How It Works

How it Works

Step 1: Pipe System Diagnosis

The project begins with mapping the internal plumbing system and a camera inspection of drain and sewer lines is performed. A plan is then implemented to minimize disruption and afford the most efficient timeline for work completion. Our technicians will inspect the pipe for integrity and spot repairs will be made to excessively worn joints and fittings if required.

Step 2: Preparation and Cleaning

The next step involves removing roots and calcite in order to return the pipe to its original functioning diameter. Cast pipes may require additional preparation if there is significant corrosion or missing sections of pipe. Removal methods may include jetting the lines, or using various pneumatic tools.

Step 3: Structural Installation

Nu Flow’s patented trenchless lining system involves double-entry access to pull an epoxy-saturated felt liner with an internal bladder inside the host pipe. The bladder is then inflated in place and later removed, leaving in place a smooth jointless new pipe within the host pipe. Our lining method allows us the ability to line multiple 45⁰ or 90⁰ angles as well as the option of lining specific sections of pipe without lining the entire length. If access is only available to one side we are able to push our liner into place as well.

Step 4: System Reassembly and Final Inspection



The main alternative to traditional sewer replacement involving trenching is cured-in-place lining, sometimes referred to as ‘soft lining’ or ‘cured-in-place-pipe’ (CIPP), which has dominated the non-man-entry sewer renovation market in many countries for over twenty years. For brevity, these Guidelines refer to all cured-in-place lining techniques as CIPP systems, although it should be noted that not all providers of such systems use this term.

Although several competitive systems are now available, the common feature is the use of a fabric tube impregnated with polyester or epoxy resin. The tube is inserted into the existing pipeline and inflated against the pipe wall, then cured either at ambient temperature or by re-circulating hot water or steam. Some variations use ultra-violet light to cure the resin.

CIPP systems create a close-fit ‘pipe-within-a-pipe’ which has quantifiable structural strength and can be designed to suit various loading conditions. The ring-stiffness of the liner is enhanced by the restraint provided by the host pipe and the surrounding ground, but systems designed for gravity pipelines do not rely on a bond between the liner and the substrate. Systems which rely on the host pipe for some measure of structural support are sometimes known as ‘interactive lining’ techniques.

As well as minimizing bore reduction, an inherent advantage of cured-in-place liners is their ability to conform to almost any shape of pipe, making them suitable for relining non-circular cross-sections. Provided that the liner perimeter has been correctly measured and that the material does not shrink significantly during cure, a close-fit liner should result. Their main limitation is the wall thickness, and hence the quantity, weight and cost of material, which may be required for larger sizes or for severe loading conditions, particularly in non-circular pipes.

Laterals can be re-opened remotely after lining, but care must be taken during installation to ensure that surplus resin does not enter branches. CIPP systems are also available for lining laterals from within the main pipe.

The major disadvantage of CIPP lining systems is the need to take the host pipe out of service during installation and cure. In gravity pipes, where flows are very low, it may be possible to plug any incoming pipes and to rely on the storage within the system. In other cases flow diversion or over-pumping will generally be required. One way to overcome service intervention is with flow through plugs.