Questions & Answers

Frequently asked Questions

Below you will find answers to frequently asked questions. If you cannot find an answer to your question, please contact your personal contact person. 


1. Products

Our KERA.Base pipes are designed for standard situations, while KERA.Pro pipes are used for special installation cases, such as with higher loads.

Yes, there is a fitting that enables a change from normal load to high load. This additional joint piece is available in nominal sizes DN 200 and DN 250. The socket is designed for high load and the spigot for normal load.

Yes, there are clay pipes for all common jacking methods. KERA.Drive pipes are available in nominal sizes DN 150 to 600 with an overall length of 100 or 200 cm. Click here for an overview.

Our manholes are resistant to biogenic sulphuric acid corrosion. They are resistant to high-pressure cleaning and have a service life of more than 100 years. They also offer all the advantages that our range of pipes and fittings also offers. For planning and ordering, you can use our manhole calculator in the Infopool. Further information can be found in the KERA brochure.

With our DURA range, we offer an all-round renovation solution for accessible sewer systems. We manufacture tailor-made solutions for full and partial renovation of manholes and sewers. Please get in touch with your contact person for detailed planning.

Vitrified clay pipes are standardized in EN 295, Parts 1 to 7. In addition, the products are manufactured and monitored according to the ZP WN 295 certification program, which contains considerably higher requirements in all particulars than EN 295.

For complex, exceptional situations when laying new sewers or replacing existing ones, we offer tailor-made solutions: fittings, connecting pipes with or without sockets, eccentric junctions, or nominal diameter transitions to cope with any connection situation. When recovering an old, intact section of a sewer, for example, a transition piece to a nominal diameter in our current range can be manufactured. Please get in touch with our contact persons for your specific request.

Transition pieces are available for the following nominal sizes: 

  • DN 100 - DN 125
  • DN 125 - DN 150
  • DN 150 - DN 200
  • DN 180 - DN 200*
  • DN 200 - DN 250

*in Switzerland

The so-called socket base ring is a compensating ring for uniform pressure transmission in socket pipes.

Product drawings can be found in our Infopool.


The choice of connecting element depends on the pipe diameter and the pipe material used. Further information can be found in our KERA brochure on page 95.

The S joint is a further development of the K joint. The S joint is compatible with all conventional vitrified clay pipes and fittings of the same nominal diameter, load-bearing class and with the connection system C. The S joint is compatible with all conventional vitrified clay pipes and fittings of the same nominal diameter and load-bearing class. Vitrified clay pipes with S joint can be combined with fittings and pipes that use K joint. In addition, all tightness requirements according to EN 1610 and DWA A 139 are fulfilled.


Our vitrified clay pipes consist of the natural raw materials clay, fireclay and water. We mine the clay for our products in local regions, which enables environmentally friendly raw material extraction and subsequent ecological restoration. Ceramic products are 100% recyclable and return to the production cycle as fireclay.

The service life of our products is 100 years or more.

Yes. Vitrified clay is abrasion-resistant.

The minimum depth of cover depends on the stress load. In the case of traffic load from road traffic, the minimum depth of cover is 0.5 m. The minimum depth of cover is 1.5 m for rail loads and 1.0 m for aircraft loads. You can determine the exact value with our statics calculator in the Infopool.

The chemical resistance is specified by the EN 295 vitrified clay standard. The resistance is in the pH range from 0 to 14.

The resistance is tested depending on the particular application. You can find further information on our Infopool under Properties > Material properties > Chemical resistance. 


Vitrified clay pipes are certified according to the EN 295, 1-7 and ZP WN 295 standards.

The certifications can be found on our website under "Certification".

Our vitrified clay pipes can be installed under railway lines. Railways approval is listed in the Building Regulation Lists of "Deutsche Bahn" published by the Deutsches Institut für Bautechnik.



2. Planning

In our Infopool you have access to the following calculation tools:

  • statics
  • hydraulics
  • couplings
  • manholes
  • buoyancy
  • connecting sockets
  • profitability

You will also find here all of the CAD drawings for our range.

You can find our online calculators in our Infopool. To access this, please register. Registration is free of charge.


You can calculate statics quickly and easily using the statics calculator available in our Infopool.

There is no set of rules governing how the concrete casing is calculated. The structural design conditions must be used as a basis.


Taking into account the long service life with low maintenance and repair costs, our pipes represent the cost-effective safeguarding of capital assets. With their service life of more than 100 years, they conserve resources and minimize the financial burden of renovation and repair. The economic efficiency of our pipes can be determined with our profitability tool.



3. Sustainability

Our vitrified clay pipes consist exclusively of regionally mined, natural raw materials. They do not release any harmful substances into the environment, have a long useful and are 100% recyclable. They are produced partly with recycled material. Also, green electricity and regenerative energies are used in production. In this way, we have created added value, and this has been confirmed by our Cradle-to-Cradle® certification.

Taking into account the long service life with low maintenance and repair costs, our pipes represent the cost-effective safeguarding of capital assets. With their service life of more than 100 years, they conserve resources and minimize the financial burden of renovation and repair.

Because of the materials used in their production, they are 100% recyclable.