CRC-p Project: Smart Linings for Pipe and …...3 19-9-2019 Second draft Benjamin Shannon 4...
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CRC-p Project: Smart Linings for Pipe and Infrastructure State of the Art Literature Review on Spray Liners Civil Engineering
Transcript of CRC-p Project: Smart Linings for Pipe and …...3 19-9-2019 Second draft Benjamin Shannon 4...
CRC-p Project: Smart Linings for Pipe and Infrastructure
State of the Art Literature Review on Spray Liners
Civil Engineering
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Quality information
Document: Monash University CRC-P literature review on spray liners
Edition date: 011-05-2020
Edition number: 4.2
Prepared by: Benjamin Shannon, Rukshan Azoor
Reviewed by: Guoyang Fu
Revision history
Revision Revision date Details Revised by
1 20-09-2018 First section complete Benjamin Shannon
2 14-12-2018 First draft completed Benjamin Shannon
3 19-9-2019 Second draft Benjamin Shannon
4 24-03-2020 Final draft Benjamin Shannon
4.1 04-05-2020 Final edit Benjamin Shannon
4.2 11-05-2020 Final Benjamin Shannon
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CONTENTS
1.0 INTRODUCTION ............................................................................................................... 1
1.1 Background ................................................................................................................................... 1
1.2 History of spray-on liners ............................................................................................................. 2
1.3 Current status in Australia ............................................................................................................. 3
1.4 Objectives ..................................................................................................................................... 5
2.0 PIPE LINERS ...................................................................................................................... 6
2.1 Spray liners examined ................................................................................................................... 6
2.1.1 Scotchkote 3M 2400 ......................................................................................................................... 6 2.1.2 Subcote FLP II (Formally Fast-Liner Plus) UK – Radius Subterra .................................................. 8 2.1.3 Abergeldie Ultracore 301 structural epoxy ....................................................................................... 8 2.1.4 Acothane RF ..................................................................................................................................... 8 2.1.5 Other spray and structural liners ....................................................................................................... 8
2.2 Classes of pipe liners .................................................................................................................. 10
2.2.1 Class I (D) liner ................................................................................................................................... 10 2.2.2 Class II (C) liner and Class III (B) liner .............................................................................................. 11 2.2.4 Class IV I(A) liner .............................................................................................................................. 11
2.3 Installation process ...................................................................................................................... 12
3.0 Failure Modes of liners ...................................................................................................... 14
3.1 Performance under hoop stress ................................................................................................... 14
3.2 Hole and gap spanning ................................................................................................................ 14
3.3 Pipe bending ................................................................................................................................ 15
3.4 Adhesion failures ........................................................................................................................ 15
3.5 Liner buckling ............................................................................................................................. 16
3.6 Long-term failure modes ............................................................................................................. 16
4.0 Case studies ........................................................................................................................ 16
4.1 Somerville, New Jersey (Matthews, Condit et al. 2012) ............................................................. 16
4.2 Yarra Valley Water, Victoria, Australia (Yarra Valley Water 2015) ......................................... 18
4.3 City of Peterborough, Canada (Peterborough Utilities 2013) ..................................................... 19
4.4 Yorkshire Water, UK (Yorkshire Water 2018) ........................................................................... 22
5.0 Review on Experimental Testing ....................................................................................... 24
5.1 Short-term tests ........................................................................................................................... 26
5.1.1 Hole or gap spanning test .................................................................................................................... 26 5.1.2 Pipe hydrostatic pressure tests ............................................................................................................ 29
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5.1.3 Pipe ring tests (Parallel plate loading) ................................................................................................ 29 5.1.4 Liner adhesion tests ............................................................................................................................. 29 5.1.5 Three point bending test ...................................................................................................................... 30 5.1.6 Vacuum test or external hydrostatic test (Class III) ............................................................................ 32 5.1.7 Transverse shear tests ......................................................................................................................... 32
5.2 Long-term tests ........................................................................................................................... 34
5.2.1 Long-term pressure testing.................................................................................................................. 34 5.2.2 Bending Fatigue tests .......................................................................................................................... 34 5.2.3 Standard creep testing ......................................................................................................................... 35 5.2.4 Accelerated failure tests ...................................................................................................................... 38
5.3 Gaps in experimental testing of spray liners ............................................................................... 38
5.4 Critical issues that should be resolved for lining pipes ............................................................... 39
6.0 Review on Numerical modelling of corroded host pipes with defected liners .................. 39
6.1 Effect of geometry of a defect on host pipe ................................................................................ 40
6.2 Effect of the material properties of the host pipe on the pressure rating of liners ...................... 40
6.3 Effect of liner defects on the performance of the liners .............................................................. 40
6.4 Effect of ground movement ........................................................................................................ 42
6.5 Effect of creep ............................................................................................................................. 42
6.6 Gaps and future work .................................................................................................................. 43
7.0 Research questions identified through this review and discussions in the CRC-P ............ 44
7.1 General questions ........................................................................................................................ 44
7.2 Where to spray line as oppose to dig and replace? ..................................................................... 46
7.3 How do we assess success? ......................................................................................................... 46
7.4 What are the issues when spray lining in a test bed pipe? .......................................................... 47
7.5 Brief activity plan and how the questions will be addressed in the CRC-P ................................ 48
8.0 Acknowledgements ............................................................................................................ 50
9.0 References .......................................................................................................................... 51
1.0 INTRODUCTION
1.1 Background
Deterioration of buried water and sewer pipes is an emerging concern among many utilities in
Australia. A number of different techniques have been used to replace/renew these assets that
consist of a range of pipe materials. These techniques include open trench replacements,
replacement on new routes, pipe pulling and pipe bursting. The most common type of pipe
replacement method used in Australia is open trench replacements and this method includes
cutting and breaking of surface material and excavation of soil from the point of connection to
the main along the entire length of pipe to be replaced. However, this method of replacement
is very expensive when replacing pipes in congested towns and cities. Further, open trench
replacement of Asbestos Cement (AC) pipes can be done by removing the old pipeline and
replacing it with a new pipe. This requires removal and disposal of asbestos waste in
accordance with OHS Regulations and recently, as per Victorian WorkSafe laws (Scott 2015,
Genever, Allan et al. 2017). An alternative method is to lay a new pipeline adjacent to the AC
pipe and transfer any services across. This reduces the interaction between workers and AC
pipe, but leaves the AC pipe in the ground which remains the responsibility of the water
authority. Pipe bursting of Asbestos cement (AC) pipes in Australia is not permitted (as it
creates asbestos waste). Therefore, new low-cost pipe replacement or rehabilitation techniques
are needed for ageing water pipes. For ageing cast iron pipes, methods of relining that reduce
the cost of replacement, reduce the replacement time and increase consumer satisfaction are a
priority. Rehabilitation of old water pipes by spray liners is a relatively new practice in
Australia and recently, a number of Australian Utilities have begun trialling some of these
liners in their pipe networks. Spray liners for water pipe trials have only recently gained
momentum in Australia, and have suffered a few setbacks along the way towards
implementation. The United Kingdom is the most advanced country in modern spray liner
installation with two standards (ING 4-02-02 and WIS 4-02-01) for implementing spray liners
(UK Water Industry 2014, UK Water Industry 2014).
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1.2 History of spray-on liners
The spray lining of pipes has been around since the 1930s (AWWA M28 2014) in the form of
cement-mortar lining (CML). Cement-mortar lining was used to increase flow in cast iron (CI)
pipes from the loss of flow caused by tubercules. Portland cement was typically used and this
liner had the added benefit that the inner pipe surface was protected from oxidation and thus
effectively halted internal corrosion. From the 1930s, Australian cast iron pipes were lined in
situ with cement-mortar. The mortar was sprayed through a mechanical rotating head onto the
inner surface. The spray head was attached to an umbilical cord and pulled through the host
pipe whilst spraying. Depending on the spray, some disadvantages due to slumping and uneven
lining levels could be found, however the general procedure was of big benefit in extending
the life of cast iron pipes.
Cement-mortar liners are regarded as a Class I liner (AWWA M28 2014) or Class D (ISO
11295 2017), as they only provide corrosion protection. The cement mortar liner was found to
provide a small structural strength for the pipe (Robert, Jiang et al. 2016), however if the pipe
was of a deteriorated state, leakage could still occur through the cement-mortar liner (WRF
Report 4326 2018)
Spray on lining technology has advanced to the point where liners are now claiming to be Class
IV (Class A) fully structural liners, however in essence, structural spray on liners for pressure
pipes are in a developmental stage, where testing is still required for classification. Hence, most
of the spray liners used today would be classified as Class I, II or III (D, C and B).
Over 33000 km of water mains have been relined using polymeric liners in the UK (Ellison,
Sever et al. 2010). The UK has used semi-structural polyurethane liners for the past few years
(Yorkshire Water 2018), however due to tighter restrictions to customer pipe repair shutoff
times, the spray liners used in the UK have shifted to mainly Class I (D) liner for corrosion
protection. To reduce the shutoff time, liners are installed in less passes with a thinner lining,
hence cannot act as a semi-structural liner. As most Australian CI pipes are cement-mortar
lined, the idea of structural spray-lining as a method to reduce the likelihood of pipe failure is
more favourable than a Class I (D) corrosion barrier. Therefore, Class II (C) semi-structural
and above spray-liners are targeted to reduce leaks and failures.
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There are typically four types of spray liners applied these days on potable water pipes: cement-
mortar, epoxy, polyuria and polyurethane (Motlagh, Jain et al. 2013).
Epoxy spray was first used in the 1970s in the UK (Morrison, Sandgster et al. 2013). The spray
process is similar to cement-mortar lining where a mechanical spraying head, attached to an
umbilical cord is pulled through the pipe. The pulling and spray dispersion are monitored
throughout lining. Epoxy with better suited material properties (e.g. higher long-term tensile
strength) are capable of achieving semi-structural classification.
Polyurea is a type of polymer lining introduced in the late 1980’s. Polyurea can be specifically
formulated to meet different performance requirements. A rapid set and dry time can allow
quicker return to service for polyurea. Quick return to service is a key criteria for rehabilitation
of pipes (Hashemi and Najafi 2017).
Polyurethane uses a two part component system with an isocyanate and polyether polyols
(AWWA M28 2014). Polyurethane has a slower cure time than polyurea, however does still
provide a quick return to service time.
