Casing Spacers (also known as insulators), while only a small component, can have a big impact on a pipeline’s lifecycle so it’s important to choose the right product to ensure its integrity is maintained, and costs are kept to the minimum. At kwik-ZIP, we look at what you should take into account when selecting a casing spacer system.
Jason Linaker, Managing Director at kwik-ZIP, said there are a number of factors to take into consideration when choosing the right casing spacer, and having the right information will ensure your project will have the biggest chance of success.
“Although casing spacers are usually a small part of the overall pipe installation process, correctly designed and fitted casing spacers can significantly increase the pipeline’s life expectancy by keeping it free from corrosion, casing damage and overall wear,” Mr Linaker said.
Casing Insulators – Why the material of your casing spacer matters
Casing spacers or insulators can be manufactured from a number of materials, and the chosen material can impact on the longevity of the pipeline, as well as long-term costs.
The Water Services Association of Australia’s (WSAA) product specification for correct protection of carrier pipes when installed inside casings, WSA PS-324, is one source of information that contractors can refer to to ensure they are using the most appropriate casing spacer product.
Mr Linaker said the standard outlines various requirements for the casing spacer, including use of materials, abrasion resistance, wear pads, runner height flexibility and minimum runner spacing around the pipe.
“While the specification is aimed at water pipeline installations, these elements are relevant to all pipeline installations where there is a carrier pipe, as they help to prevent problems experienced during these installations across the board such as abrasion, and achieving correct grade and alignment.”
Getting the best results from your casing spacer
Two commonly used casing spacer materials are timber and metal, however while these may provide initial project cost savings, they do not comply with the WSAA specification, and could cost the asset owner more in the long term as they can have a negative effect on the longevity of the pipeline.
Metal casing spacers are commonly used in water and gas pipeline installations, however, they present several problems.
“Metallic casing spacers are prone to corrosion in installations where acid soil conditions, water or existing corrosion are present,” Mr Linaker said.
“When corrosion occurs it can breach the grout seal around the new pipe and be transferred via the metallic casing spacer to the pipeline itself whether it’s made from steel or plastic.
“Metallic casing spacers also have a track record of damaging plastic pipes such as fibreglass or glass reinforced plastic (GRP).”
Mask-shift timber spacers are also commonly used as a cheap alternative to other materials available.
While make-shift timber casing spacers may be more cost effective than other materials, there are long-term negative consequences for the durability of the pipeline that need to be considered.
“It is still surprisingly common for contractors to use make-shift timber casing spacers, which is concerning. Not only do these not meet the WSAA specification but they simply will not last the lifetime of the pipeline and could lead to costly maintenance or replacement,” Mr Linaker said.
“The problem with timer is that over time it 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.
“Furthermore, a material like timber will not last in an environment where water is present, which is why the specification requires casing spacers to be manufactured from inert materials.”
A single system solution: inert, flexible and low friction insulators
Mr Linaker said when it comes to choosing a casing spacer system, selecting a product made from high grade thermoplastic, such as kwik-ZIP spacers, will make the installation easier and extend the life of your asset.
“kwik-ZIP casing spacers 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, ensuring they are corrosive-free so they won’t transfer existing corrosion to the new pipe, and as they are resistant to installations involving water, including seawater, the casing spacers themselves will not corrode or rot,” Mr Linaker said.
“They are also the only product in Australia that is approved by WSAA against WSA PS-324.”
kwik-ZIP casing spacers also have a flexible design. This means the same product can be used across a project as various runner heights can be achieved, allowing for different pipe/casing combinations.
“Typically, casing spacers will be manufactured to fit a particular pipe diameter. This means that different sizes of casing spacers are required for different pipe diameters,” Mr Linaker said.
“kwik-ZIP casing spacers, however, are designed to be adjustable, meaning that the same casing spacers can be used for varying pipe diameters – adding an extra layer of flexibility. If you order too many casing spacers, they can just be used on your next job; and if your job requires a variety of annular clearances, the same casing spacers can be adjusted to meet the needs across a project.”
“Because you only need one product group across the whole job site, this cuts down on confusion about which product to use where, and speeds up installation.”
kwik-ZIP casing spacers are also constructed with wear pads on the runners. This gives them a low friction coefficient, making it easy for the pipe/casing to be inserted without damaging it.