Progress in pipe protection

In early 2015 PipeSak was given a challenge – develop something to replace wood lagging that can withstand extreme impacts. At the time, PipeSak was preparing for a field trial utilising PipePillo® Structured Pipeline Supports for stringing and welding applications on a major 48 in. (1219 mm) OD project in Ontario, Canada. The 48 in. OD pipeline under crossed three hotlines that needed to be protected in multiple locations. Both the owning company and contractor expressed concerns about wood lagging – it was cumbersome, expensive, and unreliable. As it turned out, the founder of PipeSak, Geoff Connors, P. Eng, had already been working on the design of a pipeline protection wrap for extreme applications that was easy to install, cost effective and, most importantly, engineered to withstand severe impacts.

PipeSak ended up with two field trials on that project (Figure 1) and the concept of PipeDefender® became a reality. By 2023, after successfully protecting pipelines in some of the most extreme construction conditions in North America, PipeDefender won the International Pipe Line and Offshore Contractor Association (IPLCOA) New Technology award for its significant contribution to innovation in pipeline construction.

Pipe protection methods

With a growing emphasis on pipeline integrity, design engineers are always looking for better methods to protect their pipelines. A key consideration during pipeline construction is how to protect anti-corrosion coatings efficiently and economically, especially in harsh environments where standard rock shields are not enough.

PipeDefender was initially developed to overcome the many inherent shortcomings of traditional pipe protection methods utilised in areas of extreme rock.

Compacted sand

Compacted sand has been a preferred method to bed and support pipelines in rocky trenches. Compacted sand can be costly and labour intensive to supply and install – especially in remote areas. When groundwater eventually returns to the trench the expensive sand padding will dilute or even migrate away from the pipeline, exposing the surrounding soil and stone it was meant to protect against. Denting, ovality and corrosion are now concerns for the remaining life of the pipeline.

Wood lagging

Wood lagging has always been a popular option for North American pipelines when sufficient sand is not available. Wood lagging is comprised of multiple planks of 2 x 4 in. (38 x 89 mm) lumber that are drilled and threaded together with thick steel cables that are later fastened to the pipe with steel banding. Installation of wood lagging is always a cumbersome process and presents numerous safety issues due to the combined weight and awkwardness – especially for large diameter pipelines. The organic material (wood) will deteriorate over time, creating the potential for surrounding rocks to compress against the pipe. The remaining steel components may interfere with the pipelines’ cathodic protection (CP) systems, multiplying the risk. Often, traditional rock shields are installed under the lagging to help reduce some of these concerns, however, the possibility for denting and ovality still remain.

Thin film concrete coating

Thin film concrete coating is a layer of concrete typically 1 -2 in. (25 - 50 mm) thick applied to the outside of a pipeline either near site or at a plant. The coating is used primarily to protect against mechanical damage from large rocks present in the trench or from backfilling. Depending on the thickness of the coating, this can roughly double the weight of the empty pipe, significantly increasing logistical and equipment requirements on top of the already expensive up-front costs. Bending the pipe also becomes difficult or impossible which further restricts the use of concrete coatings.

An improved solution

PipeDefender was designed to address the need for an improved, permanent solution to protect pipelines in rugged, rocky environments. Engineered with a pattern of peaks and valleys, PipeDefender not only disperses the force of impact, but also absorbs it through deformation. Both controlled laboratory testing and large-scale field trials have proven PipeDefender resists rock impacts in excess of 60 lb (27 kg) when dropped from a height of 10 ft (3 m) – with no fusion bonded epoxy (FBE) coating damage. Using PipeDefender will not only protect corrosion coatings from damage, the many drainage holes in PipeDefender allow for the passage of ground water and CP currents. PipeDefender is lighter, faster to install, and easier to work with compared to both thin film concrete coating and wood lagging, offering both improved safety and reduced costs. PipeDefender works with rolling cradles (Figure 2) and, once placed in the trench, can be backfilled with native and blasted rock – sand bedding/padding is no longer necessary to support and protect the pipe.

Design criteria

In conjunction with pipeline owning companies, contractors and engineering firms, PipeSak evaluated current methods of mechanical pipeline protection and developed the following criteria for the ideal solution:

Must be compatible with CP systems and allow the free passage of water.

Must provide equal or better mechanical protection than current methods.

Should be light enough to be easily handled without equipment (i.e. labourers only) and simple to install. Must be resistant to UV degradation.

Resistant to a wide range of pH levels and chemicals that could be found in soil.

Through the use of state-of-the-art engineering software, finite element modelling and numerous design iterations, a continuous ribbed profile was found to be optimal. With a shape determined, physical models were created and large-scale field testing was carried out.

Testing and technical information

PipeSak works with well respected, industry recognised ASTM certified testing facilities. Published test results on PipeDefender provide the following conclusions…

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