The three polymeric resins (epoxy, polyurea and polyurethane) are based on a two part solution
(Motlagh, Jain et al. 2013) with a base and an activator. The base and activator should be
different colours and produce a totally different colour when mixed together (UK Water
Industry 2014). The spray liners are all thermosetting polymers meaning once cured or heated
the liner is rigid and this process is irreversible.
Only three spray liners have been certified for use in potable water supply in the UK (UK Water
Industry 2018). These include 3M® Scotchkote liner 2100, 3M® Scotchkote liner 2400 and
Radius Subterra Subcote FLP II.
Yorkshire Water has recently used a fibre based spray coating by Spencer Coatings for their
sewer main renewals (Yorkshire Water 2016). This coating has recently been adapted for
pressure piping and will be tested further for potable water pipes.
1.3 Current status in Australia
The use of new spray-on liners in pressurised water pipes in Australia is minimal (not including
cement liners). The age of our pipes is relatively young compared with other countries and
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many pipe assets can be accessed as the pipes are buried under nature strips. As pipes are buried
closer to the surface (0.5–1 m depth) than countries such as USA and Canada (~2–2.5 m depth)
(WRF Report 4326 2018), the traditional dig and replace method is favoured. This is due to the
lower costs of digging trenches and the newer pipes have a known design life and higher
acceptance. Spray liners are also classified as non-structural and therefore carry the stigma of
less beneficial in pipe rehabilitation (Ellison, Sever et al. 2010). However, the use of spray
liners may be of benefit in harder to access pipes or delaying the removal and replacement of
a major asset buried underneath critical infrastructure. If a liner can increase a critical asset’s
life by a certain amount of years than a cost-benefit analysis may favour the renovation spray-
on liner rather than full asset replacement.
Further testing for spray-on lining for creep and whether a liner can survive the fracture of a
pipe under pressure is needed (Ellison, Sever et al. 2010). Independent testing and bending
tests under working pressure have only scarcely been tested (3M 2011). Also, testing of
connections through the liner needs to be trialled. The ability for a liner to function in the long-
term is crucial and more testing is required (Ellison, Sever et al. 2010).
A minimum cure time of 16 hours was used for epoxy resin as the resin continued to cure after
the initial 4 hours until touch dry. During the curing time a leachate by-product could enter the
water supply (Ellison, Sever et al. 2010). Typically water quality testing to (AS 4020 2018)
should be conducted by the manufacturer of the liner before using the liner for potable water.
Water quality testing should be carried out after liner installation before the pipe is placed into
operation again.
Yarra Valley Water (2015) conducted a case study on 3M® Scotchkote spray liner in 2009 and
2015. From the 2015 trial, 1727 m of pipe was lined at four locations. The liner was deemed
not suitable for pipeline rehabilitation due to the limited long-term structural capacity, however
was found suitable for use for pipes under busy roads or for AC pipes.
SA Water (SA Water 2018) trialled 3M® Scotchkote liner 2400 product on an asbestos cement
water main that had been failing. The purpose was to trial the strength of the liner. Poor
installation quality meant the liner was installed with several defects (thinner liner, ridges, gaps
around valves and hydrants, damage due to tools). The minimum pipe size to line was 150 mm,
however this size was not preferred. Costs of installation were similar to dig and replace.
Further failures were found in the liner and therefore the liner trials were abandoned. Other
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sections that were lined continued to function well to this day, however no conclusive evidence
could be attributed to whether that is due to the spray liner or the host pipe condition.
Sydney Water (Sydney Water 2018) conducted spray lining trials around 2013 on a semi-
structural liner. The liner did not block too many tappings (1 in ~20). Slumping and adherence
to wall issues were sighted. The liner trial was abandoned. The issues were blamed on
applicators. Also noted was shelf life of the liner was an issue (due to importation) and that
could have had an effect on the trials. Twelve mains were lined up to 250 mm in diameter.
However, problems in the liner surfaced after the report had been issued. One main failed twice
after lining, and the consensus was lining did not improve pipe life.
1.4 Objectives
The objectives of this literature review are to:
• Identify the spray lining products and current standards used for spray lining.
• Identify common failure modes of liners.
• Identify gaps in existing standards and the required further analysis and testing.
• Identification of problems and questions to be addressed in this project from case
studies, experimental testing, numerical modelling and industry experts.
The final objectives of the CRC-P project for Monash University are to:
• Review and develop guidelines and standards for the installation of semi-structural and
structural liners for pipes in Australia.
• Develop a decision tool for fit-for-purpose lining.
This literature review covers spray liners previously used and new technologies, classes of
liners, installation processes, failure modes of liners, case studies, results on experimental
testing, and numerical modelling.
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2.0 PIPE LINERS
2.1 Spray liners examined
For potable water pipes, there are many non-structural lining systems. Some of the liner types
are Abergeldie Ultracore 301 structural epoxy (spray liner), 3M Scotchkote (spray), Radius
Subterra Subcoat FLP II (spray), Polyurethane spray liner by ERA polymers in Australia and
Acothane carbon fibre spray (more spray liners are coming on the market). Brief details of each
liner are provided in this section. Details of each liner are shown in Table 2.1.
Spray liners are generally used to increase flow capacity, reduce water quality issues and
prevent internal corrosion. As typically corrosion protection spray liners are only 1 mm in
thickness, the structural improvement (tensile and shear strength) is insignificant, especially in
cast iron or steel pipelines. If the liner is increased in thickness this may contribute to increased
strength, however at the cost of hydraulic flow. If the concrete liner (typically 5 mm thick) is
removed before placement of the spray liner, a thickness of up to 5 mm could be sprayed
without any flow reduction.
2.1.1 Scotchkote 3M 2400
3MTM Scotchkote TM was significantly tested by (Ellison, Sever et al. 2010), however as of this
time has been removed from the market. 3M Scotchkote 2400 liner was the second attempt of
3M to improve the properties of the structural spray liner.
Originally 3MTM ScotchkoteTM 2400 liner was classified as a fully structural liner (Class IV),
however the class rating was downgraded to semi-structural (Class II to III) by 3M (3M 2015).
The product was recently removed from the market. The product is still in use today in select
water utilities and has suited their needs, provided installation was under strict quality control,
planning and quality workmanship. As the product is no longer available utilities are looking
for other spray lining for pipe rehabilitation.
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3M provided a calculator to determine a thickness required for their lining product, however
this has been removed from their website. The calculations were based on ASTM F1216 (2016)
and a captured image can be seen in Figure 1.
Figure 1: 3M thickness calculation. This has been removed from 3M’s website.
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2.1.2 Subcote FLP II (Formally Fast-Liner Plus) UK – Radius Subterra
Subcote FLP II (formally Fast-line Plus) is a solvent-free spray liner for potable water that
exhibits no shrinkage (Subterra 2010). The liner has been applied in countries such as UK,
USA, France, Czech, Norway, Russia, China, and more. The liner has UK Water Industry,
(2014b) WIS 4-02-01 approval in the UK. By applying the liner at different thickness FLP can
be classified from Class 1 (D) to Class 3 (B).
2.1.3 Abergeldie Ultracore 301 structural epoxy
The processes involved in using a spray epoxy liner may include: pressure washing of the
original pipe surface, muriatic acid solution followed by diluted bleach and TSP solution to
remove oils, pH test to see if the surface is neutral, heating up of the epoxy and spraying of the
epoxy and curing time of the epoxy. This product has been removed from CRC-P project
testing.
2.1.4 Acothane RF
Acothane carbon fibre by Spenser coatings (Spenser Coatings 2015) is a carbon fibre reinforced
solvent free hybrid polyurethane liner. The lining has been used for sewer applications and is
new to the potable water industry. The liner is not recommended for use in potable water as
water quality testing has not been passed as of yet.
2.1.5 Other spray and structural liners
Other spray liners for water and pressurised sewer will be examined on the basis that funding
is allocated for testing and testing locations are available.
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Table 1: Table of the liner information from different spray liner manufacturers.
Product name of the liner
Subcoat FLP II 3M scotchkote 169HB
3M scotchkote 2400
Ultracore Acothane RF
Type Spray Spray Spray Spray Spray Class 1-3 (depending on
thickness) 2 2-3 (C-B)2 3 3
Wall thickness (mm) 1–7 1.2–8.25 1.2–8.5 6- 20 1.5–6 Diameter (mm) 75–1500 80–600 100–610 Maximum installation length (m)
180 180 180
Max operating pressure (kPa)
Depends on thickness
1414 at DN150, 3.5 mm thickness
1.41 DN150 3.5mm thick liner
1600 (at 2 mm thickness)
Negative pressures Yes but depends on thickness
Liner material Polyurethane resin
polyurea polyurea Epoxy resin Carbon fibre polyurethane
Coating material Polyurethane resin
polyurea polyurea Epoxy resin polyurethane
Resin Polyurethane resin
polyurea polyurea Epoxy resin polyurethane
Abrasion resistance 46mgm/1000 cycles
Low (243 mg loss)
Installation procedure Spray resin mixed in head and heated to 20-35°C
Spray Sprayed hot
Installation Pressure (kPa)
NA NA NA NA NA
Bends 22.5 22.5 22.5 Curing method Ambient Ambient Ambient Ambient Ambient Installation time (h) Variable Variable Variable Variable Variable End sealing method FLP placed on end
using spatula/None
None None None None
Curing time 1 hour (30 sec gel, 6 min film, 12 mines cure for CCTV)
1 hour 60sec gel, 3 min film set, 10 min cure, total cure 1 hour
1-2 hours (24 h full cure)
~1 hour overcoating (24 hr full cure)
Suitable for AC, CI DI, CI, DICL, S, PVC
CI, DI, CICL, DICL, Steel
AC, CI Steel and concrete
Access pits required Yes Yes Yes, entry and exit pits
Cleaning the pipe Whirlwind Drag scraping Whirlwind see (UK Water Industry 2014a)
Water jet, rack feed boring, drag scraping or plunging.
