Elated about the high number of awardees in 2020: Lab manager Mirjam Lutzke and Managing Director Andreas Haacker, Siebert + KnipschildThe seal was introduced by Siebert + Knipschild in 2015 to provide clients with an overview of the quality of contractors in Germany. Behind this is the realization that an assessment of CIPP quality cannot be made solely on the basis of the products. “The CIPP liners supplied from the factory have proven their quality via their approval. However, they are preliminary products that only acquire their final technical and chemical properties through a procedural curing process on site,” says Andreas Haacker, Managing Director of Siebert + Knipschild.

Quality control promises long-lasting results

In contrast to factory-produced pipes, for example, CIPP liners do not acquire their final geometric and mechanical properties until they are cured on the construction site. In this context, the entire process – from quality assurance to the technical qualifications of the employees to the preparation of the construction site – is crucial for the result. “The more a company deals with a system, the more confidently it can deal with imponderables,” says Haacker, explaining the fact that the seal is only ever issued for one specific system at a time.

According to Haacker, the number of awardees has never been as high as this year. The need for companies to meet a high standard of quality is strong, according to Haacker. “Overall, we continue to see a clear effort in CIPP lining not only to meet requirements, but also to give clients peace of mind: they are getting a long-lasting product for generations to come.” The depreciation period for CIPP liners is often around 50 years, he says, and the expected practical lifespan goes well beyond that.

Deficiencies can have several causes

The seal statistics include samples from CIPP liner construction sites of contractors that were submitted to Siebert + Knipschild over a calendar year. At least 95 percent must meet the requirements of the approval. Haacker: “Achieving this value is a very good achievement. Already in the approval, the probability of a failure rate is statistically taken into account via a quantile value calculation.”  If systematic errors are detected via the seal statistics, the engineers often get to the bottom of the matter together with the parties involved.

One of the sources of error, he said, is inadequately prepared dewatering. “Water is an inhibitor for the curing reaction in most resins applied in the main channel. You can then see that at a glance and smell it for a long time,” Haacker explains. An insufficiently cured liner becomes noticeable through a lasting styrene odor, because the solvent only polymerizes – i.e. chemically binds – through successful curing.

Another shortcoming, according to Haacker, is incorrect dimensioning of the nominal diameters, which leads to the actual base layer not reaching its wall thickness due to resin displacement.

“By now, most contractors have realized that mistakes can have very unpleasant consequences. But network operators also take care to ensure that their projects are a success – and not just in economic terms,” concludes the expert.

Siebert + Knipschild provides insights on quality – also on demand

According to Haacker, the seal is a good reference for successful projects – for both clients and contractors. To qualify, at least 20 test specimens of a system must have been submitted in the previous calendar year. Wall thickness, E-modulus, flexural strength and watertightness are considered. The test takes into account components submitted both by the company carrying out the work and by the client of the individual projects. In addition, they must come from at least four different construction projects.

Overall, it is clear that the seal is a good opportunity for clients to identify which companies deliver good quality. At the same time, the seal helps contractors score points on the market for consistently high-quality services. But there is another added value that is now appreciated by contractors:  Those who commission the seal receive certified statistics for a current year with the seal certificate. “Increasingly, companies are using the data over the course of the year to manage internal quality assurance. We provide this data on demand,” says Haacker.

Firmen können Antrag auf der Website stellen

Bereits jetzt laufen bei Siebert + Knipschild die Vorbereitungen für die Siegelvergabe 2021. Wer das Siegel beantragen möchte, findet hier das Antragsformular sowie eine detaillierte Auflistung der zu erfüllenden Kriterien. Da in die Wertung auch Projekte einfließen, bei denen nicht das ausführende Unternehmen, sondern zum Beispiel der Netzbetreiber die Prüfung veranlasst hat, ist eine entsprechende Einverständniserklärung erforderlich. Dafür steht eine Vorlage zum Download zur Verfügung.

Overview of seal holders 2020