|iMPREGLiner passes "Stuttgarter Stresstest"
"Stresstest" shows excellent practical results and attests best material data for the iMPREGLiner over its whole service life.
Today, the performances achieved in many projects, decisions and testing methods are being probed by stress tests – the latest media buzzword.
The Badische Zeitung, for instance, wrote on 9 July 2011: "Anything that has not yet been politically nailed down is put to a stress test – be it the Stuttgart 21 railway project, nuclear power plants, banks, insurances, power networks or – in the figurative sense – Westerwelle´s Libya policy and the women´s national football team."
The demands being made on the quality of restoration methods continue to increase and so there is also a need for enhanced tests and a broader scrutiny of the behaviour of these methods over the long-term.
Generally, sewer restoration using hose-liner systems today requires approval from the Deutsche Institut für Bautechnik (DIBt – German Institute for Construction Technology). Such approval is based on various individual tests that are carried out independently of each other. These include a long-term test in which the material is stressed for 10,000 hours to determine its quality as well as comparisons and assessments of the results from construction-site samples being made on the basis of values kept at DIBT.
All individual tests have been developed and continuously improved over years. The methods used to test mechanical values and behaviour when the material is exposed to pressure washing and abrasion throughout its life are useful in the qualification of its properties.
In response to current discussions concerning the actual lifetimes of installed hose liners, iMPREG has broadened its search to find a testing method that delivers more reliable information about the lifetimes of installed hose liners.
Currently, new samples are used for each separate test carried out to assess material properties. Which means that the results from the separate tests do not take any account of the effects produced by other testing methods. But the section on which restoration work has been carried out and which is the subject of the test is at the same time also exposed to the effects of abrasion and pressure washing. And as these effects also influence lifetimes, it is only natural to combine the two individual testing methods and assess the results using the same samples. The characteristic mechanical values determined after the combined test should provide more reliable data about the material.
The actual execution of these tests were naturally coordinated with such leading testing institutes as Siebert und Knippschild and IKT and both thought that the new combined method would be useful and expressive.
The test was divided into three parts:
- Examination of abrasion behaviour in accordance with DIN EN 295-3 (Darmstädter Kippe – Darmstadt Abrasion Test)
- Resistance to pressure washing in accordance with DIN 19523
- Pressure washing test in accordance with DIN 19523 Section 3.3
The test was carried out with the iMPREG Liner GL01 DN300/4mm.
In order to simulate 50 years of use in sewers, a half shell was exposed to 100,000 changing load cycles using the Darmstadt Abrasion Test in accordance with DIN EN 295-3.
(Report No. 11.37739 by Siebert und Knippschild.)
The next step saw the half shell being submitted to a material test in accordance with DIN 19523 at IRO. The half shell was then exposed to a jet of high-pressure water that was directed at it from a specific angle. (Report No: G30709 IRO)
The half shell already stressed in the Darmstadt Abrasion Test and by pressure washing was inserted in a new fibre glass reinforced pipe at iMPREG´s testing facility. The half shell was glued with epoxy resin into the pipe to enable a practical pressure test to be carried out with maximum washing pressure. The relevant parameters (washing pressure, throughput, water jet power density) were set at considerably higher values than those conventionally used in such tests with the aim of also simulating extreme cleaning conditions. The maximum possible power that a washer vehicle is capable of, i.e. 175 bars, was used. A washing pressure of 100 bars was still measured at the washing nozzle.
(Expert Report No. 11-510-17800-SB; Siebert und Knippschild.)
Samples of the material exposed to this marathon of tests were taken and examined in accordance with DIN EN ISO 178 (in conjunction with DIN EN 13566-4) to determine their characteristic mechanical values and water permeability based on DIN EN 1610.
In summary it may be stated that the initial visual examination showed that iMPREG Liner GL01 had suffered no apparent damage besides that already caused during the preliminary examinations. The water-tightness of the laminate and the mechanical strength properties of a sample taken from a tested fibre glass reinforced hose liner did not deviate from the approval-relevant values. (Test Report No. 11.38720; Siebert und Knippschild.)
Although the results achieved with this extreme test are outstanding, the concluding sentence in the test report is rather matter-of-fact:
In regard to iMPREG GmbH´s hose liner with Approval No. Z-42.3-365, it may be confirmed that it is durable over a period of at least 50 years when exposed to increased simultaneous stresses resulting from pressure washing and abrasion.
The expert accompanying the tests was more subjective in his choice of words: "This material appears to be indestructible."
The aim of the examinations was not to broaden the scope of current testing methods but rather to submit the material to a targeted practical test with the purpose of increasing confidence in the product. We have achieved this goal with this unique test.
The detailed test reports and certificates may, of course, be downloaded from iMPREG´s Internet site. Please don´t hesitate to contact iMPREG GmbH in the event of any questions regarding the tests and results.
Prokurist / Technischer Leiter