Waterjet surface, Fill voids, chlorine wash, rinse, acid wash, final wash
Service connection reinstatement
Does not block fittings
Does not block fittings (some robot reinstatement)
Service connections are not typically blocked
Does not block fittings
Tested with AS/NZS 4020 or NSF61
BS6920, WRAS, Reg 31,
NSF61, AS4020 NSF/ANSI 61 No
Extra Information No melting transition from DSC. Glass transition 65°C
Valves and gates must be removed, abandoned valves/gates can be lined
Tensile strength (MPa) 40.61 (38.8) 14.21 39 48.31 34 Yield stress (MPa) 5 (tensile
elongation)
Tensile Modulus (GPa) (3.8% elongation) (1.3% elongation) Ultimate flexural strength (MPa)
661 (65.9) 251 58 971 89 (at 4 mm)
Flexural modulus of elasticity (GPa)
2.841 0.771 3.62 3.61 5.3 (at 4 mm)
Adhesive strength (MPa)
261 10.21 3.91 >18 (steel)
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Product name of the liner
Subcoat FLP II 3M scotchkote 169HB
3M scotchkote 2400
Ultracore Acothane RF
50 year allowable tensile strength (MPa)
1/3rd original strength
Hardness (Shore A) Not conducted 45-50 3 87 Shore D 89–90 Water absorption (21 days) ASTM D570
1.31% 1.31% (21 days)
0.53%
VOC None None None None Volume solids (%) 100 100 100 100 Bisphenol A BPA free BPA free Glass transition temperature (°C)
126 96
1 Results from testing WRF report (Ellison, Sever et al. 2010). Data could be inaccurate as coatings are unnamed. Also products may have changed. 2 Originally told as a Class IV liner, however 3M retracted this statement. 3 Results from testing EPA report (Matthews, Condit et al. 2012). Product may have changed since initial report.
2.2 Classes of pipe liners
Classes of pipe liners can be summarised as follows:
2.2.1 Class I (D) liner
Class I (D) liners are non-structural and are typically cement liners in water networks in
Australia. The main purpose of a Class I liner is to protect the inner host pipe from corrosion,
which can improve the hydraulic capacity (reduces build-up of corrosion products and
tubercles) for a structurally sound host pipe. The liner is typically sprayed, however no
structural support is given or used in calculation from the liner and the liner has minimal ability
to bridge joint gaps and corrosion holes. Leakage can be reduced marginally (only certain types
of liners), however it is assumed that Class I liners do not contribute to leakage reduction. The
use of Class I liners has been present in Australia since the 1940s. The UK has used epoxy
resin, polyuria, and polyurethane as Class I liners to improve water quality and flow, however
these are less commonly used in Australia.
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2.2.2 Class II (C) liner and Class III (B) liner
A semi-structural liner is Class II (C) or Class III (B) liner used inside a host pipe for structural
support, improving water quality and improving hydraulic capacity (varies depending on
previous condition and liner thickness). Class II liners require adhesion to the host pipe,
whereas Class III (B) liners are similar to Class II liners with the exception that Class III liners
are not reliant on adhesion to the host pipe. The semi-structural liners should be able to
withstand some external loads without the host pipe, such as hole spanning, however cannot
withstand the original operating pressure of the host pipe. Class II liners should be able to
extend the life of a damaged pipe to a certain extent (in this project we will determine life of a
spray liner through long-term testing). Most Class II liners adhere to the pipe, and polyurethane
or polyurea are typically used at present.
2.2.4 Class IV I(A) liner
A Class IV (A) liner is a fully structural liner and as a fully structural stand-alone pipe, the liner
must be able to withstand all of the following: internal corrosion of host pipe, isolated corrosion
pits in the host pipe, fully deteriorated host pipe, leaking pipe or joints, circumferential failures
and longitudinal splits. Class IV liners are suitable for CI and AC pipes in a deteriorated state
(through-holes, leaks and cracks may be present). Class IV liners should be tear resistant and
have the ability to hold water under the failure of the host pipe. To achieve this, the liner must
be installed correctly, with connections (tappings and fittings), joints and end seals that are
watertight. To ensure water tightness, end seals can be attached to pipe fittings directly,
tappings can be screwed into the pipe or adhesion must be strong to avoid water entering the
annulus between the host pipe and the liner. Fitting water tightness should be easier to achieve
in asbestos cement (AC) pipes rather than cement lined cast iron pipes (CICL) as typically the
pipe liner will be directly adhered to the AC pipe. Adhesion to connections, joints and end seals
must be adhered or sealed to the liner. The liner does not need to adhere to the pipe, however
water tightness must be satisfied. This can be achieved with self-tapping inserts that join the
liner and tapping together and seal them with a rubber seal. Typically, Class IV liners are CIPP
with glass or fibre reinforced layers not spray liners.
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Table 2 summarises the requirements for each class of liner described above.
Table 2: Recommended pipe class for different modes of failure in host pipes (adapted from (Ellison, Ariaratnam et al. 2015)).
Mode of failure
Estimated future condition of pipe
Class I Class II Class III Class IV
0 Minimal deterioration (no corrosion pits)
Yes
1 Isolated corrosion pits (including through holes)
Yes
2 Leaking joints Yes Yes 3 Vacuum Yes Yes
4 Longitudinal split (burst), Circumferential (broken back) failure
Yes
2.3 Installation process
The installation process of spray lined pipes follows the steps given below. The process can
vary depending on the liner manufacturer and application. For quality installation procedures
please see ING 4-02-02 (UK Water Industry 2014). A sketch of the process is shown in Figure
2.
1. The pipe is cleaned, dried and CCTV inspected.
2. The unmixed components are heated to a suitable temperature and recirculated within the
rig.
3. The spray lining applicator head is tested.
4. The flow rate of the mix is checked.
5. The umbilical is drawn out and through the pipe to be lined.
6. Once the umbilical is fed through the pipe, the applicator is attached.
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7. The operators undertake controlled spraying into a bucket to allow the operators to observe
the flow from the applicator for about 30 seconds to ensure the material is mixing and applying
evenly.
8. The umbilical begins to automatically retract through the pipe. The operators feed the
applicator/lining machine assembly into the pipe.
9. The applicator/lining machine is retracted at a set speed. The mix ratio, temperature and
speed are constantly monitored.
10. Once the applicator/lining machine clears the pipe the operators run the base material
through the applicator into a bucket to rinse the applicator. The applicator/lining machine is
then cleaned in acetone.
Large heated resin tanks
Pipe lining monitoring system
Winch/hose drum
Transfer pumps
Spray lining application
headLined pipeIn-line mixer
Entry access pit Exit
access pit
Umbilical hose (base, activator, air)
Lining rig
Cement mortar lined
pipe
Air compressor
and generator
Skids 3 part hose attachment
Figure 2: Spray lining process of an in situ cement lined pipe.
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3.0 Failure Modes of liners
The failure modes of pipe liners can be classified into several categories depending on the type
of structural performance of the liner. These main categories and the their associated failure
modes are discussed below as reported by Ellison, Sever et al. (2010).
3.1 Performance under hoop stress
The ability to withstand pressure is of primary importance for a liner. The liner needs to have
sufficient circumferential strength for this purpose, failing which the liner is likely to rupture
in the longitudinal direction. Therefore, the associated failure mode is tensile failure as related
to internal pressure by the following equation:
( )2
P d tFt+
=
where F is the tensile strength in MPa, P is the burst pressure in MPa, d is the internal dimeter
of the pipe in mm and t is the thickness of the pipe wall also in mm. This is required of a fully
structural liner (Class IV or A).
3.2 Hole and gap spanning
The ability of the liner to span hole, gaps and other weaknesses in the host pipe is vital to
prevent or reduce leaks, and to prolong the life of the pipe asset. The failure modes associated
with hole spanning are: punching shear, biaxial bending and tensile failure. In the first two
failure modes, the liner acts as a flat plate while in the third mode, the liner acts as a
hemispherical membrane. Stiff liners are likely to fail by the first two mode while flexible liner
materials are likely to fail by the third mode. This is required of a semi-structural liner (Class
II-III or C-B).
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In gap spanning, bending occurs in one direction (as opposed to biaxial bending in hole
spanning and therefore, the gap that can be spanned is generally shorter than the hole diameter.
For flexible liners, failure could also occur in tension similar to the hole spanning situation.
3.3 Pipe bending
In bending, similar to the host pipe, the most likely failure mode is the circumferential failure,
also known as broken back failure. Bending of the host pipe could take place due to differential
ground movement or external loads, and can impart stresses on the liner. The flexural modulus
and the tensile strength are important in resisting bending. Typically, bending is accompanied
by a gap that needs to be spanned by the liner and the pipe pressures could also influence failure
in this case (Figure 3). This is required of a fully structural liner (Class IV or A), and may not
be required for spray lining.
Figure 3: Contributing mechanisms for failure during bending with and without internal pressure (Ellison, Sever et al. 2010)
3.4 Adhesion failures
Adhesion of the liner to the host pipe becomes important to seal off leaks. In this sense a liner
that is well bonded to the host pipe is preferred. However, in the case of pipe fracture and
displacement, a well bonded liner might also fracture along with the host pipe. In this case, a
liner that is not well bonded could continue to hold water pressure while the pipe displaces
around it. This dilemma could be addressed by considering the main mode of operation of the
liner. For example, a liner installed in expansive soil in which the host pipe is likely to undergo
displacement, a structural liner not bonded to the pipe may be a better option provided the
leakages are taken care of. This is required of a semi-structural liner (Class II or C).
16
3.5 Liner buckling
Liner buckling can occur due to external loads or internal loss of pressure or vacuum conditions.
Vacuum conditions could occur in elevated areas and during pressure transients. Semi-
structural liners are generally capable of withstanding vacuum conditions. In flexible liners,
good liner adhesion to the host pipe could help withstand buckling under vacuum conditions.
This is required of a semi-structural liner (Class III or B).
3.6 Long-term failure modes
The presence of sustained loads may cause the liner material to permanently deform and also
to lose its structural properties. This effect can cause failure in the any of the above modes. The
effects of creep and strength degradation need to be investigated as applicable to each failure
mode.
4.0 Case studies
The following section gives three main case studies from literature from spray liners used in
water main rehabilitation.
