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For many years, when smaller drainage and sewer pipelines have required repair due to deterioration and/or leakage, it has been necessary to either remove the old pipe and replace it with new or insert a lining into the existing pipe.
Often in the modern industry this will require a significant amount of equipment and site preparation to ensure that the installation procedure can be undertaken safely and efficiently with minimum disruption to the client or those living and working nearby. With many of the lining systems currently available there is also a need for on-site or near site facilities to impregnate inversion liners or facilities to store impregnated liners whilst the pipelines are prepared. This also applies to many of the sprayed application techniques that require high pressure pumps and mixing systems as well as specially designed spray heads. Whilst such liners can provide a long term solution to the problems of many pipelines the circumstances surrounding the installation can be challenging.
This is now no longer the case with the development of a new resin lining system by Finland-based Picote.
The new resin coating systems utilises a specially formulated two-part resin that is applied to the inside wall of the deteriorated pipe using a specially designed brush system, Picote Coating Pump and the Picote MINI MILLER 8/17 which powers the Picote Coating Brushes.
Designed specifically for Coating drains and sewers from DN32 to DN150 (1¼ in to 6 in) diameter, the coating applied provides a damp-proof, corrosion resistant, wear-resistant and non-corrosive lining. If several coats are applied within the same pipe the resin will build to create a new a seamless structural pipe with a 2 to 4 mm wall thickness (depending on the diameter of the original drain). The estimated service life of the new pipe is between 30 and 50 years. The new low friction inner surface of the lining also permits an increase in the flow inside the pipe thereby minimising the future potential of blockages.
The new lining can be applied to concrete and cast iron pipes from DN32 to DN150 and to PVC pipes from DN70 to DN150 (however, it is not recommended for DN32 to DN50 PVC pipes which is expected to carry very hot water). The resin used for the lining has also been developed so as not to produce harmful gases during mixing and after hardening.
Once hardened the new lining will withstand flow temperatures from -40 to +120°C (with special application this upper temperature can be as high as +200°C).
The lining system has also undergone significant testing in Finland and has been Certified by VTT, Finland: Principle VTT SERT R041 trenchless drain renovation method (Certificate No. VTT-C-8552-12 (2613 Water and Sewer equipment products)). The testing also recommends a minimum wall thickness for the lining of 2 mm and in DN100 or larger pipes this recommendation increases to a minimum wall thickness of 3 mm or more.
The Picote Coating system is unique in that whilst it is applying a resin layer within the deteriorated pipe the resin is not sprayed onto the pipe wall but brushed.
Armed with just a CCTV camera, the Picote Coating Pump, the Picote Mini Miller, the necessary accessories (brushes hoses etc.) and the two-part, the contractor is ready to complete the lining operation.
First the pipeline is cleaned and if necessary degreased and abraded with Picote’s Smart Cutter™, or other suitable cleaning tools, to provide a good rough pipe surface to which the resin can adhere. Then the application hoses and the Picote Coating pump are prepared. It is recommended that the resin delivery hose is no longer than 15 m from the pipe access to the farthest point of application.
With the delivery hoses prepared and connected to the Picote Coating Pump it is then necessary to select the correct brushes to complete the application. This selection depends on the pipe diameter being lined, reference to the manufacturer’s listing is necessary at this point. If the pipe being repaired contains bends it may be necessary to select a pair of brushes that are separated by a flexible link to ensure even coating through the bends.
Once the brush selection has been made these are connected to the head of the Mini Miller shaft. The resin delivery hose is the attached to this shaft just behind the brush assembly. The CCTV camera head is also attached to the assembly just behind the delivery hose to allow the operator to see the coating operation as it progresses. With all in place the resin is then mixed and added to the delivery side of the Picote Coating Pump. The lining run is then ready to commence.
The Mini Miller shaft with the Coating delivery hose and CCTV camera attached is placed into the pipe and the Pump and Miller are started. The Coating Pump delivers the resin to the inside of the pipe and as the Mini Miller shaft rotates this in turn rotates the brushes that spread the resin over the inner pipe wall. The coating operation is started at the end of the pipe farthest from the access point. Resin is pumped into the pipe and brushed on to the wall over lengths of between 200 to 300 mm (8 in to 12 in) at a time. Each length of coating is then checked by pushing the brushes back to starting point and checking the coating with the camera. 
This is repeated over the length of the pipe being lined until the brush assembly reaches the access point. If further coats of resin are required this is normally not applied within 4 hours of the previous coat being completed. Picote recommends various coats depending on the pipe diameter.
It is further recommended that the pipe should not be placed back into service within 24 hours of the final coating being applied.
One advantage that the new system has over many other coating type renovation systems is that is has been designed to be applicable to both horizontal and vertical pipelines. The system offers significant improvements in performance when applying resin in vertical pipes and when passing lateral connections. 
With this operation the only consumables are some lengths of hose because after cleaning all other parts and equipment are reuseable.
Commenting on the new coating system Heikki Jyrämä, production director of Picote’s trenchless services in Finland said: “This new system is designed to be easy to handle, quick to apply and simple to use, enabling it to be utilised by all levels of contractor. The minimal equipment requirement, the simplicity of the resin handling system and the ease of application will mean that several pipes can be lined by one crew in one day, improving productivity for many companies, particularly smaller contactors. Once the basic equipment has been purchased the day to day running cost of this technology is also minimised because the majority of the system is reused time and again.”