue 16, October 2014
performed with up to 50 000 dots per second. At the same time, an integrated camera
assured a photographic depiction of the profiles. The length of the pipe segments was
determined by the local conditions. The maximum length was limited by the size of
the installation pit or by the curves of the channel. Short lengths were necessary in
curvature areas. In addition, the position of the connecting lines was considered in
relation to the profiles' lengths, so that no connection would come directly in the pipe
sleeve areas. These considerations were included in the installation plan and profiles
were assigned sequential numbers so that delivery and installation on site could be
performed „just-in-time". In addition, manual calibration of the structure was also
performed with a custom-built calibrating model to have a simulation of the entire
pipeline. The non-circular pipe wall was built up by means of filament winding.
A total of 401 non-circular profiles in lengths of 1 to 2.35 m and with a wall
thickness of 25 mm were used in the rehabilitation of the old sewer [13].
The installation works were conducted from one single pit, which is why 533 m
of pipe were installed in flow direction and another 342 m to the opposite direction. In
the areas of manholes and special structures, the GRP profiles were cut open per the
manhole dimensions to create accesses and emergency exits. Then, the pipes were
connected with push-to-fit couplings using a coupling device and secured against
buoyancy by means of spacers. The annular space of 3 cm was grouted. Connections
to pipes and shafts in the system were laminated. Nine months had been scheduled for
the implementation of this project. Thanks to the continuous coordination of all
parties involved, the installation was completed within 3 months, after no more than
one third of the designated construction time.
4. CONCLUSION
Water loss in distribution systems represents a relevant cost factor for
municipalities as well as a waste of a critical resource (especially in areas where water
is scarce). Much of the existing infrastructure in Europe requires frequent
maintenance and needs rehabilitation.
Digging up and replacing old underground pipeline systems is often an
expensive choice, with aggravating conditions in urban areas (i.e. disruptions to
traffic and to the landscape). Trenchless methods usually provide a more cost and
time effective solution. Among trenchless rehabilitation methods, relining with non-
circular pipe systems based on glass fiber reinforced plastics is particularly suitable
for outdated and corroded sewer lines and provides a high corrosion resistant pipeline
solution for many decades.
The study-case further indicates that identification of the rehabilitation solution
is based on multiple of factors: state of the existing infrastructure, location, specific
needs based on the structural integrity of the section requiring remedial action,
potential for contaminants to enter the pipe system as well as cost efficiency of the
rehabilitation and of the operation of the pipeline.
Ovidius University Annals Series: Civil Engineering, Issue 16, October 2014
5. REFERENCES
[1] S. Bianchi, Final Report Summary Novel Technology for Low Cost Re-lining of
Pipe Infrastructure, Italian Association for Trenchless Technology (IATT), CORDIS
European Commission's Portal, pp.1, 2014
[2] R. Morrison et.al, State of Technology for Rehabilitation of Water Distribution
Systems, Environmental Protection Agency (EPA), pp.3, 2013
[3] R.A. McKim, Bidding Strategies for Trenchless Technologies, Cost Engineering,
Vol. 40, pp. 37-41, 1998.
[4] J.C. Matthews, How to select the proper relining method for your work,
Trenchless Technology Pipe Relining Supplement, pp.14, 2013
[5] M. Najafi, Trenchless Technology: Planning, Equipment, and Methods, New
York: McGraw-Hill Companies, Inc., 2013
[6] M. Najafi, S. Salem, D. Bhattachar, B. Salman, and R. Patil, An Asset
Management Approach for Drainage Infrastructure and Culvert, Midwest Regional
University Transportation Center, College of Engineering, University of Wisconsin,
Madison, 2008
[7] J. Q. Zhao, Slipline Rehabilitation of Watermains with High-Density Polyethylene
Pipe, Construction Technology Updates Number 56, Institute for Research in
Construction, National Research Council of Canada, pp.1-3, 2013
[8] Product catalogue, NC Line. Non-Circular Profiles, HOBAS Pipes International
GmbH, 2014
[9] CEN European Committee for Standardization, EN 752 Drain and sewer systems
outside buildings (Part V: Rehabilitation), 1997
[10] DWA (German Association for Water, Wastewater and Waste), ATW DVWK M
127 Static calculations for the rehabilitation of sewers and drains with lining and
assembly process (Part 2), 2010
[11] J.Q. Zhao and L. Daigle, Structural Performance of Sliplined Watermain,
Canadian Journal of Civil Engineering, Vol. 28, No. 6, pp. 969-978, 2001.
[12] CEN European Committee for Standardization, EN 1610 Construction and
testing of drains and sewers, 2011
[13] Municipality report, Kanalbaumanagementbericht, Municipality of Würzburg,
pp. 33-35, pp. 42-48, 2014
ResearchGate has not been able to resolve any citations for this publication.
