Lateral Seals Successfully Complete WRc long-term Infiltration tests
After months of rigorous hydrostatic testing by WRc, Trelleborg epros is pleased to announce that its 45° lateral seal product recently passed the WRc’s long-term infiltration test with flying colours, in accordance with the infiltration limits set under the Sewers for Adoption 6th Edition (based on BS EN 1610) for this type of installation. Testing of the company’s 90° lateral seals is currently underway and this test has currently run through the second month of three without cause for concern. An addendum to the report confirming the success of the 45° lateral seal test, detailing the performance of the 90° product, is expected during Autumn 2008.
Test procedureThe WRc test requires installation of the lateral seals to be made into four independent test rigs where clayware pipes are installed, without damage, in a manner similar to those used on real-life installations in the ground. Two rigs were for the 45° test samples and two were for the 90° tests. The four lateral seals installed were then each to be subjected to some three months exposure to an external hydrostatic water pressure heads of up to 5 m in a cyclic pressure regime designed to imitate a working cycle likely to be encountered by the product in the ground. The leak-tightness of the lateral seals is regularly monitored over the test period.
For the test, Trelleborg epros personnel prepared and installed each of the four test samples and installed them into the testing rigs in exactly the manner they would be installed ‘in anger’ in the field using exactly the same equipment, resins and installation processes, including curing for 3 to 4 hours.
Once cured into place the test rigs are filled with water ensuring that all air is expelled from around the test sample. After one day in this condition the cyclic pressure testing regime was initiated. The daily cyclic pressure regime is shown in the accompanying table.
Start-time
Until
Approximate duration to reach head (minutes)
Head (m)
-
09:00
n/a
1
09:00
09:02
2
2.5
09:55
10:00
5
5
16:00
16.01
1
2.5
17.00
17.01
1
1
The long-term aspect of the test comes form the fact that each month of testing of the samples under the cyclic pressure regime was interspersed by 1 or 2 month ‘breaks’ whereby the test sample was left in situ under ‘damp’ conditions before resuming the pressure testing. This was designed to simulate fluctuations in ground water levels between wet and dry seasons. This meant that the test ran under pressure for 1 month, ‘rested’ for 1 month, pressurised for 1 month, ‘rested’ for 2 months and finally pressurised for the final month. Across the whole time frame, the level of infiltration at the repair sites was monitored.
In all cases, the levels of infiltration monitored either equal to or below that allowed for in Sewers for Adoption 6th Edition (based on BS EN 1610), thereby indicating a successful test for the Trelleborg epros 45° lateral seals.
Commenting on the test results, Ian Ramsay, of Trelleborg epros said: “We have always been confident of the performance achievable by our lateral seals. The results of these tests just reinforce that confidence. From a practical point of view this now means that contractors utilising the Trelleborg epros lateral seals can be certain that, once in the ground, they will give not only an immediate solution to infiltration problems at lateral joints but also the long term performance required of them by their water company/authority clients.”
