| Renovating branch connections: still watertight after 100 high-pressure jettings |
Joachim Lorch, managing director, Hächler AG Umwelttechnik
Hächler AG Umwelttechnik (environmental technology) is striving to obtain the highest possible certification in Europe and Switzerland for its patented EL 300/600 renovation process used in conjunction with the specially developed injection grout, ERGELIT Kanaltec CF. The test regulations of the DIBT (= German Institute for Engineering) and the QUIK Committee (= quality assurance in the repair and renovation of non-accessible pipework) put heavy emphasis on the quality of the materials used and on the durability of the renovation work.
In this procedure for renovating domestic connections, injecting the ERGELIT grout is controlled from the service vehicle. The operator can regulate the amount of fresh mortar according to the extent of the damage, and thus make a reliable, complete and long-lasting repair of the defective areas and cavities.
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The Hächler EL 300/600 system on test
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Successful laboratory tests by the internationally accredited LPM Test Centre, Beinwil (Switzerland) on lines laid down by the DIBT and the QUIK Committee gave the green light to subsequent practical trials.
Checking ERGELIT Kanaltec CF’s resistance to very high levels of attack was carried out by immersing in a 5% solution of sulphuric acid (with a pH of 0.5), in a 5% solution of caustic soda (pH 13) and in a 5% solution of household bleach containing peroxyde. After 28 days immersion in the liquids described, which never occur in these concentrations in domestic sewage, the changes in the prisms (length, mass, flexural strength, compressive strength) were measured.
Results:
No negative changes could be detected in the properties of the material. Extreme exposure to 5% sulphuric acid (pH 0.5) leads merely to a slight scouring of the surface of the prisms. According to guidelines ATV A115 and the local regulations based on these, one should not reckon on a degree of acidity of less than pH 6.5 in public sewers. Even in stormwater pipework, one should not expect a level of acidity below pH 4.5. At pH 0.5, the level of attack is 10,000 tmes greater than at pH 4.5. Or, in terms of time, the level of attack registered in 28 days at pH 0.5 would take 700 years to occur in the case of normal domestic sewage. |
| Extract from Report A-27391-2, dated 29.07.2004-11-09 |
| Adhesive strength under laboratory conditions |
| Substrate |
Mean value (5 tests) |
Description of break |
| Concrete |
1.6 N/mm2 |
Majority of breaks in concrete/ some also in both the pipework and the mortar |
| Tile (stoneware) |
2.9 N/mm2 |
Break occurred exclusively in the mortar |
| Fibro-cement |
1.1 N/mm2 |
Majority of lesions in the fibro-cement |
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The values noted must always be read in conjunction with the description of the break. For example: if the break occurs mainly in the mortar or the material of the pipe itself, then the bond is stronger than the basic materials.
The values noted bear witness to the outstanding adhesive strength of ERGELIT dry mortar Kanaltec CF, achieving above 2.9 N/mm2. The test series showed clearly once more that adhesive strength is always dependent on the substrate and substrate preparation. It is remarkable that the high level of adhesive strength was not adversely affected by the very wet substrate.
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| Compressive strength and tensile strength under laboratory conditions |
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Mean value (3 tests) |
| Compressive strength |
77.2 N/mm2 |
| Tensile strength |
8.0 N/mm2 |
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| After completion of the laboratory tests, connection repairs were carried out on site and also on a practice test area in Hächler AG’s works under simultaneous supervision by the DIBT, the QUIK Test Committee and the LPM Testing Centre. |
Test set-up with practical installation of concrete pipes
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After completion of the laboratory tests, connection repairs were carried out on site and also on a practice test area in Hächler AG’s works under simultaneous supervision by the DIBT, the QUIK Test Committee and the LPM Testing Centre. |
Taking a sample of reddish ERGELIT Kanaltec CF on site
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Samples were taken in situ, in order to compare these with the results obtained in the laboratory. In the LPM report dated 23.09.04, the following results were given. |
| Compressive strength and Tensile strength measurements made on-site: |
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Mean value |
| Compressive strength |
68.9 N/mm2 |
| Tensile strength |
8.9 N/mm2 |
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After a recommended hardening period of 28 days and the simulation of the high humidity which is always present in sewers, the load-bearing capacity of the repairs and of the material used – ERGELIT Kanaltec CF – was tested.
Both guidelines specify high-pressure jetting tests during which the renovated connections are subjected to 120 bar / 300 litres, in order to verify the repair’s durability under operating conditions. As a rule a pipe is cleaned every 1 to 3 years, so that the number of jettings corresponds to the same number of years’ wear. The different standards lay down 20 jetting procedures (QUIK) or 50 (DIBT). Altogether 100 high-pressure jettings were carried out at identical repair points, including 50 passes using the Hamburg method.
On completion of the jetting test, water-tightness is demonstrated as per the SIA 190.203 standard or DIN EN 160. |
Hamburger high-pressure jetting test with 120 bar/300l/min |
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Using the QUIK model |
Using the DIBT model |
| Parameters: |
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| Jet pressure (measured) |
120 bar |
120 bar |
| Angle of jet |
10° and 30° |
10° and 30° |
| Number of jets fitted |
10 |
10 |
| Number of test passes |
20 |
50 |
| Reverse speed |
0.1 metres per sec |
0.1 metres per sec |
| Forward speed |
0.5 metres per sec |
0.5 metres per sec |
| Amount of water (measured) |
300 litres per min |
300 litres per min |
| Additional grit (Hamburg model) |
Not applicable |
Not applicable |
| Test piece subjected to |
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| 100 tests procedures in all |
50 |
50 |
| Additional grit |
No (but some grit in recycled water?) |
Yes (5 litres ground limestone per jetting) |
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After 20, 50, 80 and 100 passes, an independent firm recorded the results by means of a TV inspection and watertightness tests. This step-by-step testing method was chosen in order to identify at what points in time possible factors affecting the repaired lateral connections occurred.
Test report
Quote from the LPM report of 23.09.04 (after 100 test runs): Slight traces of scouring can be seen on the branch connector, particularly around the mortar collar. The connections are watertight within the norms. Both joints (made with ERGELIT Kanaltec CF) withstood 50 high-pressure jettings as per the QUIK test and another 50 test procedures as per the Hamburg model, without any sign of damage. This corresponds to at least 100 years of normal use.
On completion of the renovation work and subsequent testing within the closed system, the lengths of pipe renovated were excavated in order for the effects of the renovation procedures to be recorded. |
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The excavated test piece, showing repaired cavities |
Excavated: connection renovated with ERGELIT Kanaltec CF, after 100 high-pressure jettings |
The references supplied by engineering firms and local authorities, as well as the evaluation of renovations carried out 5 years previously, confirmed the results of the practical trials performed.
The results and findings of the IKT test “Repair procedures for branch connections” (June 2004) were taken into account during the tests. The Hächler EL 300/600 procedure came out top in the category ‘extreme damage’.
All in all, the characteristics of the Hächler EL 300/600 patented renovation technique, confirmed by the DIBT, QUIK Committee and LPM AG Test Centre experts, and used in conjunction with ERGELIT Kanaltec CF injection grout, go to show how highly suitable this technique is for renovating sewage pipes.
The reports and detailed results of the tests are available from the manufacturer, Hächler AG Umwelttechnik, Swiss (tel. 0041-56-438 05 50 or info@haechlerumwelttechnik.ch) or from HERMES Technologie Ltd. , Hastings, UK office@hermes-technologie.com |
