Reducing vibration damage in underground pipelines

Construction activities and traffic loading from road and rail traffic create vibrations that travel through the ground as stress waves. When these vibrations encounter underground infrastructure such as pipelines, part of the wave is absorbed by the infrastructure while part is reflected. Over time this can have a detrimental effect on pipelines, reducing service life and increasing maintenance costs. kwik-ZIP has designed a spacer system that can help reduce the impact of these damaging vibrations on pipelines.

Stress waves created by vibration results in dynamic stress (fatigue) on pipelines, causing misalignment, and damage such as crack propagation, which can result in the failure of a pipeline.

Sharing the load

Jason Linaker, Managing Director at kwik-ZIP Spacers, said unlike traditional rigid pipe spacers the kwik-ZIP HDX range of spacers use a unique “load sharing runner” system.

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

“Unlike traditional rigid pipe spacers, the “load sharing runner” system also delivers a suspension and dampening effect, resulting in a reduction in the transfer of potentially damaging vibration and movement from the outer casing to the carrier pipe.

“This is particularly beneficial to projects where there are traffic or rail crossings and ongoing external vibration could affect the outer casing, resulting in increased service life and reducing maintenance costs associated with vibration related damage.”

Keeping the pipe isolated from the casing

The effects of vibration on service life can also be decreased by ensuring the pipeline is fully isolated from the casing.

“Across all pipeline construction and installations, spacing the carrier pipe away from the casing along the entire length is crucial to long-term pipe function, integrity and lifespan,” Mr Linaker said.

“Correct placement of the product pipe within the casing is also essential for grouting as this helps fix the pipe in position, allowing for a complete grout envelope around the pipe. The grout also helps to increase the new pipe’s ring stiffness and its resilience to external hydrostatic loads.

“kwik-ZIP HDX spacers are versatile and come in four runner heights up to 125 mm which can be combined and customised. This provides customers with a choice of runner heights to accommodate a broad range of pipe OD/casing inside diameter combinations.

“Installers can easily centralise pipes with various annular clearances, including the larger clearances and pipe flanges that are common with large OD pipe installations.”

The kwik-ZIP advantage

Designed and developed by drilling professionals, the kwik-ZIP HDX range of spacers handle pipe diameters from 100mm OD to greater than 1600mm.

Each spacer is manufactured from Kwik-ZIP’s engineered thermoplastic blend – a high-grade thermoplastic that is flexible, extremely tough and has a low coefficient of friction, and high resistance to organic chemicals, oils and synthetic detergents; even when immersed for long periods of time.