DIBt Certification for the Easy Pur "Spot Repair" partial lining system

Sep 20, 2006

Partial lining has established itself over many years for the isolated repair of inaccessible waste water pipes as an economical and technically mature alternative solution to traditional "dig-out" repairs.

As of March 2006, the partial lining "Spot Repair System" from I.S.T. GmbH in Bochum, Germany has been granted General Technical Approval from the German Institute of Construction Technology (i.e. DIBt). License number Z-42.3-388 certifies approval of the system for the rehabilitation of buried, damaged waste water pipes in pipes ranging from 100 to 500 millimetres in diameter.
Due to its versatility and practicality, the "Spot Repair System" works according to the individual wishes of the contracting company and its employees.
As opposed to the properties of typical summer and winter resins offered by other manufacturers, the "Spot Repair System" enables a uniquely flexible partial lining procedure employing a three-component silicate isocyanate resin system called Easy Pur. The three components consist of resin, curing agent and a catalyst which influences the reaction time of each mixture.
As a result, all relevant parameters can be compensated for, in particular the surrounding conditions, pipe dimensions and distance from the manhole to the damaged spot. The system even allows for the possibility to remove a packer within thirty minutes! On the other hand, a setting time as long as sixty minutes can be accommodated. The physical and chemical properties, impregnation procedure, adhesive qualities and smooth, homogeneous surface of the cured liner clearly exceed the products currently on offer by the competition.
In its packaging options, as well, I.S.T. GmbH offers cost-effective alternatives to their standard Easy Pur canister bundles in the form of combination cans and tubular resin bags. These are appreciated by customers who carry out partial liner installations less frequently. A two-component (resin and curing agent/catalyst) variety of Easy Pur named Easy Pur 2k is used in the small quantities filling the cans and bags, but also available in 70-kg canister bundles. The tubular resin bag/pouch is available in four different sizes with the two components separated by a seal. Once the seal is broken, the components can be mixed by hand inside the pouch and the mixed resin poured from an opening cut from the bag.
When it comes to glassfibre matting, I.S.T. corresponds with the best available technology, naturally, offering corrosion-resistant Advantex glassfibre. Consisting of ECR-quality fibreglass fabric and non-woven fibre matting sewn together, it is available in a variety of weights and widths.
In order to achieve successful and durable repairs, it is vital to strictly comply with the installation instructions from the manufacturer. Explicit attention should be paid to the necessary conditions regarding preparation of the substrate for successful installation of a partial liner. Smooth and/or slippery pipes (e.g. glazed ceramic liner), in particular, should be chafed beforehand in addition to the usual high pressure water spray cleaning so as to effect a more solid and lasting bond to the pipe wall.
During the lamination process, the glassfibre matting should be folded so as to expose the dull (i.e. non-glossy), non-woven fibre surface to the wall of the old pipe (including the overlapping edge) as well as to the inside of the pipe.
In addition, it is important to ensure that the width of the installed liner is at least 3 millimetres. To realize this, the finished liner should consist of anywhere from two to four layers depending on the variety of glassfibre matting used.
Partial liners adhere more strongly to the old pipe as sectional tube liner does. With a sufficient thickness of glassfibre matting together with the manufacturer-recommended quantity of reaction resin, the pressing of a partial liner (1 to 2 bar depending on the job conditions) against the old pipe by a mobile packer causes "surplus resin" to permeate into cracks as well as the crevices in sleeves (see Figure 3). Beyond the primary bond, this augments the grip of the liner to the old pipe and/or damaged spot.
Furthermore, a wedge of miniscule thickness is developed at the edges of the liner (see Figure 4) that offers the foreign bodies and sands common to waste water no gap by which to attach to the liner. This characteristic effectively prevents such stresses from causing mid- to long-term stripping away of the liner.
It cannot be emphasized enough how the success of each and every partial lining installation is absolutely dependent, beyond use of the highest quality products, upon the knowledge and precision of the participating technicians and their adherence to the manufacturer instructions.
It is for this reason that I.S.T. GmbH regularly offers practical training at its headquarters for professional installation contractors and their job site personnel. The training courses include a theoretical component which compliments, and provides a basis for, the practical aspects. The completion of each course is acknowledged by certification for all participants.
Lastly, authorities responsible for tenders should ensure that substrates are adequately prepared and contracts taken on by qualified professional service companies using proper equipment. This should be addressed in the tender documentation and furthermore upon award of the contract. In this way alone is it possible to utilize excellent equipment successfully to effect the flexible and cost-effective installation of partial liners.


Patrick McKelvy

44795 Bochum


+49 (234) 51 69 96-0


+49 (234) 51 69 96-6




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