BRAWOLINER® 3D is becoming increasingly popular as a liner of choice amongst many drainage maintenance and repair companies across the UK. This happened to be the case on a project to rehabilitate a small part of the foul drainage system at a food processing plant in Lincolnshire located between Spalding and King's Lynn.
The problem being experienced by the plant was that a 61 m long, 150 mm diameter foul water pumping pipeline that is in constant use during factory production was in need of urgent rehabilitation. Whilst the work itself at first did not appear to be too difficult, one of the main obstacles to completing the installation was that access to the pipeline could only be achieved during scheduled shut down periods at the food processing factory or between working shifts when the pipeline was inactive. This meant that a rehabilitation system was needed that was quick and easy to install whilst providing a significant ongoing operating life for the pipeline. The food factory’s main contractor employed Peterborough-based drainage contractor DALROD to provide the solution.
Investigation of the foul water pump pipeline from the factory end to the pump pit revealed that due to access difficulties the short length of pipe had to be handled as two separate sections. Despite being only 39.5 m long, the more difficult section of pipe in need of rehabilitation had in just this short length some 10 mostly 90o bends that had to be lined without detriment to the capacity of the pipeline. Furthermore the pipe also had problems not only related to its ongoing operations.
A previous attempt to rehabilitate the pipe, undertaken by a different contractor, had left the pipe with varying internal diameters, with in some areas the poor liner quality reducing the nominal diameter by up to 50%, even over this relatively short length. This meant that the ‘old’ liner had to be successfully negotiated by any subsequent rehabilitation technique or the capacity reduction addressed. This is why DALROD chose to utilise the BRAWOLINER 3D lining system, provided in the UK by Peterborough- based C J Kelly Associates.
The BRAWOLINER 3D liner system was developed especially to meet the demands of pipes where there are big dimension changes or situations where several diameter jumps occur over one pipe length. Over dimensions from DN 100 to DN 150 the seamless textile liner adjusts itself to every pipe diameter during the installation process without operator intervention, giving a crease free finish to the cured liner.
The technology behind the liner’s ability to achieve such an installation is unique to BRAWOLINER. The liner material comprises an extremely flexible polyester-loop construction which allows a huge lateral stretch, without compromising the final liner structure. In addition to the multi-diameter capability, just like the proven BRAWOLINER, the new 3D Liner is also capable of lining bends of up to 90o without folds or wrinkles. This means that BRAWOLINER 3D is an ideal renovation solution for difficult sewer systems. BRAWOLINER 3D is available in the nominal diameters from DN 75 to DN100 and DN100 to DN 150 and is available in lengths of 25 m, 50 m, or 100 m. Also available is a larger diameter version for pipes from DN 150 to DN 225.
The limitation on access time for the liner installation at the food factory meant that the work had to be completed as quickly and efficiently as possible. Initial planning of the operation showed that this could only be achieved over the course of two shifts. However, after careful examination of the CCTV footage and consideration what needed to be achieved to negate the effects of the previous liner it was decided that the work would need to be done over four (4) working shifts within the available shut down times and shift patterns.
Within this shift availability the majority of the work load comprised mobilisation, cleaning and preparation before the actual installation of the liner. Once on site with the 39.5 m section of the pipeline cleaned it was necessary to deal with the previous liner problems before any new liner could be installed. The CCTV showed that the ‘old’ liner ran over a length of some 12.5 m but that it was heavily wrinkled and at some of the bends the liner protruded into the pipeline significantly, hence the up to 50% loss of capacity. The situation was also not helped by the fact that some of the host pipe bends were fabricated on site during installation with welds etc that meant they did not run smoothly around the desired curve.
As it was not possible to remove the old liner from the pipe, a technique had to be employed that would minimise the impact of the ‘old’ liner on any subsequent rehabilitation process. This was achieved by heating the ‘old’ liner by inserting a calibration hose through the lined section. The hot box was then run up to its maximum operating temperature to soften the existing liner. Once this was achieved, the pressure within the calibration hose allowed the ‘old’ liner to be reshaped to fit closely to the host pipe, eliminating the obstructions and wrinkles of the original lining process. At this point, to ensure the ‘old’ liner did not slump back into the pipe, the pipe was flushed with cold water to cool the system and reset the ‘old’ liner into place. The pipe was now ready to take the new Brawoliner 3D installation. However, at the time chosen to undertake two of the work shifts conditions were frosty with temperatures as low as minus 15 degrees. A typical shift comprised a start of work induction commencing at 2.00 am, then work started at 3.00 am with the shift completing by 4.00 pm the next day.
A further problem encountered on the project that made the installation more difficult than had initially been expected was that there was poor access to the upstream end of the pump line. The exit of the 39.5 m length of pipe being liner was higher than the height of the Brawoliner inversion drum so a platform arrangement had to be conceived that would allow the inversion to take place from the right height. Also the frosty working conditions caused problems with the mixing and impregnation of the BRAWOLINER resin. The fact that the work had to be scheduled around the factory shut down times meant that DALROD’s crews could in no way avoid working in the frosty conditions. However, experience always tells and the aforementioned difficulties were overcome by transferring the liner preparation work to within the factory building to allow the ambient temperature to come up to an acceptable level so as to allow the impregnation of the resin mix into the liner material to be smoother and quicker which also allowed for the project to be completed in a timely fashion.
The range of equipment on site that was used in support of the lining effort comprised a BRAWOLINER Air Drum for the liner inversion, a Twin Hot Box to control temperatures during the installation, and other associated BRAWOLINER instillation equipment. Ultimately, the Brawoliner 3D installation process itself took just 6 hours including resin impregnation, liner inversion into the host pipe and curing, which proved to be a highly efficient process.
According to Mike Pollard of DALROD: “In spite of the short pipeline length involved this turned out to be a technically challenging, even fiddly, job but using the BRAWOLINER 3D system and the associated hot box installation technique, the product used ultimately made the job much simpler. The weather conditions caused issues but were overcome by methodical thinking and transfer of the preparation operations indoors. The project was undertaken over four shifts as opposed to the two as initially thought due to the problems created by the previous lining effort. Ultimately, after all the prep work the new Brawoliner was installed in a short time with a very smooth finish and the project as a whole was successfully completed and brought in on budget. The video of the completed project is available to view on our website at www.dalrod.co.uk for anyone who would be interested in seeing it.”
Commenting on the project for BRAWOLINER, John Kelly of C J Kelly Associates said: “We are very pleased that The BRAWOLINER 3D product was particularly useful to DALROD in enabling them to complete this challenging project successfully. This is exactly the type of situation that the product is designed to handle with minimum fuss, a small site footprint and a high value end product with a significant life expectancy. Increasingly we are finding that pipelines have been installed with varying diameters or numerous bends or have been poorly rehabilitated with other systems so that only systems like BRAWOLINER 3D can achieve a successful outcome, not only for our pipeline contractor clients but also for their end user clients. Successes like this show just how flexible the BRAWOLINER 3D system can be in difficult circumstances.”