BE-13 Renovation: Lining with Cured-In-Place Pipes - Processes - v01

Static Proof

Flexural Modulus and Flexural Strength

Especially with new or further developed glass fibres lining tubes, an extremely strong increase in the flexural modulus can be observed in order to minimize the wall thickness of the tube.

According to worksheet DWA-A 143-2, the static proofs must always be carried out for two different types of failure. Liners can break, especially if the flexural stress is too high (rupture failure). To minimise the wall thickness, a sufficiently high flexural strength of the liner wall is therefore aimed for on the material side.

For static calculation, however, the second type of failure, buckling, is usually decisive. This is a stability failure, in which the material does not require high strength, but high rigidity in order to minimize the wall thickness. It can be observed that a large number of new lining tube types with ever higher flexural modulus are appearing on the market.

Lining tube Flexural modulus
Flexural strength
UP + polymeric fibres 2.800/1.400
EP + polymeric fibres 2.400/1.200 55/21
UP + glass fibres 10.000/6.500


/ 88