The case studies are:
4.1 Somerville, New Jersey (Matthews, Condit et al. 2012)
Matthews, Condit et al. (2012) conducted a case study in Somerville, New Jersey on 3M
Scotchkote 269 spray lining on DN250 cast iron pipe. The lining was abandoned and deemed
to not be a Class III liner. Significant liner delamination, blisters, liner folds/bulges were found
after lining. The cause of delamination was attributed to improper application of the liner,
specifically the chemical reaction between the base components. An elevated moisture content
17
in the air used to spray the liner did not allow for the proper chemical reaction. The liner could
not perform after high humidity installations.
All leaks in the pipe need to be stopped before pipe lining. This was the cause for incomplete
liner coverage under tappings. The main was not put back into service, however if the main
was to be put back into service the estimated return to service time was 2 weeks (not same day
return), due to difficulties cleaning the main and reconnections. As cement liners would not be
removed in Australian pipes, one may expect that this cleaning process should be much lower
turnaround time. The authors also had an issue with long-term strength of the liner (1/3rd the
original strength (3M 2011)), based on creep testing.
It was noted that 3M liner installations in Perkasie, and Lansdale both showed similar
delamination, bulges and blisters to that seen in Somerville. Hole spanning generally covered
up to 18 mm, gap spanning was successful to some degree, however there were some sections
of the gap that were not covered. Material tested was found to only produce 36–64% of the
tensile strength and 3.6–40% of the flexural strength stated from the manufacturer’s
specifications. Liner adhesion was not measurable as the liner debonded in many locations.
The ridging effect was found to be more prevalent in the starting sections of lining the pipe.
Thickness varied from 0.9 mm to 13 mm, which would not be adequate for QC/QA. The liner
rig readout was not accurate in determining sprayed thickness due to the ridges.
Liner thickness is crucial, lining was ringed and the ridges with a smaller thickness were below
the designed 3.5 mm minimum thickness. Design values for 3M were 16 MPa tensile strength
and 22 MPa flexural strength (Table 4.1), well below the 3M design values. As noted by the
authors “it is critical to collect actual coupon samples of the liner in the field as part of the
QA/QC Program because cast samples (collected from the pail and/or rig) do not necessarily
reflect the “as-installed” condition of the liner.”
The final results indicated that the liner mixture was not consistent to what should have been
installed, hence the lower strength and longer setting times. This installation comes down to an
issue with quality control during installation.
18
Table 3 : Tables of data values from Matthews, Condit et al. (2012). Values are range of average between two testing samples. Field values are in brackets
Material properties 3M Scotchkote 269
Tensile strength (MPa) 19–24 (5.8–10.2)
Tensile modulus (MPa) 338–374
Flexural strength (MPa) 17–22.4 (0.8–8.8)
Flexural modulus (MPa) 720 (271)
Hardness 50–65 Shore D
4.2 Yarra Valley Water, Victoria, Australia (Yarra Valley Water 2015)
Yarra Valley Water (YVW) conducted a case study on 3M spray liner (Yarra Valley Water
2015). YVW relined a section in 2009 using an earlier prototype of the 3M liner (269). The
maximum pressure rating was PN10. The trial was halted when a relined main failed during
the evaluation period. As YVW was assured an improved product, a second liner evaluation
was trialled in 2015. Based on the cost analysis savings the benefits ranged from 0–41% cost
savings. Lining on different sized (100 mm and 150 mm) and different types (AC and CICL)
of pipes were trialled at four separate locations.
The difficulties found from installation included:
• Pipe cleaning
• Blocked customer connections
• Reopening service connections after internal diameter was reduced to 75 mm
• Developing a robotic cutter for 100 mm pipes
• Potential noise of the lining rig
• Spray-liner catching on previous repairs
• Spray-lining rig failures
The design parameters used in the trial were a PN rating of 16 (1.6 MPa), a life of 50 years and
a safety factor of 1.5. Failure of the Part A hose connection of the spray lining rig caused the
second layer to be abandoned due to time constraints. This liner held 800 kPa of pressure. Table
4.2 shows the testing results compared to manufacturing results from 3M.
19
Table 4: Tables of data values from Yarra Valley Water (2015)
Material properties Standards 3M Scotchkote 2400 Yarra Valley Water (2015) Tensile strength (MPa) ASTM D638 (2014) 39 29.4–36.0 Tensile elongation (%) ASTM D638 5 0.8–1 Tensile modulus (MPa) Yield stress (MPa) 28.5–32.1 Flexural strength (MPa) ASTM D790 (2017) 58 44.1–60.1 Flexural modulus (MPa) ASTM D790 3620 Hardness 87 Shore D Impact resistance 1.77 mm (joules)
ASTM D2794 (1993) 17
Impact resistance 6 mm (joules)
ASTM D2794 33
VOC EPA Method 24 0 g/L (in solid form) Abrasion resistance ASTM D4060 (2014) 193 mg loss 1000
cycles
Tg (°C) ASTM D7028 (2007) 96 Water Absorption ASTM D570 (2018) 1.31% over 21 day test Short term burst pressure (MPa)
ASTM D1599 (2014) 1.41 (DN150, 3.5 mm thick, unsupported liner)
Short term burst pressure (MPa)
ASTM D1599 (2014) 3.8–4.3 (4.0) (DN150, 8 mm thick, unsupported liner)
Short term burst pressure (MPa)
ASTM D1599 (2014) 0.94–1.7 (1.3) (DN150, 4 mm thick, unsupported liner)
Adhesion (delamination test)
Passed on a PVC pipe
Pipe stiffness test Adequate on 8mm not tested on 4mm
Gap spanning (hole) 6 mm Gap spanning (gap) 5 mm
Results were expected to far exceed 1.6 MPa to account for creep strength reduction. It was
concluded that spray lining was not equivalent of a new pipe, however, it could be appropriate
where conventional renewal is not possible, or is more cost effective than replacement. Liner
thickness of 8 mm was recommended for DN150 pipes and 6 mm thickness for DN100 pipes.
4.3 City of Peterborough, Canada (Peterborough Utilities 2013)
Peterborough Utilities (2013) used a newly developed ultrasound-based liner thickness
measuring device. The City wanted to extend the life of their existing pipe network as the pipes
were structurally deficient. The cement-mortar lining has a life of 30+ years and near the end
of life, so life extension through spray lining was planned to be used with the added benefit of
structural liner. Replacement costs are high, disruptive and challenging.
20
Peterborough worked with Caesars Infrastructure Services (CIS) to test ACURO’s liner for a
50–75 year life extension. The ultrasonic device was used to measure liner thickness and
contact of the liner and host pipe. Based on ASTM F1216 (2016) the liner thickness minimum
was 2.12 mm. As slumping can occur in the liner, the thickness measurements were taken from
the top of the pipe. Three or four passes were used to combat slumping due to gravity. The
resin feed rate and rate of sprayer controlled the average thickness applied by the computer
software used in the spraying rig. Post lining CCTV was used to validate installation. Service
reinstatement was not needed as no service connections were plugged.
The two cast iron pipes were used for lining that had experienced 11 and 9 documented water
main breaks over their 310 and 325 m lengths respectively. Road and lane closure, slug
discharge, flushing water and shock-chlorinated water were used during pipe rehabilitation. All
water main valves and stop valves were inspected so no water was allowed to leak back through
a faulty valve, leading to blistering or bonding issues.
Access pits for cleaning and lining were located at every 150 m and were shored with
dimensions of 2.5m x 2.5 m x 2 m deep. The pipe was disinfected according to AWWA
standard 651 (75 mg/L and 300 mg/L of chlorination solution for 24 hours), flushed (into sewer)
and water quality tested with chlorine residual, turbidity and bacteriological testing. Flushing
is continued until free of chlorine or less than 1.5 mg/L and turbidity less than 1.0 NTU.
Bacteriological testing was conducted after flushing at every 200 m or less. Site restoration
included road, sidewalk and grass restoration.
Testing was conducted on 300–400 mm samples cut out after lining. The ultrasonic device was
used to measure the thickness of the liner. However, the prototype ultrasonic device broke
down so was only used in the pipe samples, not the whole pipe length.
Liner failed to maintain 2.12 mm at the top of the pipe (12 o’clock), however average thickness
was maintained. The ultrasonic measurements were up to 21% higher than the physical
readings. To ensure the minimum thickness is met, the application process needs to be refined.
Flow increased due to reduction of tuberculation and hence water quality from iron
tuberculation was also significantly reduced. Costs were typically $800/m, however spray
lining costs were $662/m, to give a total savings of $94k. As the benefit was only 17% cheaper,
the semi-structural spray lining will be of benefit if the lined pipe’s life is extended by the 50
years stated. The lined pipe will also reduce the cost to repair pipe breaks each year and reduce
customer dirty water complaints.
21
Some of the problems encountered were:
• Main application of the product
• Cleaning technique must be chosen in advance, and techniques need to be
determined for different pipe types
• Stone cleaning left lots of residual stones in the pipe and connections
• Access to customer’s homes
• Plugged water meters
• Humidity in the pipe, blowing cool air into the pipe was found to eliminate this
problem
• Equipment reliability/ equipment breaking down
• Liner thickness at ends (stalagmites forming)
• Pit numbers and size (larger than CML pits)
• Protocol/practice needs to be used from start to end of lining project
• On-site communications failure
• Pipe cleaning
• Field operations
When cutting the liner for examination, the liner adhesion was broken and the liner came off.
Table 5: Information on ACURO IC-202 liner (Aquafix Acuro IC-202 2017)
Product name of the liner ACURO IC-202 Type Spray colour: grey Class II–III Wall thickness (mm) 1 mm+ Diameter (mm) 150 (tested) Maximum installation length (m) 180 Max operating pressure (kPa) 1600 (at 2 mm thickness) Negative pressures Liner material IC-202 two component polymeric resin (thermoset) Coating material Polyurea blend material Resin Polyurea blend material Abrasion resistance Low (243 mg loss) Installation procedure 82°C through sprayer head at a pressure of 20.7 MPa (min 13.8
MPa) and minimum 9.5 L/min, material temperature of at least 65°C. Pulling the spray head through the pipe from one pit to the other.
