Case study: Te Maunga Outfall (Landward Section) construction works
For many years, Kwik-ZIP casing spacers and centralisers have been used across a wide range of industries in Australia, New Zealand and beyond. Casing spacers enable a central bolt, anchor or pipe to be held away from the walls of a hole or casing, by a product that is inert, simple to install and will last the life of the asset.
There are many reasons this may be required. In anchoring, it’s to allow maximum grout cover. Water well drillers use spacers to install screens. In the civil engineering environment, it’s to reduce the transmission of vibration, from the casing to the product pipe, and to allow grouting.
Regardless of the industry, there is a solution to suit your project's needs. In the Te Maunga landward outfall case study below - the spacers were primarily used to centralise the product pipe and maintain the grade over the life of the asset. They also allow the product pipe to be slip lined inside a concrete carrier pipe, with a wide variety of joint gaps and lips that had to be negotiated.
Read the case study below to see how the combination of Kwik-ZIP casing spacers, and technical support from Blick, were able to solve a challenge on the Te Maunga landward outfall project.
Te Maunga Outfall (Landward Section) construction works case study
The Te Maunga Outfall (Landward Section) construction works was tendered by Tauranga City Council in 2020, and took place during 2021.
The project included installing 100m of DN1200mm OD HDPE pipe (high-density polyethylene) in an existing 1500mm concrete duct, under the Tauranga Eastern Link (TEL). The TEL is a four lane motorway that carries 21,000 vehicles a day, and has a rail line servicing Tauranga adjacent to it.
HEB won the tender, and casing spacers were chosen for installation - for their ability to support the weight of the product pipe at full load. They also allowed the DN1200mm OD HDPE pipe to be installed with minimal pull force and no damage.
Kwik-ZIP® HDX and HDXT casing spacers are commonly recommended and used for applications like this. HEB staff had used Kwik-ZIP® spacers previously on the Waiāri Water Supply Scheme, and understood how easily the spacers were able to be fitted.
Blick are the New Zealand and Pacific Island distributors of Kwik-ZIP® casing spacers, and consulted with HEB for this project.
Clay Adams, Technical Sales Manager at Blick, said
“This installation had some interesting challenges to overcome. Internal video of the casing pipe, which ran under the TEL, showed pipe joints that were aligned in such a way that they had variable joint spacing, as well as lip heights ranging up to 10mm.
We needed a solution that would allow the casing spacers to bridge joint gaps and ride over the lips. The further the pipe was installed, the more lips would be encountered, increasing resistance.
In addition, there was a cement ramp to be negotiated, to allow the casing spacers to ride up and onto the final section of casing pipe, which would need to be traversed.”
With critical infrastructure running over the pipe route, the product had to be installed by slip lining. After studying video footage of the casing pipe, Blick was able to recommend a solution, to allow the pipe to be installed at low pull back pressures with low risk. The HDXT 103 casing spacers feature a load sharing suspension system, manufactured from Kwik-ZIP’s engineered thermoplastic blend which has a low coefficient of friction. This allows each casing spacer set to traverse the uneven casing pipe.
In cases like the Te Maunga Outfall project, casing spacers assist in solving a number of technical challenges. Not only do they maintain the product pipe on grade in the casing pipe for the life of the installation, they also provide a mechanism for installing product pipe in a way that protects it, while allowing it to be installed in, at times, a challenging casing pipe.
The combination of working with a product that has been used successfully worldwide (including in Australia and New Zealand), and access to the expertise of Blick and Kwik-ZIP at design and through execution, provided the best opportunity for low risk and effective execution.
