Brawoliner Passes Infiltration Test
In mid-February 2006, Thames Water plc, one of the United Kingdom’s main water companies, and Karl Otto Braun (KOB), along with its U.K. renovation technology consultant CJ Kelly Associates Ltd., undertook a strictly controlled test to establish Brawoliner’s capacity to handle installation conditions including significant infiltration.
The test, while being promoted by Thames Water, has been designed, in conjunction with most U.K. water companies, to establish the relative performance of different lining systems in resisting:
• The admittance of infiltration either through the liner wall or along any annular space between the liner and the host pipe
• The structural loads on the liner at unopened connections
• Groundwater or other pressures in laterals during installation
• Environmental damage to soil and groundwater
The test, which is currently on the path to becoming a U.K water industry standard, is limited to those systems where a permanent tight fit is anticipated between the liner and the host pipe, including those where resin may be exuded into any available spaces.
Systems that rely on chemical bonding to the host pipe wall or hydrophilic seals are deemed to require additional long-term testing, including cyclic loading and alternate wetting and drying cycles in fluids mimicking sewage.
One important factor of the test is that it requires any installed liner to have at least the same leak tightness level as that of a new pipe.
For the Brawoliner test, a rig using a 200-mm diameter pipe was used to imitate a buried pipeline, subject to a 5-m head of water pressure to give significant infiltration at the joints and from the branch. The test rig incorporated wide gaps at two pipe joints and narrow gaps at two other pipe joints to be a maximum of 3 mm wide. A T branch with a 45-degree angle was included in the test rig, positioned with the entry to the main pipe being 45 degrees above the centerline of the main pipe.
The test allows assessment of the effectiveness of linings at resisting infiltration that arises at the joints and the effectiveness in prevention of the migration of infiltration, along any space between the lining and the pipe that may arise through fractures or permeability of the host pipe.
A series of ferrules and seals were used to ensure the 5-m head of water test pressure could be applied at the joints and T section as required. For the Brawoliner test, the liner was installed under wet conditions.
The day after the liner was installed, the main testing procedure began. Water pressure was applied across the test rig and measurements taken over time.
With the external test pressure applied at all joints and the branch for 30 minutes, the test showed zero end leakage from the ends of the test rig or through the lining, indicating zero infiltration at any point along the rig.
Individual tests were then run between the ferrules at joint and branch locations to check for any annular leakage between ferrule points. Again, at each individual test location there was zero leakage and therefore zero/no infiltration was found.
The Brawoliner infiltration test was a complete success. The test was observed by independent witnesses for the test rig construction, the liner installation operation and the test itself.
Commenting on the Brawoliner test, Don Ridgers, Thames Water plc., said: “Groundwater infiltration into sewers can be a significant problem to the water industry, both in the United Kingdom and elsewhere. And the sewerage undertakers have been trying to find lasting solutions by the development of a common test method.
“The product testing that has been taking place over the last two years has exposed just how poorly some of the available lining systems perform with respect to leak tightness. Brawoliner is only the second product to pass the test without supplementary seals.”