Installation Pressure (kPa) NA Bends Curing method Ambient Installation time (h) End sealing method None Curing time Gel time 7 sec
Tack free 30 sec overcoating (24 hr full cure) Suitable for Steel, cast iron and concrete Access pits required Yes
22
Product name of the liner ACURO IC-202 Cleaning the pipe At access pits 2–3 m long cut out for cleaning insertion. Clean
using scraping/brushing, high-pressure water, blowing stone Service connection reinstatement Does/did not block fittings Life expectancy (years) 50+ Tested with AS/NZS 4020 or NSF61 NSF61 tested Extra Information Structural lining requires more passes Tensile strength (MPa) (ASTM D638) 37.6 Yield stress (MPa) Tensile Modulus (GPa) Ultimate flexural strength (MPa) (ASTM D790) 57.4 Flexural modulus of elasticity (GPa) (ASTM D790) 1.882 Adhesive strength (MPa) 15.5 (steel) (ASTM D4541), >2.8 (concrete) (ASTM D7234) Elongation (ASTM D412) 10% Hardness (ASTM D2240) 72 (Shore D) Water absorption (21 days) ASTM D570
VOC None Volume solids (%) 100 Glass transition value (ASTM E1640, ISO 6721-7) (°C) 177 Abrasion CS-17/1kg, 5000 cycles (ASTM D4060) 59 mg loss Permeance, moisture vapour (ASTM D1653, method B) 0.001 perms Impact@24-26 mils (ASTM G14) 9.9 N-m Compressive strength (ASTM D695) 51.7 MPa Cathodic disbondment (ASTM G95) Pass, -3.0 volts @ 65°C (48 hours) Impact resistance (ASTM D2794) Direct-indirect > 18 N-m
4.4 Yorkshire Water, UK (Yorkshire Water 2018)
Yorkshire Water (2016) has been implementing spray liners for pipe rehabilitation for many
years to improve the lifespan of their underground sewers and water mains. Successful trials
were carried out for both sewer and water mains. Yorkshire Water (2016) typically used 3M
Skotchkote for relining water pipes to improve flow and reduce internal corrosion rather than
structural liner as many of their cast iron pipes were unlined.
In Yorkshire mining activity was prevalent, which lead to issues with soil and pipe movement
especially subsidence. Lead joints have smaller movement and hence can cause brittle barrel
failures of cast iron pipes at joints. For spray liners to span joints the joints must be close, a
thicker liner should be used, or an increase thickness at the joint.
To avoid shadow effects two coats, one lining in each direction were typically used.
Yorkshire Water has lined 90 mm to 1160 mm diameter pipe, using a different spray lining rig
head for different pipe sizes. 98% of the pipes lined were on non-CML CI pipes. Yorkshire
Water successfully lined 100 mm pressure pipe. No failures on the pipes lined have been
recorded. No leaks were recorded on 3M lined pipes for over 3 years. One pipe at Haddlefield
was leaking badly and coated. No leaks were recorded after coating.
23
The whirlwind system, which cleans, shot blasts and uses hot air to dry the inner surface of the
pipe, was used to clean unlined pipes. Valves and hydrants had to be cut in after lining. T
sections were lined through. New connections could be connected straight into the liner, as
long as followed correct tapping procedure. When a clean cut was made there were no flaking
or peeling of the liner. There were no problems with taste and odour. The total times for lining
were approximately two hours for cleaning and two hours for lining. If the mix ratios are within
5% there were no problems with curing.
Most failures were down to operations:
• Breakdowns, head stops
• Trying to line pipes that were too deteriorated
• Poor cleaning of the pipe
Comments on liner given by Yorkshire Water were:
• Need trained and accredited liner, contractor and utility to do lining so only quality
people can apply it.
• A ferrule will block if its saddle tapping <15 mm.
• UK has lined over 500 km in the last 3 years.
The main issues of problems realised by Yorkshire Water were:
• Poor Quality Control (not cleaned properly, not applied correctly)
• Poor Planning
• Poor Workmanship
For lining, it was recommended to follow WIS and IGN for general specifications. Poor
workmanship in applying the liner was seen to be the major problem. Need to quantify and
check quality control.
As the 3M product is no longer available, Yorkshire water is trialling Subcote FLP II as is the
CRC-P project. Their hope is to use FLP II in a similar way that 3M Skotchkote was used. If
Yorkshire Water still had the choice, they would have kept using the 3M product as they did
not see any major problems.
24
The case studies all emphasise that understanding of the liner, standard installation and testing
procedures need to be developed before widespread adoption of the new materials will be
implemented.
5.0 Review on Experimental Testing
The performance criteria for selection of spray liners to rehabilitate deteriorated buried water
pipes are examined in this section.
The following are a shortlist of benefits and downsides to using spray lining.
Benefits Downsides
• Trenchless technology
• Service connections
• Can provide some structural support
• Cheaper compared to dig and replace
• Not fully tested for structural
capacities
• Pipe preparation problems
• Long-term effects less studied
The following performance criteria have been determined for spray lining: ability to debond,
long-term leakage prevention, corrosion prevention, ability to bridge gaps/holes, inherent ring
stiffness (Class III), and water tightness. For the purpose of the CRC-P project we will be
examining spray liners for Classes II to III (semi-structural liner and possibly exceeding Class
III requirements).
Prior testing of spray liners has been conducted by manufactures, applicators, water utilities,
independent laboratories, and universities. The most common strength tests for liners include:
Tensile tests : Standard tensile test following ASTM D638 (2014). This test is typically
conducted by the liner manufacturer and researchers to test the tensile strength of the liner.
Flexural test: Standard flexural test following ASTM D790 (2017). This test is typically
conducted by the liner manufacturer and researchers to test the flexural strength and strain of
the liner.
25
Compression test: Standard compression test following ASTM D695 (2015). This test is
typically conducted by the liner manufacturer and researchers to test the compressive strength
and strain of the liner.
Creep test: Standard creep test following ASTM D2990 (2001). This test is typically
conducted by the liner manufacturer and researchers to test the creep reduction factor of the
liner. Testing is typically conducted for 10,000 hours.
Adhesion test: Standard adhesion test following ASTM D4541 (2009). This test is typically
conducted by the liner manufacturer and researchers to test the pull off adhesion strength of
the liner resin. Delamination tests according to ASTM D903 (2017) could also be used.
Other testing for in situ applications include:
Parallel plate loading tests: Standard ring compression test following ASTM D2412 (2011).
These tests are conducted to verify the compressive strength of the liner under vertical loading
such as traffic with assistance from the host pipe.
Hydrostatic burst tests: The liners are tested for maximum internal hydrostatic bursting
pressure. Tested after removal of host pipe. Tests are conducted according to ASTM D1599
(2014).
Hole-spaning test: The liner is tested to span a small hole simulating a corrosion pit. Hole
sizes increase in size to check liner responses. There are no standards available.
Joint/gap-spanning test: The liner spans over or a joint or gap between two sections of pipe
to determine the capability of the liner. Joint or gap may be removed for testing. There are no
standards available.
Pipe bending tests: Typically host pipe and liner are tested under 3-point bending to see
whether liner can survive a sudden circumferential break in the host pipe. There are no
standards available.
Creep rupture test: Standard creep rupture test following ASTM D2990 (2001). This test is
typically conducted by the liner manufacturer and researchers to test the long-term strength of
the liner. Testing is typically conducted for 12-15 specimens at different stress values until
failure.
26
Hydrostatic design basis (HDB) tests: Hydrostatic design basis ASTM D2992 (2018) tests
subject a minimum of 18 samples to differing internal pressures and record the time of failure.
This gives an indication of the stress loss in the liner over time. A good substitute for tensile
creep tests.
Pressure fatigue tests: Subjecting the liner to pressure transients to fatigue the liner are a long-
term test that may be beneficial for long-term strength approximation. To the best of our
knowledge these tests have not been conducted on CIPP or spray liners. There are no standards
available.
Water quality test: Standard test from AS 4020 (2018). This test is typically conducted by the
liner manufacturer, water utilities and researchers to test the water quality after liner installation.
The smaller scale tests seem to indicate the material properties of the liners are capable of
providing some structural support, however large gaps remain in the literature testing as to
whether all testing was conducted for a wide range of testing scenarios. Large scale testing
requires further testing and research. The above testing will be conducted at Monash University
(except hydrostatic design burst testing and Water quality testing) to determine generic
properties for spray liners. The following section gives information on testing conducted by
various researchers.
5.1 Short-term tests
5.1.1 Hole or gap spanning test
Hole or gap spanning tests are conducted to determine the ability of the liner to span a hole
(typically a corrosion defect, e.g. graphite hole in a cast iron pipe or weak cement due to
leaching in an Asbestos cement pipe) or gap (joint section or pipe repair, where liner has to
span a change in diameter) under certain internal pressures. A hole acts as a simulation of a
corrosion patch or a defect, generally circular, in the host pipe. A gap is a section of pipe, such
as a joint, where the pipe is not continuous and the liner has to bridge or fill this gap (e.g. joint).
Figure 4 shows an example of a hole spanning test for a spray lined cast iron pipe.
Outcomes, benefits and reasons why the tests are conducted:
27
• Ability of liner to contain pressure under a partially deteriorated host pipe
• Examine fit for purpose spray lining for small defects or leaks
• Determine whether a liner passes Class II requirement of hole and gap spanning
Figure 4: Hole spanning test of cast iron pipe with spray liner. Different sizes of holes were tested under pressure and vacuum conditions. Tests conducted at Monash University
Gap spanning tests or hole spanning tests are used to determine the maximum internal pressure
the liner can withstand through a hole in the host pipe. Short-term tensile and flexural properties
are used to determine the initial hole spanning capacity and long-term properties are used to
determine long-term hole spanning capacity. Numerous reports and testing conducted by
manufacturers have determined hole spanning capacities of spray liners (Ellison, Sever et al.
2010).
Ha, Lee et al. (2016) reported results of tests various tests on a spray liner manufactured by
Lining City Co., Ltd. in South Korea. For the hole spanning tests, it was reported that the liner
reinforced pipe showed no leakage from a hole of 5 mm in the host pipe under a pressure of 11
MPa. The authors concluded that the liner performed to adequately and conducted no further
test on hole spanning. Gap spanning tests were conducted by the authors by pressuring the
pipe with a continuous gap of 11 mm spanned by the liner material. It was reported that a blow-
out failure occurred during the gap spanning test. However, the pressure reading at failure was
not reported due to a loss of data. The setup of the hole and gap spanning tests are shown in
Figure 5.
