Test methods

General Site Supervision Authorisation

Deutsches Institut für Bautechnik (DIBt), Berlin


The General Site Supervision Authorisation was issued by the DIBt Deutsches Institut für Bautechnik, Berlin for the SAERTEX-LINER® method back in September 2002 (Approval No. Z-42.3-350).

The General Site Supervision Authorisation proves the usability and practicality of the approved item for the purpose of the State Building Laws. The issue of this approval is preceded by intensive tests during the production process and the practical execution on the building site as well as long-term tests by qualified DIBts employees.
The approval is only issued if the manufacturer of the building product can prove the perfect function, environmental compatibility and safety of the method. The General Site Supervision Authorisation is valid for a period of
5 years and then has to be renewed.

Compliance with the terms of the General Site Supervision Authorisation must be proven through regular external controls by a certifying authority approved by the DIBt. External monitoring for the SAERTEX-LINER® is carried out by Siebert + Knipschild GmbH Ingenieurbüro für Kunststofftechnik, Oststeinbek.

If the results of the external monitoring confirm compliance with the terms of the General Site Supervision Authorisation a certificate of confirmation is issued for a further year as proof. The manufacturer is then entitled to identify the building product with the Ü-symbol in accordance with the compliance symbol ordinance.

20,000 h long-term ring stiffness test

IKT Institut für Unterirdische Infrastruktur, Gelsenkirchen

The long-term ring stiffness test records the modulus of elasticity of a liner over a period of 10,000 h or 20,000 h and the extrapolation of the deformation measured according to DIN EN 705 is extrapolated for a period of 50 years (after 10,000 h) or 70 years (after 20,000 h). The test with the SAERTEX-S-LINER® was carried out on real building site samples from the long-term study in Dortmund over 20,000 h (= 2.2 years) between 12 May 2004 and 25 August 2006.

The standard test is carried out for a period of 10,000 h, after which the characteristics can be extrapolated for a useful life of 50 years. The 20,000 h test carried out with SAERTEX-LINER® is unique to date and allows statements on the useful life of the liner for 70 years.

The test also confirmed the excellent characteristics of the SAERTEX-S-LINERS® for a useful life of 70 years with a mean long-term modulus of elasticity of 11,449 N/mm² und a reduction factor of 1.36. These figures correspond to those for 50 years.

High pressure flushing test according to the Hamburg model

IKT Institut für Unterirdische Infrastruktur, Gelsenkirchen

Hamburger Spülversuch According to the Hamburg model, the long-term behaviour of liners, including the opened connections, is tested against high pressure cleaning in a section of pipe at least 20 m long. The aim is to prove that the liner visually resists the loads common in today´s sewer cleaning without suffering any damage. A total of 30 rinsing cycles corresponding to a useful life of 30 years with annual cleaning are carried out and three points are subjected to a three minute permanent load by keeping the nozzle pointed at these points.

Before each cleaning cycle, consisting of the insertion and removal of the rinsing nozzle with a test pressure of 120 bar, 5 litres of a limestone fine flint mixture is filled in at the end of a reach of sewer. This simulates loads that are similar to those that occur on the liner in normal use and with the side branches open. No damage that could affect the functional reliability of the liner may occur during the test.

The SAERTEX-LINER® passed the test in January 2008 as the only liner to date to withstand 70 rinsing cycles.

Abrasion test using the Darmstadt tilting trough


Abrasion test according to DIN EN 295-3 (Darmstadt tilting trough) by engineering consultants for plastics technology Siebert + Knipschild GmbH, Oststeinbek


The abrasion test for liners according to DIN EN 295-3 (Darmstadt tilting trough, minimum of  100.000 load cycles) is carried out in order to check whether the CIPP hose liner withstands to abrasion in a sewer. Abrasion is caused by the usual transport of water and solids in the sewer pipe, basically in the pipe bottom.

As specified by DIN EN 295, Part 3, the ends of a (1.000 +/- 10) mm long pipe section are closed by face sealing plates and the pipe is filled with a mixture of sand, gravel and water. The pipe section is tilted in the test jig in alternating axial directions by 22,5° so that the movement of the test material would cause abrasion on the inner pipe surface. According to the test specifications the test material was natural, uncrushed, round quartz gravel with grain size characteristics.

The test material of 5,0 kg according to DIN EN 295-3, Table 3, is filled into the pipe and water is added until a level of (38 +/- 2) mm is reached. In order to determine the surface abrasion of the SAERTEX-LINER® the test was conducted with 300.000 load cycles. Every 100.000 load cycles the abrasion depth was determined. The tilting cycle was set to a frequency of about 20 load cycles per minute.


This method is also named in the guidelines of the German Institute of Construction Engineering (DIBt), Berlin for the selection and use of inner liners with plastic parts for mixed and sewage water sewers. The SAERTEX-LINER® meet the requirements on abrasion resistance according to the DIBt; with an abrasion depth of only 0,03 mm after 100.000 cycle loads actually an excellent abrasion resistance has been demonstrated. 



Saerbeck, December 2019


An exciting year is almost drawing to a close and our industry has once again seen a lot of progress. 


Saerbeck, December 2019


New Managing Director at SAERTEX multiCom: Since autumn Kai Diecks appointed new Managing Director at German quality manufacturer for GRP liners.


Saerbeck, November 2019


The year 2019 is slowly coming to an end – already today we would like to thank you for a trusting and successful cooperation in 2019! In order to start the year 2020 together with you successfully and well recovered, we would like to inform you about our upcoming inventory and the company holidays at our plant in Saerbeck:


Saerbeck, October 2019


At the "International NO-DIG Conference Florence" in early October, our potable water liner, the SAERTEX-LINER® H2O, was honoured with the "New Technology Award" from the International Society for Trenchless Technology (ISTT).


Saerbeck, June 2019


Do you already know our new app for the 8th Saerbeck Pipe Symposium? Here you will find all information about the event in September in Münsterland. Whether programme, exhibitor, side programme or registration: Everything online and always up to date!


Read all news items here