Aging pipelines are a major concern for water utilities as corroded and collapsing infrastructure can lead to problems such as water wastage, reduced efficiency, and health problems if metals seep into the water. Slip lining is a trenchless method of pipe refurbishment that involves inserting a new pipe into an existing pipe. Spacers can be used to help ensure the new pipe is fixed in place, and protected from corrosion, extending its lifespan.

The slip lining process

img_0016The new pipe is laid out above ground before being brought into an excavated pit and pushed or pulled through the existing pipe to an exit pit or manhole.

Once installed, the space between the two pipes is usually grouted to help fix the pipe in position and transfer load from the existing pipe. The grout helps to increase the new pipe’s ring stiffness and its resilience to external hydrostatic loads.

According to Jason Linaker, Managing Director at kwik-ZIP, spacers such as the HDX/HD series can help with the slip lining process.

“Using spacers during the slip lining process will protect the carrier pipe, make installation easier and extend the life of the new pipe.

“kwik-ZIP spacers also help contractors comply with design specifications of the project in a simple, versatile and cost effective way.”

Inserting the pipe

One of the problems that can occur during the slip lining process is abrasion. As the new pipe is pushed into the existing pipe, there is potential for the new pipe to be damaged in the process.

According to Mr Linaker, when a kwik-ZIP spacer is used, it creates the necessary clearance between the two pipes.

“By creating this clearance during the installation process, the new pipe is protected against any abrasion which may occur during installation, and over the lifetime of the pipeline.

“The runners on kwik-ZIP spacers also have a very low co-efficient of friction, allowing for the quick and easy insertion of the new pipe into the existing pipe.”

Furthermore, along with the grout, they also help help fix the pipe in position, ensuring the pipe stays secure.

Sharing the load

kwik-ZIP spacers can also increase the lifespan of the new pipe by helping with the transfer load due to their unique “load sharing runner” system.

“Each kwik-ZIP unit maximises its weight bearing capacity by distributing the pipe load across multiple runners, therefore, reducing point loading at any one location, boosting and optimising the overall support capacity of the spacer exponentially as pipe size increases,” Mr Linaker said.

This system also has a suspension and dampening effect which reduces the transfer of potentially damaging vibration and movement from the existing pipe to the new pipe.

Stopping corrosion

img_0017When inserting a new pipe into an existing corroded pipe there is a chance that corrosion can transfer. This transfer can occur if the new pipe is made from steel, or if metallic spacers are used. Even if the new pipe is not steel, corrosion can still breach the grout seal around the new pipe.

Mr Linaker said that kwik-ZIP systems prevent this from occurring as they are made from Kwik-ZIP’s engineered thermoplastic blend – a high-grade thermoplastic that is flexible, extremely tough and has a low coefficient of friction, which make them corrosive-free.

“As kwik-ZIP spacers are made from Kwik-ZIP’s engineered thermoplastic blend, they are resistant to the transfer of pre-existing corrosion and are also resistant to developing corrosions in installations involving water. This ensures they will remain intact throughout the life of the pipe.”

A simplified process

In Western Australia, Spannas Engineering used kwik-ZIP’s HDX 65 spacers during the relining an old steel trunk main crossing under Coalfields Highway in WA for the Water Corporation.

The existing pipeline had an internal diameter of approximately 722mm, and was relined with a 560mm OD HDPE pipe. Over a distance of 80m, kwik-ZIP spacers made the relining task easier for Spannas Engineering, all while also extending the life of the new pipe.

It’s a win-win situation for the contractor and the utility – and all it takes is a little space.