28
Figure 5: Hole and gap spanning test setup. Image from Ha, Lee et al. (2016)
Most hole spanning tests with holes in the host pipe were successful for spray liner pressure
testing. The liner can withstand short-term pressures above what would be expected in the field
(provided the liner is of appropriate thickness). ASTM F1216 (2016) gives formulas to
determine the maximum hole spaning capability based on flexural and tensile strengths. More
testing is required to assess gap spanning and to a lesser extent hole spanning.
29
5.1.2 Pipe hydrostatic pressure tests
Laboratory short-term hydrostatic pipe burst tests have been conducted on pipe samples by
several authors using ASTM D1599 (2014).
FLP II pressure testing was conducted (Pipeline Testing Consultants Ltd 2018) recently in a
private document. The hydrostatic testing was conducted using external end clamps and threads.
Host PVC pipes were removed prior to testing. Five burst tests were conducted on DN150
pipes with either a 3 mm or 6 mm FLP lining. For a 6 mm thick lining, the short-term failure
pressure was 2.5 MPa (minimum thickness at failure was 4.82 mm). Short-term failure pressure
was smaller for a thinner liner 976 kPa (minimum thickness at failure was 2.25 mm). Modelling
needs to be conducted as to whether this failure stress is applicable for a fit-for-purpose liner.
5.1.3 Pipe ring tests (Parallel plate loading)
No information on testing spray liners with this test has been found in published literature so
far. Ring test specimens will be loaded until failure (including unloading cycles), as part of the
testing programme at Monash University. The pipe ring tests allow for examining rebound if
liner is compressed and are an important test to check compression failure. Pipe ring tests can
be conducted according to ASTM D2412 (2011) or AS 1462.22 (1997).
5.1.4 Liner adhesion tests
Pull off bond strength tests were conducted by Ha, Lee et al. (2016) and recorded an average
pull off bond strength of around 5 MPa. The schematic of the test reported by the authors is
given in Figure 6. As Adhesion varies with the different surface substrates, testing on an intact
substrate will not give exact results that would be expected on a CML or deteriorated pipe
surface. More testing into adhesion on CML surface is recommended.
30
Figure 6: Schematic of the pull-off bond test as reported by Ha, Lee et al. (2016)
5.1.5 Three point bending test
Pipe bend tests using 3 point bending were conducted (Pipeline Testing Consultants Ltd 2018)
on two pipe samples. Pipes were initially lined and a section of liner was removed to simulate
gap spanning of the liner. Bending of the liner was imposed via a hydraulic loading point,
however this caused shear failure in one test. To overcome this a pipe section was placed on
top to distribute the load. Failure was caused by crushing of the pipe; therefore, modification
of this test would need to be conducted to assess actual bending properties.
In three-point bending tests reported by Ha, Lee et al. (2016) the angular displacement, load at
failure and the horizontal angle (see Figure 7) were reported. A failure load of 4.3 kN with a
central displacement of 59 mm at a horizontal angle of 6.7° was observed at the failure point
of the lining material. Figure 7 summarises the experimental setup utilised for the tests reported
by Ha, Lee et al. (2016). Testing was conducted under no internal pressure, therefore are not
applicable for a typical water main bending failure.
31
Figure 7 : Experimental setup for the three point bending test conducted by Ha, Lee et al. (2016)
Tests were conducted tests on five samples for bending failure under internal pressure of 345
kPa (Ellison, Sever et al. 2010). The bending speeds were 200 mm/min (accidental) and 5
mm/min. For pressurised tests, external end flanges were used. This was not successful as water
entered the annulus of the liner and the host pipe upon bending failure effecting the results.
Test were of short length with only five samples greater than 300 mm in length (smaller than
the standard 5x diameter or 750 mm length). The bending tests conducted on 3M liner showed
there was a large sliding distance of the liner under no internal pressure (about 40 mm). The
bending tests conducted were found to be inconclusive.
Two possibilities were cited: (1) water leakage into the annulus is common and the liner can
survive a fracture, however fail to hold water and (2) lining holds water pressure, however the
liner tears if the pipe breaks. However, their main conclusion was that more testing is needed.
Overall bending tests were poorly conducted. Longer pipe lengths should be used to avoid end
effects. Pipes should be pressurised to a comparable pressure in the field (not low pressures
<200 kPa). Bending can be tested using either worst case scenario (fast bending with partially
intact host pipe) or another scenario (host pipe not intact). The authors believe the worst case
32
scenario should be examined, as this is more likely to occur for bending close to a ‘hotspot’
(Weerasinghe, Kodikara et al. 2015).
5.1.6 Vacuum test or external hydrostatic test (Class III)
Insufficient testing has been performed on vacuum or external hydrostatic testing, especially
for new liners on the market. To quantify a liner as a Class III the liner must be able to support
both external hydrostatic or soil loads and internal vacuum loads.
Testing conducted by Pipeline Testing Consultants Ltd (2018) for FLP II found that short-term
vacuum could be held for a liner provided that the thickness was high enough (6 mm). Further
testing or modelling should be conducted to determine what thickness would be required under
long-term conditions for satisfying Class III requirements.
Vacuum tests can be conducted for hole and gap spanning as well as to assess the levels of
adhesion of liner the host pipe, with a similar arrangement to that shown in Figure 8
Figure 8 : Potential test arrangement for vacuum test
5.1.7 Transverse shear tests
Ha, Lee et al. (2016) carried out tests to evaluate the transverse shear resistance of the liner
material. This was achieved by, moving two separate halves of the pipe through which a
33
continuous liner was installed. Figure 9 shows the experimental arrangement used for the tests.
The ends of the pipe were secured with flanges and a constant pressure of 16 kPa (very small
internal pressure) was applied while laterally displacing the pipe at a rate of 12.5 mm per hour.
At this rate failure occurred at a displacement of 38 mm after a period of 7 days. The internal
pressure in testing was very low and would not correspond to typical internal pressures found
in the field in Australia (>400 kPa).
Figure 9: Experimental setup for transverse shear test as reported by Ha, Lee et al. (2016)
34
5.2 Long-term tests
Literature review shows that the long-term study of pipe liners can be classified into long-term
pipe pressure testing, fatigue tests and standard creep testing.
5.2.1 Long-term pressure testing
No long-term strength results based on hydrostatic design basis (HDB) testing following
ASTM D2992 (2018) were found for spray liners.
5.2.2 Bending Fatigue tests
Ha, Lee et al. (2016) reported fatigue performance for a cyclic loading test in a three point
bending arrangement. A displacement control method was used to apply 10000 cycles at a
frequency of 1 Hz. The maximum displacement per cycle was maintained at 6.1 mm. The pipe
was pressurised to 16 kPa throughout the test. No leakage or failure on the liner was observed
at the end of the cycles.
The authors concluded good performance of the lining over the 105 cyclic loadings. The
experimental arrangement for the fatigue test is given in Figure 10. Further testing would be
required at larger number of cycles and at higher internal pressure.
35
Figure 10: Experimental setup for fatigue tests reported by Ha, Lee et al. (2016)
5.2.3 Standard creep testing
Ellison, Sever et al. (2010) found that for a polyurea sample undergoing creep testing, the
deflections measured in the submerged specimens was high. A low creep modulus reduction
factor was found. Flexural creep testing was conducted from Yorkshire Water after 1000 hours.
The initial flexural modulus was 500 MPa extrapolated to 7 MPa after 50 years (and 3 MPa for
a different liner). Resulting in a decline of over 70 times the initial modulus. Water absorption
during testing may reduce the creep modulus significantly. Therefore long-term strength is
critical to examine further for spray lining.
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Figure 11: Creep test results for 3M Skotchkote conducted by Yorkshire Water (Ellison, Sever et al. 2010)
Standard creep test results and creep rupture tests of spray liners are severely lacking. A
strength reduction loss of 70% over 20–50 years may not be acceptable for spray liners. Data
on creep and strength loss over time needs to be further examined. Unfortunately no creep
stress values were given to determine creep retention factor. Also, no spray liners in the field
have been examined at a later period for any polymer deterioration.
Kanchwala (2010) provides creep testing results for polyurea liners (Scotchkote 269,
Scotchkote 169 and Scotchkote 169HB) used or potable water pipes. The tensile modulus,
average creep modulus at 1000 hours and average creep retention factor at 1000 hours for the
three product classs tested are give in Table 6.
Table 6 : Short-term and creep tensile moduli for various Skotchkote products as reported by Kanchwala (2010)
Specimen Tensile Modulus ‘E’
(MPa)
Average creep modulus
at 1000 hours
Average creep retention
factor at 1000 hours
Scotchkote 169 600 95 0.16
Scotchkote 169HB 600 191 0.34
Scotchkote 269 507 83 0.16
Kanchwala (2010) concludes that the creep strain rates decrease very rapidly at the initial stage
and further deforms slowly after 500 hours of loading during the test. For the flexural creep
tests Kanchwala (2010) reported that, during the 1,000 hours of the test, the creep strain
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increased exponentially with time for first 600 hours. After 600 hours, the strain varied
approximately linearly with time.
Figure 12. Creep modulus and creep retention factor vs. time for 3M liner products. Modified from Kanchwala (2010)
Creep modulus and creep retention factor were found to significantly reduce with tensile
specimens under small stress (< 3% maximum tensile strength), see Figure 12.
The strain vs. time curves from Kanchwala (2010) were not smooth creep curves (not shown
here). Temperature was monitored throughout testing, however humidity seems to not be
monitored. As humidity changes, so may the test results. Further testing is required to examine
this effect.
Motlagh (2013) continued upon the tensile creep tests conducted by Kanchwala (2010) and
reported creep test results up to 10,000 hours. It was reported that the mean tensile strain for
the six different specimens was approximately 0.0925% after 2,000 hours of loading, 0.0625%
and 0.0966% for 5,000 and 10,000 hours of loading respectively. The tensile creep modulus
was found to reduce from 1,349 MPa (195,654 psi) to an average of 732 MPa (106,161 psi)
over the 10,000 hours of this experiment. However, the testing data shows a decending and
ascending trend. After 2,000 hours strain decreased and then increased after 5,000 hours. The
testing was not conducted in a temperature and humidity controlled room, thus this could have
caused the cyclic pattern seen in the results. The stress level exerted on the specimens was also
low (0.28 MPa, compared with a tensile strength >12 MPa). This may have had an effect on
their data. Further testing is required to get a better understanding of creep in spray liners.
