Performance of a cured-in-place pressure pipe liner passing through a pipe section without structural integrity

• We determine that the unconfined hoop stress governs at operational pressures.
• Friction has essentially no impact on this particular limit state.
• Hoop stiffness must be greater than axial stiffness to minimize tensile stress.
• Uniaxial material properties dominate at critical locations in the liner.
• Maximum stress criterion is used to estimate burst pressure.

The performance of a cured-in-place pipe (CIPP) liner as it spans a section of host pipe that has lost its structural integrity is examined through finite element analyses. Orthotropic and nonlinear analyses are used to examine 3D effects. The 3D analysis is compared to an earlier axisymmetric model. The effects of friction between the liner and the old pipe as well as the orthotropic material properties of the liner are investigated. Failure pressures and unconfined hoop displacements are calculated using failure criteria from ASTM F2207-06 and it is concluded that the liner response is dominated by uniaxial rather than multiaxial strength properties. Lastly, it is recommended that the maximum stress criterion be used over the interactive stress criterion for this loading condition.

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