Underground rehab

Three screens with a control panel to monitor the milling process in a pipe system
Trelleborg is a leading exponent of rehabilitation solutions for pipe and sewer infrastructure. It has recently added to that expertise with
several new technologies in its portfolio.

The last few warm summers have made it obvious; water is a scarce resource that should not be wasted through leakage. 


Aging water infrastructure, some dating back to the early nineteenth century, means pipes break and connections become leaky, causing valuable drinking water to soak into the ground. The estimated figure for global water loss is 30 percent; that is equal to one in every three glasses of water seeping into the earth.


Pipe and sewer repair is critical to preventing water loss. In the past, doing this meant complex construction work with roads, domestic connections, and structures needing to be torn apart and then put back together again. Today, trenchless pipe rehabilitation is becoming the more typical approach. It is quicker, more cost-effective and less disruptive. 


Hoses inserted into existing pipes and cured in place facilitate a repair. Using this method and covering the inside of a pipe with a continuous surface, a new pipe is created within the old one.

Light-chain inside a pipe


Innovative Sewer Technologies, or I.S.T., has been a leading exponent of this technique since it was founded in 1998. The company, based in Bochum, Germany, has become one of the most successful full-service providers for pipe and sewer rehabilitation, and was purchased by Trelleborg in December 2022.


Jörg Vogt, the founder of I.S.T and now Product Group Manager, responsible for the site in Bochum, explains: “We not only offer the consumables needed for sewer rehabilitation but also the equipment and machines required to perform the repair operation. There are competitors in the fields of milling or robotics or consumables, but there is no other company that can cover all three areas.”


Vogt, a qualified engineer in chemical and glass technology, initially sold only the materials required for trenchless pipe rehabilitation — hose liners made from various materials and impregnated with synthetic resins.


“In our early years, steam and hot water were used for the curing process. The disadvantage was that you couldn’t follow up the curing process,” Vogt explains. “So, we turned to UV curing after a few years. The advantage is that you evenly cure the inliner with UV light and at the same time can follow and control the process using cameras.” 


Trelleborg realized the importance of UV curing, and the I.S.T acquisition was therefore a strategic addition that strengthened Trelleborg’s position in the pipe repair market.


The Bochum facility manufactures light sources for a wide range of pipe diameters.


Luminaires with up to 1,000 watts hang together in chains in the middle of wheel constructions that pull the UV light chains through inliners at a constant speed with the help of winches. Precisely measured wheel sets fit different pipe diameters. For lateral house connections, the company offers LED light curing with just one curing head in sizes down to seven centimeters in diameter.

uv-light-source standing on the floor


There is also a range of milling robots to prevent the clogging of pipes and ducts. At the front end of a cutter there is a milling head powered by compressed air or electricity, driven through pipes at high speed. A zoom camera supports the operator who monitors and controls the milling process from a control panel.

There are around 80 people working at Trelleborg’s facility in Bochum. Inliners are rolled up, folded and sewn on two fully automatic manufacturing lines while technicians assemble robots and UV systems. In a separate area, application engineers experiment with new formulations to make inliners even more flexible and to further reduce curing times. Consumables stored on high shelves make the concept of a one-stop-shop for sewer rehabilitation a reality.


“We have a highly qualified and trained staff, high-quality materials and the best possible equipment,” says Vogt.

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This is an article has been reproduced from Trelleborg's T-Time magazine. To download the latest edition, go to: www.trelleborg.com/t-time