An interactive or semi-structural liner relies on the existing pipeline for some measure of radial support to resist all applicable loads without failure over its design life.
This is the most environmentally friendly rehabilitation option available, as it allows for the installation of thin-walled PE 100 liners, reducing material usage, minimising the installation footprint, and increasing flow capacity for the asset owner.
What does this mean in practice?
An interactive liner takes advantage of the remaining structural integrity of the host pipe, allowing engineers to specify a liner that operates below the static pressure rating of the pipeline system. Instead of requiring the liner to withstand the full system pressure independently, the host pipe and liner work together as a hybrid system.
How is this achieved?
By thoroughly assessing the condition of the host pipe, its remaining hoop strength can be used to support the strain in the liner. Most host pipes remain structurally sound but may have small joint gaps or pinholes. Well-established engineering calculations demonstrate that a thin PE 100 liner can span holes and bridge gaps of a given size for its full 100-year design life. As long as the liner has sufficient ring stiffness to support itself against external collapse, it can be selected below the system pressure rating without compromising performance.
Where is this used?
Interactive liners have been used extensively in water injection systems for the oil and gas industry, where high-pressure applications benefit from the good condition of steel host pipes. Die Draw is committed to bringing this established design practice into the water and gas sectors, where many pipelines are in similarly good condition.
Recent projects in Sweden and Norway have successfully installed thin liners of SDR 33 to SDR 51 in medium and large-diameter ductile iron and steel pipelines operating at 10 bar. This demonstrates that thinner liners can be a technically sound and highly efficient solution in the right conditions.
Interactive semi-structural liners represent a proven and well-established approach to pipeline rehabilitation. Die Draw continues to refine and advance this process, ensuring that engineers have the tools and knowledge to optimise liner selection.
If you have any questions or would like to discuss this further, we welcome the conversation.
- See Also: Fully Structural Liners