Technical Report
Full-text available
The impact that the lack of investment in water infrastructure will have on the performance of aging underground infrastructure over time is well documented and the needed funding estimates range as high as $325 billion over the next 20 years. With the current annual replacement rate averaging 0.5%, pipes would be expected to last for 200 years, but most pipes are designed for 50 or 100 year life cycles. While this replacement rate may be sufficient in the immediate term because pipes are still relatively young, as systems grow older, the necessary replacement rates will inevitably increase. In addition to the necessary funding, congestion above and below ground is making the replacement of water mains more difficult for utility owners as is the lack of public tolerance for the disruption caused by construction work. There is an increasing availability of technologies for rehabilitation of existing pipes, which provides solutions that minimize or alleviate these problems, while providing realistic and potentially cost-effective alternatives to traditional open cut replacement. The primary objectives of the report are: • To review current and emerging rehabilitation technologies for water distribution mains and services. • To understand the needs of water utilities for renewal of their infrastructure and to identify technology gaps that should be addressed in order to meet these needs. • To identify key performance parameters for various rehabilitation technologies and to gather and document this information for rehabilitation technologies that are available for use in the market. This report contains a comprehensive review and evaluation of existing and emerging renewal technologies for water distribution system mains and services. This report covers technologies used for the repair, rehabilitation, and replacement of water mains and service lines. The available technologies for water pipeline renewal leave “gaps” in terms of certain needs that are unmet that fall into two main categories: data gaps in terms of knowledge of the existing pipe condition; and capability gaps in terms of the available renewal technologies. Accurate data on pipe condition is necessary for the successful selection and design of renewal technologies. Data gaps relate to the amount and/or quality of direct physical inspection data on a pipe, which may be obtained either externally or internally. Obtaining external data requires costly excavation, while internal data can be obtained over the full internal surface area of the pipe, but this typically requires the main to be shutdown and dewatered. Capability gaps remain, despite the available rehabilitation technologies generally meeting renewal needs. Reopening service connections after lining still requires excavation with some technologies at each connection location and where service connections are frequent; this becomes as disruptive as a full-length excavation. Operational aspects such as access requirements and the length of time that the main is out of service are also areas where gaps exist between capability and customers’ needs. A gap also remains in the understanding of the long-term performance of various rehabilitation technologies and their materials. These materials and methods have been introduced recently and therefore their installed performance has not been studied over time. To overcome the gaps identified, it is recommended that innovative rehabilitation technologies be demonstrated in field conditions and measured against a clearly defined set of performance criteria. An additional research need is to identify accelerated aging test protocols that would help system owners to predict the long-term performance of the products and technologies used. It is also recommended that a retrospective analysis of water main rehabilitation materials be conducted to understand service life performance of field-installed materials. These data, along with the documented performance evaluation from a demonstration program, would be essential in providing utility decision makers with the information needed for selecting technologies and materials that meet their needs. iii
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Sliplining is a trenchless pipe rehabilitation technology that offers many advantages compared with traditional open-cut and cover methods. This Update presents information on sliplining installation, performance and cost, based on recent work at NRC's Institute for Research in Construction. Le tubage est une technologie de réhabilitation sans tranchée des conduites, qui offre de nombreux avantages par rapport à la méthode traditionnelle d'excavation. Ce numéro renferme des informations sur la réalisation, la performance et les coûts du tubage, tirées d'un projet récent mené par l'Institut de recherche en construction du CNRC. PRAC
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Rehabilitation of a watermain by grouted sliplining is usually carried out when the existing pipe is only partially deteriorated. Although designs that neglect the structural contributions from the existing pipe and the grout are generally conservative, the performance of the rehabilitated pipe needs to be better understood for effective design and management of buried water pipes. Presented in this paper is a practical method for the determination of load sharing and circumferential stresses in a sliplined pressure pipe. The laboratory tests show that the load carrying capacity of a cast iron pipe increases substantially after it is sliplined and grouted. Results also indicate that the eccentricity between the host pipe and the inserted pipe and the direction of eccentricity have an impact on the rupture load of the sliplined pipe. The effects of the host pipe wall thickness and the grout strength are also discussed. Although the method is based on a pressurized watermain, it can be used to assess the load carrying capacity of a non-pressurized pipe such as a sewer pipe. The use of this method is demonstrated through an example.
Final Report Summary Novel Technology for Low Cost Re-lining of Pipe Infrastructure, Italian Association for Trenchless Technology (IATT), CORDIS European Commission's Portal
  • S Bianchi
S. Bianchi, Final Report Summary Novel Technology for Low Cost Re-lining of Pipe Infrastructure, Italian Association for Trenchless Technology (IATT), CORDIS European Commission's Portal, pp.1, 2014
How to select the proper relining method for your work, Trenchless Technology -Pipe Relining Supplement
  • J C Matthews
J.C. Matthews, How to select the proper relining method for your work, Trenchless Technology -Pipe Relining Supplement, pp.14, 2013
Trenchless Technology: Planning, Equipment, and Methods
  • M Najafi
M. Najafi, Trenchless Technology: Planning, Equipment, and Methods, New York: McGraw-Hill Companies, Inc., 2013
Non-Circular Profiles
  • Product Catalogue
  • Line
Product catalogue, NC Line. Non-Circular Profiles, HOBAS Pipes International GmbH, 2014
ATW DVWK M 127 Static calculations for the rehabilitation of sewers and drains with lining and assembly process
DWA (German Association for Water, Wastewater and Waste), ATW DVWK M 127 Static calculations for the rehabilitation of sewers and drains with lining and assembly process (Part 2), 2010