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5.2.4 Accelerated failure tests
Accelerated creep tests allow for testing the potential effects of creep over linger time frames.
No results were found for accelerated creep testing for spray lining. Creep rupture and fatigue
testing results were not found in literature either.
5.3 Gaps in experimental testing of spray liners
According to ASTM F1216 (2016), for gravity pipes, the long-term modulus of elasticity
(flexural modulus) should be obtained for engineering design. It should be noted that the long-
term modulus of elasticity and creep modulus are two different concepts, although they have
been treated as the same. Further work needs to be conducted to check the differences between
long-term creep modulus and long-term strength. For pressure pipes, the long-term flexural
and tensile strength are required for the design of partially and fully deteriorated pipes,
respectively. Therefore, attention should be paid to the effect of creep on the strength (e.g.
tensile and flexural deterioration over time) of the liners.
Attention should also be paid for determining the correct liner type for each individual host
pipe. A specific liner type may not be suited for a specific host pipe. Condition assessment
should be performed to determine whether spray lining is suitable as a renovation method for
each individual host pipe.
The following information should be examined when determining a standard for semi-
structural spray lined pipes:
• Transient pressure
• Vacuum pressure
• Deflection limits
• Combined loading
• Long-term strength effect
• Strength effect due to water absoption
• Poisson’s effect (shrinkage)
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• Temperature effect
• Humidity effect
• Thrust effect
5.4 Critical issues that should be resolved for lining pipes
The following section gives some critical questions that arise from literature and
communications with spray lining users, manufactures and utilities. The questions are to be
addressed by the end of this project.
• A proper testing regime of spray liners has not been conducted.
• Long-term testing showed a reduction in strength/modulus over 70% for 20 years. This
needs to be examined.
• Samples removed from in-service pipes need to be examined for deterioration of
polymers.
• Many failures of liners were due to application errors.
• Spray liners were originally classified as fully-structural, however actual Class is not
identified.
• Problems encountered during installation can severely slow down installation.
• Installation procedures should be followed to avoid liner defects. A standard such as
ING 2-02-02 (UK Water Industry 2014a) should be followed, however changed to
incorporate the cement linings of Australian pipes.
6.0 Review on Numerical modelling of corroded host pipes with
defected liners
Minimal numerical modelling has been conducted on spray lining. The following section
combines both CIPP (cured-in-place pipe) and spray liner numerical modelling.
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6.1 Effect of geometry of a defect on host pipe
To develop mathematical relationships between the size and geometry of a hole in the host pipe
and the burst pressure of the liner, Guan, Allouche et al. (2007) carried out numerical analyses
of a host pipe with 230 mm external diameter and 12.7 mm thickness. Different geometries of
the hole were considered, including square, circle, rectangle and ellipse in both hoop and axial
directions. All the defect shapes had the same cross-sectional area. Results showed that
rectangle and ellipse defect shapes with the long axes in the pipe axial direction have a
significantly lower burst pressure than a circular defect.
6.2 Effect of the material properties of the host pipe on the pressure rating of liners
Guan, Allouche et al. (2007) numerically simulated the bursting pressures of a host pipe with
230 mm external diameter and 12.7 mm thickness. Two materials, namely, the cast iron and
PVC were considered for the host pipe and the defect in the host pipe was of different sizes.
Results showed that the predicted liner burst pressures for cast iron and PVC host pipes are
quite different when the defect size is relatively small (10 cm), but the predictions converge as
the defect size grows larger. This can be explained as follows: The host pipe and liner act
together to resist the internal pressure, with the host pipe providing confinement to the liner.
As the gap size increases, the confinement provided by the host pipe decreases and the internal
pressure is resisted mainly by the liner in the gap area.
6.3 Effect of liner defects on the performance of the liners
Different liner defects have been studied by researchers to investigate their effect on the
performance of the liners.
Allouche and Moore (2005) and Jaganathan, Allouche et al. (2007) conducted comprehensive
experimental and numerical studies to quantify the effect of longitudinal folds on the pressure
rating of a CIPP liner. They demonstrated that when a longitudinal fold is transverse to an
opening in the host pipe (cast iron) wall, the burst pressure is the lowest. Through parametric
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study using finite element analyses, Jaganathan, Allouche et al. (2007) established a
relationship between the geometry of the longitudinal fold and the critical internal pressure for
the liner.
Zhao (2003) carried out a study on investigating the effect of the variation of liner thickness
on the critical buckling pressure of the liner. In this study, the thickness variations of the liner
in both the longitudinal and circumferential directions are assumed to be sinusoidal and the
frequency and magnitude of the thickness variations were studied. For the case in which
thickness varies exclusively in the longitudinal direction, it was found that the buckling
pressure increases as the magnitude of the thickness variation increases. For the case in which
thickness varies exclusively in the circumferential direction, it was found that the buckling
pressure decreases as the magnitude of the thickness variation increases. For the case in which
thickness varies in both directions, the buckling pressure decreases with the increasing of the
frequency of thickness variation.
El-Sawy (2013) employed finite element method to investigate the inelastic stability of
cylindrical liners with localized wavy imperfections. A smooth interface between the liner and
the host pipe was assumed. The liner’s material is assumed to follow elastic-perfectly-plastic
stress–strain relationship. The effects of the different geometrical parameters of the liner on its
stability are studied. Results showed that as the yield stress increases, imperfection size
decreases, and liner thickness decreases, the liner buckling converges to the elastic case with
normalized pressure approaching unity. In addition, it was found that in general, the liner’s
normalized critical pressure decreases as the imperfection angle increases.
It has been known that oil derived gases permeate across the liner wall which during rapid
depressurisation produce external pressure that in many cases lead to buckling collapse of the
liner. Rueda, Otegui et al. (2012) simulated the buckling collapse including post-collapse
pressure drop of the high-density polyethylene (HDPE) liners. In the analysis, a very small out
of roundness was introduced to nucleate buckling. The contact between the steel pipe and the
HDPE liner was assumed to be frictionless and a uniform and linearly increasing pressure was
applied on the external surface of the liner. Results showed that the collapse of polymeric liners
in the presence of external pressure is adequately reproduced by the finite element modes with
hydrostatic elements.
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6.4 Effect of ground movement
Bouziou (2015) numerically assessed the effect of transient ground deformation on a ductile
iron pipe with a circumferential crack or a weak joint. Ground motion time records were used
as the input. Six deformation modes were investigated, including axial offset, vertical offset,
transverse horizontal offset, lateral rotation, vertical rotation and torsion. Numerical results
indicated that most dominant form of deformation occurs in the axial pipeline direction.
To characterise the pull-out capacity and investigate the failure mechanisms of pipelines with
circumferential cracks or leaking joints, lined with the cured-in-place liner, Argyrou, Bouziou
et al. (2017) developed a one-dimensional finite element model to simulate axial tension tests.
The lining and the pipeline were modelled as beam elements while the interface between the
pipe and lining were represented by nonlinear springs. For boundary conditions, one end of the
numerical model was fixed while tensile displacements were applied at the other end. It was
found that numerical results are in good agreement with the full-scale test results.
Vasilikis and Karamanos (2012) employed advanced nonlinear finite element method to
investigate the mechanical response of the thin-walled liner pipe subjected to bending and
determine the deformation of the lined pipe at which the liner wrinkles. 20-node brick elements
and shell elements were adopted for the host pipe and the liner respectively. Numerical results
showed that Separation between the host pipe and the liner occurs at the compression zone
(Detachment), leading to liner buckling in the form of wrinkling. It was also found that the
behaviour is characterized by a first bifurcation in a uniform wrinkling pattern (small values of
detachment), followed by a secondary bifurcation (lager values of wrinkling amplitude).
6.5 Effect of creep
To study the long-term performance of the structural liner installed in deteriorated pipes, Zhao
(1999) and Zhao, Nassar et al. (2001) numerically investigated the creep-induced buckling of
constrained CIPP liners subjected to external pressure and the influence of geometric
parameters on liner buckling. Both the one-lobe model and the two-lobe model were
considered. In the numerical models, the compressive creep properties determined by Lin
43
(1995) were employed. Based on the numerical results, a liner buckling model relating critical
time to the dimensionless pressure ratio was proposed.
Zhu and Hall (2001) simulated the contact conditions and stresses which evolve as a thin-
walled polymeric pipe liner deforms under uniform external pressure, for various pressure
levels, material properties and geometric parameters (e.g. ovalities, gaps, etc.). Flexural
properties and compressive properties (Up to 3,000 hours, Guice, Straughan et al. (1994)) were
used for short-term and long-term buckling, respectively. It was found that the larger
normalised contact forces and contact areas associated with thinner liners correspond to the
higher enhancement factors and the larger contact area for thinner liners results in a shorter
span for the lobe, while the normalised contact force results in a reverse moment at the centre
of the lobe. It was also found that compressive material properties appear to be appropriate for
liners with low ovalities and gaps with no longitudinal imperfections, especially for liners with
lower dimensional ratio values.
Guan, Allouche et al. (2007) employed the results from the tensile creep testing up to 5,000
hours, and investigated the liner creep behaviour for a structural liner installed in a cast iron
host pipe with circular defects. It was found that creep resulted in an increase in the predicted
displacement by 70%-105% and the relative contribution of the creep effect to the displacement
of the liner increases as the defect size decreases.
6.6 Gaps and future work
For design of spray liners, there currently no standards available. Design standards ASTM
F1216 (2016) has been applied for spray lining in the past, however this is not recommended.
The current design standards/guidelines only support either circular or rectangular holes in the
host pipe and both standards are not able to consider the impact of an oval or irregular shaped
defect and did not consider the material properties of the host pipe. In addition, no numerical
study has been conducted to consider the inclined rectangular/elliptical holes or cracks in the
host pipe.
In this research project, numerical investigations will be carried out to determine the maximum
size of the defects that a liner can tolerate. The defects could be corrosion pits or cracks with
different sizes, geometries and orientations. The effect of different liner defects (uneven
44
thickness, creep etc.) on the pressure rating of the liner will also be studied. Apart from the
above, the behaviours of the corroded host pipes with defected liners subjected to ground
movement and creep will be investigated.
