Tests for sewer rehabilitation

Quality is not only about trust in the companies that do the building work. For sewer rehabilitation it is necessary to present the proof of quality in cold print – for purposes of durability, safety and waterbody protection. We are an independent accredited test institute and document the success of your rehabilitation project on the basis of the test results.

Materials testing

Three-point bending test

This test has been defined as the standard to identify the bending properties. Important notes for sampling are described in the download area.

Vertical crushing strength test

This test is used to determine the initial ring stiffness. This test is done for CIPP as well as for CRP pipes.

Tightness test

This test helps make sure that the laminate features tightness against infiltration and exfiltration. This standard test is done in combination with the three-point bending test.

Cyclical pressure tube test

Simulation of alternating pressure loads  (2 Hertz) from -0,9 to 10 bar for pressure tubes used in waste water or drinking water (up to DN 500, 10⁷ cycles). No bursting test.

Gas chromatography

The residual styrene content allows us to make a statement on the degree of curing of reactive resins containing styrene. We determine the residual styrene content by gas chromatography.

DSC analysis

DSC analysis is used to determine the degree of curing of epoxy resin systems and to compare it with a reference value. The method is used where it is impossible to obtain pipe rings or ring segments, e. g. when branch connections are rehabilitated.

Spectral analysis

Reference spectrums are compared to check whether the delivered resin quality is actually the quality that has been ordered. Siebert + Knipschild has its own data base with reference spectrums of the reactive resins used in all common rehabilitation systems.

Filler and glass content

We use the calcination method to determine the textile glass and mineral filler content of glass-fibre reinforced plastic materials.

DMA analysis

For samples from CIPPs ≤ DN 200 we use this test method to determine the bending Young's modulus.

24-h creep tendency

The creep behaviour is determined by a long-term vertical crushing strength test under a three-point bending load.

Tension Test

Even under influence of temperature (-30°C to 180°C), e. g. for curing reactions of synthetic fibres


Vertical crushing strength test: This test is used to determine the initial ring stiffness. This test is done for CIPP as well as for CRP pipes. Requirements: There are numerous further tests for the quality assurance of sewer rehabilitation projects. In principle our materials tests follow the requirements

• of DIN EN ISO 11296, Part 4;
• of the applicable DIBt approvals;
• of the according rules, such as DWA-A 143-3 (formerly ZTV)


of the German Association for Water Management, Sewage and Waste (DWA).  All tests are conducted in line with the order. All tests are sued to check whether the delivered quality is actually the quality that has been ordered. What are your questions on the requirements, on test conduction or on sampling? We will gladly answer them. Contact