Tuesday, April 16, 2024

OSLO VAV TESTS FULL-STRUCTURAL LINER

Old, ailing water pipes become like new with a liner. Or is it too good to be true? Oslo VAV in Norway is now conducting its own tests on highly topical liners for excavation-free renewal of water pipes, thanks to technology funds from FHI. Pipeliner AS is the first in the test, with IBB 16 full structural liner from IBG HydroTech. Now Pipeliner is also developing a robotic technology for milling and sealing liners in house connections without digging.

Putting a liner in water pipes is a VA area many are interested in, but where few have taken the steps and gained their own experience. The City of Oslo VAV has now initiated its own tests, and will, among other things, investigate how fully structural liners can be installed in bends.

“Yes, we are going to look at water liners in bends. Both installing the products and to see what they can withstand and examine mechanical properties. This is very exciting.” Elisabeth Hovda said.

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Elisabeth is chief engineer and chair of the materials committee in the City of Oslo’s Water and Sewerage Department. She is the municipality’s chief responsible for the quality of the products used in the water supply.

This autumn (2022), the municipality is conducting its own tests on several types of materials and products in the Potable Water area. This will take place in a robust test environment that has been built with funds from a new fund for technology development at the Institute of Public Health (FHI). The funds are available to all municipalities.

Full-structural liner for water mains

One of the products Oslo VAV is carefully examining is a liner for the renewal of water pipes. Specifically, fully structural liners that are installed in an existing water pipe, but which after installation are completely independent of the existing pipe. In other words, there is no liner adhesion to existing pipes, but a product inflated and hardened to stand firmly in its own.

Here you may be a little surprised that this is presented as a novelty. Pipe renewal with lining is nothing new. This has been done for decades, but that’s on sewage pipes. Now we are talking about liner renewal of water pipes. It is quite a different ‘sport’.

“It is an important mapping. Renewal with liners on water pipes is completely new to us, and we need to acquire knowledge. We have the knowledge on sewer lining, but that is something else. It is not as similar as you might think.” said Hovda. “Lining of wastewater pipes is a mature market. On water there is unploughed ground. There are quite big differences between renovating sewage and water pipes with lining.” said Sales and Marketing Manager Tor Heggernes of Pipeliner AS.

The pipe renewal contractor headquartered in Bergen was the first of two
contractors to test their products and solutions for Oslo VAV. During the
autumn, Oslo VAV and Pipeliner have together tested the installation of IBB 16,
a liner system approved for use in drinking water.

Robot finds house-connections after lining

The liner system from Pipeliner and IBG HydroTech is approved for dimensions from 1,600 mm down to 300 mm. The manufacturer of IBB16 is in the process of obtaining approval down to 150 mm, which is expected to   be ready in October. On such dimensions, one quickly meets the number one challenge when it comes to liner renewal of water pipes – House connections.

In Oslo and Trondheim municipalities, the Renvann project is currently underway, where a few sub-projects are looking at various solutions for No-Dig renewal of water pipes using liners. As part of this, Pipeliner is in the process of developing a robot that will enable renewal with liners on House connections also.

The pre-installed water liner is 6 to 15 mm thick, depending on the dimension, pressure class and fall. As of today, it is not possible to have the IBB16 liner installed in water pipes with house connections without digging on the connections, but that is about to change. Pipeliner’s solution consists of a robot that is sent into a water pipe with a newly installed liner, it finds the existing house connection, mills up the liner and installs a plug that seals the house connection against the new liner.

The system will be ready for testing a prototype over the coming winter and will enable renewal with structural liner also on 150 mm diameter water pipes with house connection without digging. This is an important prerequisite for both Oslo and other municipalities to
be able to use lining on water pipes.

“It is not easy to find water pipes without house connections in Oslo.” said Elisabeth Hovda. “We talk to a lot of municipalities. Everyone is anxiously watching the outcome of this project. It is very positive that Oslo VAV is leading the way in renewing water pipes with structural liners. The capital has long been considered reluctant to try out new technology, but now they are leading the way. It is incredibly inspiring to be involved in development and testing together with such a large and strong environment, with a lot of different expertise. This is a development project for all parties. It is very educational to be a part of it.” said Tor Heggernes.

Pressure test to 21 bar

The IBB 16 water liner from Pipeliner & IBG HydroTech consists of two individual liner installations that becomes one full-structural liner. First a fibreglass liner is inflated and cured against the pipe wall with UV light. Then a felt liner with a PE coating is cured with steam and adheres to the fibreglass liner. Together they form a new pipe that is flexible enough to follow the pipe, even around bends. The IBB16 liner is used on pressurised drinking water pipes in pressure classes PN 10 and PN 16. After installation, the liner is
pressure tested.

“In normal installations, the liner is pressure tested up to 15 bar. Here we push it up to 21 bar. For us, it is very interesting to be part of a test like this. Out in the field on existing water pipes, it is hard to do tests like this. There everything needs to be under control and
to be correct. Here it is allowed to explore the boundaries and to fail a little. Then both we, as a contractor, and the municipality, as the water line owner, will be confident in the solution.” said Heggernes. Renewal with a liner is a necessary method for renewing the
drinking water network. There are a lot of bends on the water pipe network. Therefore, there is a need to know if there is good enough quality in these liner products. Will they help? For example, is it possible to install them in bends without too many wrinkles in the inner turn? These are the kinds of things being looked at here, and which are very important to gain knowledge about.” said Elisabeth Hovda.

Oslo VAV has set up its own test rig for water products, in the form of a container furnished with a jig for simulation of many different assembly situations, bends and types of products. The IBB16 liner is installed in a 22.5o bend of a ductile cast iron pipe. In the test rig, the pipe is divided in two longitudinally, so that observers can see exactly how the liner behaves in the critical inner side of the bend. “Straights are easy. It is in bends where the problems arise, and that is what we need to investigate carefully.” said Elisabeth Hovda. Later this autumn, a similar test will be carried out with a IBB16 liner in 45o bends.

The container has been built with funds the municipality has received from the Norwegian Institute of Public Health’s fund for technology development in drinking water supply. Here, FHI makes a pot of Kr5 million per year available for various types of technology development in the area. These are funds for which all municipalities can apply. Drammen municipality has also received funding from here, which has been used to test pipe-in-pipe systems for use in branch pipes from the main water line. Norsk Vann and the upcoming Water Centre at Ås have played key roles in the application process at both Oslo and Drammen.

Proud of the test rig

Elisabeth Hovda and her colleagues at Oslo VAV are very pleased with and proud of the test rig, not least for the opportunities it provides when it comes to exploring technology together with suppliers.

“We are so pleased! Skilled and creative people in our own mechanical department
have created a fantastically flexible test rig. Here we have a great opportunity, and we
have a great cooperation with two contractors and liner manufacturers. This is a new
area for us. We have no knowledge of this today.” said Hovda. “Can we give examples
of specific information we have received in the early phase of testing together with
the contractor? Very much so! Not only good product knowledge, but also a lot of
knowledge about the ‘water liner’ product type in general. What is it? How long should
it last? What about drinking water approval? What about what is happening in the EU
now, with new drinking water approval due to be completed in 2025? What about
installation? How much needs to be dug? Where is this product suitable? There are so
many water liners. We have been through semi-structural water liners, and we have
PU coatings. Collaborations like this give us unique opportunities to go deeper into the
products and see it towards what we know we need.” she said. “Where will Oslo VAV
be in this area in five years? That is a good question. By then we will know much more
about where and how it is appropriate to use water liners to renew our water supply.
We are now taking some important steps that give us competence and security so that
we know what we are doing when choosing renewal methods.” Said Hovda.

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