7.0 Research questions identified through this review and discussions
in the CRC-P
The following research question were identified through this literature review and discussions
with project members. These questions will be addressed in this CRC-P project and a brief plan
activity plan is given in this section (Section 7.5).
7.1 General questions
How do we assess if water is not moving through the cement mortar liner (CML) in between
host pipe and spray liner?
• CML is porous and can transfer water quickly whilst under pressure. Water can travel
through continuous CML to find exit point through an existing leak hole. This was
found to be the case from initial testing. Can this be avoided?
• Is the CML continuous at each joint? Or will a break in CML be formed when spraying?
If the liner was installed in situ then there is no guarantee that the joints will have been
bridged. If the CML liner was factory lined the joints will not be covered. Therefore,
testing to determine this bridging effect should be investigated. Will this have an impact
on previously leaking cast iron?
• Assuming if we totally isolate CML from water what happens to CML when it dries
out? Does the CML keep similar strength properties and also still function as a
corrosion barrier?
• What level of water transfer through the CML is acceptable for a fit-for-purpose
product?
45
Adhesion issue (where in the pipe does this apply in a pipe - between the barrel and the lining
or/and the connection and joints) needs to be addressed for Class 2 (ISO Class C) or Class 3
(ISO Class B) liners.
• Do spray liners need adhesion to host pipe? If not actively seeking adhesion, how do
we validate that the leak has been blocked? Adhesion is more of a consideration when
a thinner coating is applied (usually to improve water quality issues), especially in large
diameter pipes. If we are lining to produce a Class III liner this should not be affected.
• If so, how much and what adhesion is needed for fittings or ends? There are specialised
end and fitting treatments that should be standardised in Australia to ensure quality
control is met.
• Is adhesion an issue for protruding fittings or tapping bands? How would the liner cover
the CML or block the fittings? Is there a way to quantify this?
• Is adhesion needed for vacuum pressure? This will depend on thickness of the liner and
is a prerequisite for a Class III liner.
Long-term strength is a main issue for suitability and product life evaluation.
• What is long-term? For the water industry it may be 10 – 20 years life extension, not
80 – 100 years.
• What is the reduction in strength of the liner over time?
• Will larger thickness be needed due to strength loss over time?
• Long-term performance should be factored in at the design stage. However, there are
not many long-term testings on spray liners that have occurred. Will a standard tensile
creep/creep rupture test or hydrostatic design burst test be applicable? Manufacturers
of liners should conduct long-term tests for design.
How do we repair a section of spray liner that has failed or needs replacing?
• If the host pipe and liner have failed is it satisfactory to replace that portion of the pipe,
or does the whole pipe need replacement?
• How to replace the damaged section of the liner?
• Is there a standard needed to repair a pipe that has been spray lined?
46
• How to maintain watertightness after failure?
• How to remove a section of the pipe without damaging the liner?
• How to ensure other sections of liner are not fractured and put back into service after
repair?
• Are there general pipe fittings that can block water from entering the CML (at ends or
joints)?
• Are there any innovative way to maintain watertightness after repair?
7.2 Where to spray line as oppose to dig and replace?
• Condition assessment is crucial.
• How do we assess the condition of the pipe for application of spray lining?
• How do we determine when lining is a viable solution i.e. what is the tipping point of
host pipe condition?
• How to select pipes in need to rehabilitation to apply fit-for-purpose lining?
• How to reduce leaks in pipe, thus reduce corrosion rate/increased life?
• How to spray line pipe in a hard-to-excavate area?
• Is the cost of relining approximately 50% of traditional dig and replace?
• How many years does spray lining increase the pipe life by? The industry may be happy
with 10 – 20 years depending on the pipe asset to renovate. The client’s requirements
should be taken into consideration at the design stage. The longer the life expectancy–
the thicker the spray lining.
7.3 How do we assess success?
• Reduction of leaks (system approach – with minimum night flow assessment, sensing,
modelling and leak detection).
• Hole and gap spanning capability.
• Non-destructive bonding tests and monitoring – to be proposed by UTS.
47
• Need to ensure spray liner coverage is complete over CML, including tappings and end
connections.
• Liner thickness measurement, the liner will typically fail from the weakest (thinnest or
defect) point.
• Are bending tests (Class IV) suitable for small diameter pipes (<DN300), when a spray
liner is not technically Class IV liner?
7.4 What are the issues when spray lining in a test bed pipe?
• Cannot test to extreme pressures in case the test bed host pipe fails (e.g. host bed has
large defects may not suitable for spray lining). What pressure should we apply to the
lining? Need a factor of safety over the initial maximum allowable operational pressure
(MAOP). If the condition is so poor, then the section should not be considered a suitable
candidate.
• Testing of liner for properties would require destructive testing, however this is not
recommended until repair methods are known.
o Is there any non-destructive assessment (NDA) method to assess deteriorating
strength (tensile, flexural or adhesion)?
o Can monitoring instruments be placed in pipe before or after lining? Note: It’s
probably best to test after lining if they have to be recovered.
• Adhesion and leakage of the liner should to be monitored using NDA methods
(measurement of bonding strength or movement of liner?).
• Debonding of the cement mortar liner (CML) could occur if pipes were CML in situ.
Any ‘loosely adhered’ CML should/would be removed during the cleaning process.
• Adhesion of liner should be great enough for sample to be classified as a minimum
Class II (Class C in ISO)
• How do we interpret the lab results to the field (related to large diameter pipe) – Non-
destructive testing:
o Any condition assessment work prior to lining can be compared with CA after
lining.
o Leak detection methods of liner should be used as checks (Sahara leak report,
minimum night flow) compared with after lining leak report.
48
o In situ pressure testing results compared with results from laboratory testing and
numerical modelling.
o How to compare adhesion laboratory tests to NDA adhesion tests?
o Long-term strength results to determine maximum hole and joint spanning
capabilities in test bed pipe (based on condition assessment hole sizes).
7.5 Brief activity plan and how the questions will be addressed in the CRC-P
General questions will be addressed throughout the testbed installations in the CRC-P project
and thorough testing by Monash University and liner manufacturers. For the in-depth test plan
conducted at Monash, please see “CRC-P Monash Project Plan”. The testing plan will follow
the tests examined in the review on experimental testing (Section 5.0).
Cement Mortar Liner (CML) – Through initial testing, avoiding all water transport through
CML will be extremely difficult. However, it was shown that spray liners bridged holes and
could sustain pressures (much higher than operational pressure) with a defect in the host pipe,
with water travelling through the CML. Therefore, best coverage in the field will be prioritised
and lined pipes will be judged based on leak reduction. Further monitoring and testing will be
conducted throughout the project.
Adhesion – Adhesion is not required for spray liners to function, however, frictional adhesion,
and no shrinkage is important. This will allow liners to sustain a vacuum pressure and not
debond from the CML. If liners allow water to transfer between the CML and liner, they will
not be successful in reducing leakage. Liner sealing is important and this can be done through
end sealing of the pipe, using liner resin, and also using a thicker liner at the joints, for better
liner coverage. These will be further examined in the CRC-P.
Long-term properties of liner – Long-term testing of spray liners is difficult to find.
Hydrostatic design testing (ASTM D2992 2018) will give inconsistent results (as thickness can
vary causing stress concentrations) and therefore may not be the best test for long-term strength.
Creep rupture testing (ASTM D2990 2001) will be conducted to determine liner strength
deterioration curves. This will give crucial information when designing spray liners for long-
term.
Repairing of a failed spray lined pipe section – Repairing spray liner sections will be
examined in the trial sites, as section of pipes will be removed. At this stage, as long as cutting
occurs with a sharp rotary saw (not increased pressure on the liner) cutting is ok. Ends can be
49
sealed with resin if needed. However, selecting the correct liner thickness and type should be
a priority to avoid spray lined pipe failures (host pipe fully deteriorated).
Where to use spray liners and how to assess success? – Standards and renovation
frameworks need to be improved to determine where to use a liner and this will be examined
in the CRC-P. A lining decision tool, based on liner decision framework for small and large
diameter pipes will be created to choose the fit-for-purpose lining solution. Accessing success
will be based primarily on leak reduction. This will be measured before and after lining.
Secondary benefits from reducing leakage will include reducing internal corrosion. Therefore,
if renovation/replacement costs are reduced along with leakage reduction, the life of the host
pipe is increased, be can measure success based on cost improvements and minimum customer
disruptions. This will be examined with further lining trials.
Monitoring of trial sites in CRC-P – Lining thickness variation will be measured by UTS and
the robot they are developing for the CRC-P project. Leak monitoring and thickness
measurements will be conducted to access success in the pipes lined through the CRC-P project.
Monash will examine test results from literature, laboratory testing, trial sites and numerical
modelling to devise a decision tool based on fit-for-purpose pipe renovation with spray liners,
on what pipes are suitable to renovate, the liner thickness required and the expected lined-pipe
life. This tool can be used by water utilities to make an informed decision based on their
renovation/rehabilitation preference and business case.
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8.0 Acknowledgements
The smart linings for pipe infrastructure project (CRC-P) is a collaborative project run by
Water Services Association of Australia (WSAA) and funded through the Australian
Government collaborative research centres program and the following partners, Abergeldie
Watertech Pty Ltd, BASF Australia Ltd, Bisley & Company Pty Ltd, Calucem GmbH, Central
Highlands Water, Central SEQ Distributor-Retailer Authority (Urban Utilities), Coliban
Region Water Corporation, Downer, Hunter Water Corporation, Hychem International Pty Ltd,
Icon Water Ltd, Insituform Pacific Pty Ltd, Interflow Pty Ltd, Melbourne Water Corporation,
Metropolitan Restorations Pty Ltd, GeoTree, Monash University, Northern SEQ Distributor-
Retailer Authority (Unitywater), Parchem Construction Supplies Pty Ltd, SA Water
Corporation, Sanexen Environmental Services Inc, South East Water Corporation, Sydney
Water Corporation, The Australasian Society for Trenchless Technology, The Water Research
Foundation, UK Water Industry Research Ltd (UKWIR), University of Sydney, University of
Technology Sydney, Ventia Pty Ltd, Water Corporation, Yarra Valley Water, City West Water
Corporation, Nu Flow Technologies.
Research Partners are Monash University, University of Sydney and University Technology
Sydney (UTS).
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9.0 References
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