40 years Piping system


A brilliant idea


Gerhard Rosenberg developed the first weldable piping system made of polypropylene 40 years ago


40 years ago Gerhard Rosenberg revolutionised the piping market and at the same time laid the foundation for the entrepreneurial success of aquatherm: In 1981 he developed the world’s first weldable piping system made of the plastic polypropylene and made “fusiotherm” a great success in a short time. In his own words, Gerhard Rosenberg tells of the not so easy path to the new system:

“For some time now, I’ve been quietly considering an entirely new piping system. During our trips abroad we saw that not everywhere had such a well-developed drinking water network as in Germany. In the Jordan bathrooms, the walls were covered to hide the steel pipes that led directly to the roof. There were huge water tanks, which were regularly refilled. If a tank ran empty, oxygen got into the pipes, which in combination with the water led to corrosion. The steel pipes began to rust, the pipes became holey, water ran behind the extensive cladding. In short, the water quality was getting worse and worse.

During my visits to Jordan, I realized that we needed to address the problem with plastic pipes in the sanitation area. However, it is a long way from an idea to its realization – I had learned this from my earlier inventions. We already had experience with pipe production, but for such a system we also needed the right fittings as well as a connection technique that would be easy and quick to handle on the construction site.

A great help in the development of the plastic pipe was the company Hüls, especially the engineer Helmut Klawitter, who is now responsible for us. He visited us frequently. We often stood together in the lab and consulted at length. In the meantime, tests on our new heating pipe showed that it also met the standards for drinking water. The pipes were connected with compression fittings that withstood a maximum pressure of three bar, which is common in heating systems. In the sanitary area, however, a pressure of up to ten bar is required. In addition, larger pipe dimensions are required because the water has to run quickly into the washbasin, bathtub and toilet bowl – often even at the same time.

Idea: Make connections yourself

I finally had the brilliant idea: Why don’t we make the connections between the pipes ourselves, i.e. sockets, T-pieces and elbows? Tools for this did not exist on the market until now, so we had to develop them as well.

In long discussions with our plant manager Dieter Tusche and other employees, the idea for a new type of joining technology grew and grew. We made plans for the development and production of new parts, tools and machines. I also asked Helmut Klawitter for advice on which company could support us. He thought about it for a moment and said: “There is the Gruber company in Austria, which produced fittings made of polybutene some time ago. However, nothing ever came of it. But the tools should still exist. I know the boss, I’ll give him a call.” We got an appointment at short notice, visited the company and ordered moulded parts and fittings for about fifty thousand marks. Mr. Gruber smiled at this, apparently he did not take our small company seriously. This was also reflected in the fact that the deliveries were extremely slow in arriving at our premises: In January the sockets, in April the angles and in June finally the T-pieces. It couldn’t work like that. I went in search of a company in our region that could design and manufacture tools. I found one in Finnentrop-Weringhausen. I discovered the company Erwes-Reifenberg, which had specialised in precision mould making. They were already active in the field of injection moulds. We quickly came to an agreement and I had the first molds built. Now we needed a plastic moulding producer. I found one in Lennestadt-Grevenbrück: the company FM-Plast was prepared to work with us.

Welding unit developed together with LEWA

We finally had an elaborate system of pipes and fittings, but they still needed to be put together. A welding machine was required. The temperatures for material processing and the type of connection technology were known to us, so that we were able to develop the suitable device together with the training workshop Attendorn (LEWA). In the process used, the pipe and fitting are pushed simultaneously onto a heating mandrel and socket at a temperature of about two hundred and sixty degrees. After a few seconds of heating, the two elements can be detached from the device and joined together. A few minutes after cooling, the line can already be loaded. This fusion welding technique gave our pipe system its meaningful name: fusiotherm (now aquatherm green pipe).”

Contact: aquatherm GmbH | Biggen 5 | 57439 Attendorn | Germany | Tel: +49 2722 950 0 |

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