Material matters: pipelines benefit from thermoplastic spacers

Material matters for pipelines; the choice of material impacts the installation and lifecycle of the asset. This includes the material that spacers are manufactured from. While project costs need to be taken into account, the cost of taking shortcuts can quickly add up due to increased project installation time and reduced pipeline longevity. Choosing a spacer system manufactured from appropriate materials such as thermoplastic, will maintain the integrity of the pipe, as well as reduce delays, costs and reputational damage.

The problem with timber

Make-shift timber spacers are still commonly used in pipeline installations as a way to keep project costs down.

Jason Linaker, Managing Director at kwik-ZIP, said that while timber spacers reduce the installation costs of the pipeline, they will not last the lifecycle of the pipe and can cause serious problems.

“Over time, timber rots away, leaving either gaps in the grouting, or if grouting isn’t used, the pipe will move once the timber is no longer able to support the weight. There is also the risk with timber that it will wear away as it is run in during the installation process,” Mr Linaker said.

“Timber spacers are also a problem in environments with water as they will ultimately perish. This is why the Water Services Association of Australia (WSAA) introduced a new code (WSA PS 324) in 2015 which governs casing spacers for the water industry.

“This code provides clarity when it comes to choosing the best spacer to ensure the longevity and success of the pipe installation. It means that if you are installing a water or wastewater pipeline and fail to use the correct type of spacer for the carrier pipe, you are not complying with WSAA’s standard. Timber simply doesn’t comply with it.

“Currently, kwik-ZIP’s HDX range is the first and only spacer system to be successfully appraised against this code.”

While make-shift timber spacers might reduce the cost of materials for a pipeline installation they can cost projects in time.

“Timber spacers are difficult to install, cumbersome, and hard to secure accurately, making them time-consuming. Products such as our HDX spacer will make up the extra costs for the materials by speeding up the installation as they have been designed specifically to be quick and easy to assemble on-site,” Mr Linaker said.

Corroding of metallic spacers

Metal is also a commonly used material to manufacture spacers, however, they are not without problems.

Metallic spacers have a track record of damaging plastic pipes such as fibreglass or glass reinforced plastic (GRP), and can greatly reduce the lifespan of a pipeline installation. Any movement of a metallic spacer can cause damage to the carrier pipe.

There is also a high chance of corrosion damage. If a new pipe is inserted into an existing corroded pipe there is a chance that corrosion can transfer if metallic spacers are used. Even if the new pipe is not steel, corrosion can still breach the grout seal around the new pipe.

“Acidic soil conditions also pose a problem for metallic spacers if they come in contact, which is a possibility if soil is left behind in the annulus after the installation of a road or river crossing,” Mr Linaker said.

“Even stainless steel is subject to accelerated corrosion from acidic soil conditions. Such corrosion can be transferred via the metallic spacer to the pipeline itself if it’s made from steel.”

A thermoplastic solution

Mr Linaker said that kwik-ZIP systems provide a solution to the problems presented by timber and metallic spacers as they are made from a high grade thermoplastic called ACETAL POM, which prevents them from rotting, and is corrosive-free.

“As kwik-ZIP spacers are made from ACETAL POM they are resistant to the transfer of pre-existing corrosion, and are also resistant to developing corrosion in installations involving water. This ensures they will remain intact throughout the life of the pipe,” Mr Linaker said.

“They also have a flexible design, allowing them to be installed with a clearance of between 38 and 125mm between the pipeline and the casing to protect the pipe against any abrasion which may occur during installation, and over the lifetime of the pipeline.

“They also have a low friction coefficient to make it easy for the pipe/casing to be inserted.

“Although spacers are usually a small part of the overall pipe installation process, choosing a spacer made from an appropriate material can significantly increase the life expectancy of the carrier pipe by keeping them free from corrosion, casing damage and overall wear.”

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