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Brandenburger Liner GmbH & Co.

Condition of contract:

APS testing guideline

An important on-site test is conducted by the IKT institute for subterranean infrastructure. The leak test is performed as follows: A sample section of about 30 x 20 cm is inspected by an independent expert. The IKT checks the leak tightness of three samples as shown in the images. The red drop consists of local utility water and should have a diameter of about 45 mm. The evaluation is based on the passage of testing liquid through all three sample sections. The two possible results are TIGHT and NOT TIGHT.

Flushing test

In the flushing test, a liner's flushing resistance is tested under defined conditions. Flushing resistance is required because sewers are flushed regularly for cleaning and removal of obstructions. A hose with a flushing nozzle is pulled through the lined pipe. Dirt is flushed from the sewer with high-pressure water. In the past, the "Hamburg model flushing test" was used. In this test, the liner was subjected to 30 flush cycles from a flushing head with eight 2.6 mm nozzles and a water pressure of 120 bar. If the liner was undamaged afterwards, then the test had been passed. Since about 2 years ago, the test is conducted according to DIN 19523. This test can be done in the laboratory. Its principal difference from the Hamburg-model flushing test is that not the pressure but the jet energy density is the critical parameter. The liner is exposed to a jet energy density of 330 W/mm², which corresponds to a pressure of 90 bar at a flow of 280 l/minute. If the liner shows no signs of damage after 60 cycles, then the test has been passed and the liner can be installed. In addition to the Hamburg-model flushing test and the test according to DIN 19523, there are other national tests like the Quik flushing test in Switzerland. In addition to high pressure and numerous flushing cycles, this test also adds gravel to the flushing water to increase the abrasive effect.

Liner flexural strength

If it is too low, then the liner has insufficient load capacity and may break under less than its rated maximum load. This characteristic is measured in a three-point bending test, just like the modulus of elasticity.

Liner installation

A hose carrier soaked with a reactive resin is drawn into the sewer and pressed against the sewer wall through inflation with compressed air. A chemical reaction in the resin turns the hose into a stable, load-bearing inner lining. The technology is completely trenchless and requires no digging whatsoever. The flexible liner hoses are typically applied using existing inspection shafts in the sewer. The special characteristics that set the Brandenburger liner system apart from other pipe lining types are: • Use of seamlessly wound liners made of glass fibre laminate webs
• Unique saturation of the raw materials before the production of the pipe liner with UV-reactive UP resin         (possibly with addition of peroxides for the variation "hybrid curing" for larger wall thicknesses over 10         millimetres)
• Drawing in the liner on a protective foil and form-fitting expansion using compressed air
• Curing of the liner using precisely dosed UV exposure ("BLUETEC® technology").


If exposure to municipal wastewater is a factor, then a group 3 (DIN 18 820 T1) or type 1140 (DIN 16 946 T2) is generally used. For aggressive industrial wastewater, e.g. containing alkaline solutions and/or with high temperatures, the GFRP composite is impregnated with a special vinyl ester resin. This resin corresponds to group 5 in accordance with DIN 18 820 T1 and type 1310 in accordance with DIN 160946 T2. Both resins are compliant with the international standard DIN EN 13121. The polyester resin is categorised as group 4, the vinyl ester resin as group 7a.

Sewer rehabilitation

The term sewer rehabilitation denotes a number of methods for rehabilitating wastewater pipelines. The purpose is to seal pipes against ingress of groundwater and egress of wastewater, to restore structural stability, and/or to stop corrosion. Trenchless sewer rehabilitation, or no-dig methods, describes methods that do not require opening the surface to be opened along length of the sewer. This reduces construction time, cost, and environmental impact. The methods can be used for sewers with nominal widths from DN 100 to DN 5000 (standard diameter in mm). Trenchless sewer rehabilitation accounts for about 50% of the sewer rehabilitation market. Trenchless sewer rehabilitation is divided into three process categories: Repair, renovation, and renewal. The pipe lining method is a renovation process. Renovation methods are used for locally constrained, repetitive, and extensive damage. The process can be used to work a single conduit (sewer section between shafts) or on several adjacent conduits in one go. Processes requiring workers to enter the sewer are used only in larger dimensions (> DN 1000 mm). Pipe lining and relining methods are the best established renovation processes, with a market share of about 30% in trenchless sewer rehabilitation. Again, two basic processes can be distinguished, heat-curing and UV-curing. In the heat-curing process, resin-soaked felt hoses are inverted (rolled) into the sewer using steam or hot water. The chemical curing reaction of the resin is initiated by the heat of the water or steam. In UV processes, glass-fibre hoses are pulled into the sewer and inflated with compressed air. The chemical reaction is initiated by UV light emitted by a robot moving along the length of the liner on the inside. UV-curing processes account for about 55% of the market in pipe lining. Our process is the leading technology for trenchless sewer rehabilitation for diameters from DN 150 to DN 1000. The Brandenburger winding process exceeds all requirements and sets the gold standard for mechanical stability, chemical resistance, and leak tightness. With a share of about 35%, Brandenburger is the market leader for UV-curing processes. However, there is still plenty of room for development.

Young's modulus

Pipe liners are exposed to a variety of loads, e.g. groundwater, road traffic, or the pressure of the earth. They need to be designed accordingly and have sufficient load capacity. The Young's modulus is a key mechanical characteristic in this regard. It is measured by means of a three-point bending test on construction site samples. The measured Young's modulus (or modulus of elasticity), is compared with the specification. In formulas, it is abbreviated as  E . A greater Young's modulus means that the material resists deformation more. A component made of a material with a high Young's modulus (e.g. steel) is therefore rigid; a component made of a material with a low Young's modulus (e.g. rubber) is flexible. What does this mean for our purposes?The glass mats we use are designed to fulfil the load capacity requirements in the cured liner. ADV 75 for instance has a Young's modulus of 7500 N/mm².