Meghan Connors, President, PipeSak® Incorporated & PipeSak® USA, Inc, describes how the next generation of rockshields are improving pipeline coating protection as well as providing faster installation times.
As demand for oil and gas increases, so do the pipeline diameters needed to transport it, requiring deeper trench excavations. As trenches get deeper, the occurrence of rock and stone in the soil increases. Damage to pipeline coatings, whether during installation or throughout their operational lifespan, can lead to costly repairs and compromised performance and safety.
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Protecting pipeline coatings
The biggest risk to long-term pipeline integrity is corrosion. To prevent this, a two-fold system is used: pipelines are coated, often with fusion bond epoxy (FBE) or similar coatings, to protect them from the elements, and a cathodic protection (CP) system is installed to reverse corrosion if the coating is damaged. Protecting the pipeline coatings during construction is critical, especially in areas with rocks and stones. Sharp rocks can damage pipeline coatings and hinder the electrical currents required for effective CP. To mitigate this risk, various protection methods are used depending on the rock type and size, including thin film concrete coatings and rockshields, often combined with sand padding.
Traditional rockshields
Rockshields, which are wrapped around the pipe in the field prior to lowering in the trench, are often the most economical and flexible method used to protect pipeline coatings in areas were smaller rocks and stone (< 6 in./152 mm) are present. Over the years, several types of rockshield have been developed and brought to market with varying degrees of success.
Traditionally, the most commonly used rockshield styles include:
Stranded rockshields
Stranded rockshields are manufactured by melting and extruding flexible polymers, most commonly polyvinyl chloride (PVC) with additives such as blowing agents and fillers, into a randomized, spaghetti-like pattern. Once referred to as the ‘gold standard’ in rockshields, stranded PVC is typically the most expensive option, both in initial purchase cost and installation costs. This is mainly due to the weight of the product – stranded rockshields are heavy, resulting in higher material and transportation costs. They are also cumbersome to install, requiring several labourers to wrap it around the pipe and spiral tape it to hold it in place.
Extruded grid patterned rockshields
Grid patterned rockshields have gained market share over the past several years mostly due to the low cost of manufacture. They are typically extruded from high density polyethylene (HDPE) with a higher concentration of blowing agents to ‘foam’ the plastic, resulting in a lighter weight finished product. While grid patterned rockshields are lighter, reducing initial purchase and transportation costs, they are still cumbersome to install. In cold weather conditions they may become stiff and difficult to handle, slowing down installation.
Issues with traditional rockshields
Void space
It’s essential that rockshields, or any material in long-term contact with the pipe, don’t interfere with cathodic protection (CP) systems. Traditional stranded and grid-patterned rockshields allow CP electrical currents to pass through void spaces, exposing the pipe (see Figure 1). This is particularly problematic with grid-patterned rockshields, where evenly spaced holes can let sharp, angular rocks damage pipeline coatings. Smaller rocks may also become trapped between the rockshield and pipe, increasing the risk of coating scouring. Stranded rockshields offer better protection due to their overlapping design, but the risk of rocks penetrating still exists. To address this, some companies attach a thin, needle-punched fabric to the underside of the rockshield, helping prevent small rocks from getting between the rockshield and pipe. However, this does not provide additional protection against sharp, angular rocks.
Installation costs
Rockshields are applied in the field by workers prior to the lowering in process. Rockshields for small diameter pipelines, under 24 in. (610 mm) outer diameter (OD), are usually supplied in 30-50 ft. (9 – 15 m) rolls, which are walked down the pipe and either cigarette or spiral-wrapped. Rockshield for larger OD pipelines is usually supplied as pads that are wrapped around the pipe, one at a time, and overlapped. Traditional rockshields are affixed to the pipe by spiral-wrapping tape – a time consuming and tedious process often requiring workers on either side of the pipe. In pipeline construction, time is money – the longer it takes to install, the higher the labour costs.
Worker safety
A top concern on any pipeline construction project is worker safety. When a pipe is strung out along the right or way, the workers are supposed to remain on the work side of the pipe – away from the trench. When installing traditional rockshields, particularly on large OD pipelines, this is often impossible. At least one worker needs to be ditch-side, with their back to the trench, in order to affix the tape – increasing the risk of a workplace accident.
Next generation rockshields
In the past, PipeSak® manufactured and marketed a stranded rockshield called PipeJacket®. While the random strand design of PipeJacket® and similar rockshields is superior to a grid pattern design, there had to be something better. PipeSak® engineers set out to develop a new style of rockshield that addressed the concerns of both the engineers designing pipelines, and the contractors building them.
After extensive R&D, laboratory testing and field trials, PipeSak launched RockStop® Pipeline Protection wrap. RockStop® rockshield is a lightweight non-woven geotextile made of a proprietary blend of fibres that offers best in class, 360˚ impact, puncture and abrasion protection. It works with cathodic protection systems, and installs in a fraction of the time as traditional rockshields. RockStop® rockshield can be safely installed with the Velcro-like QuikStrips® or permanently sealed using Pipesak’s® low temp Heat Tool.
Engineered for maximum protection
RockStop® rockshield outperforms any other field applied rockshield on the market, protecting large OD pipe from up to 8 in. (203 mm) rock impacts dropped from a height of 6 ft. (1.83 m). Extensive third-party testing in ASTM certified facilities has proven RockStop® rockshield to be superior in every category including impact strength, puncture strength and abrasion resistance. RockStop® rockshield does not inhibit cathodic protection systems and remains flexible to temperatures as low as -65˚ F (-54˚ C).
Cathodic protection compatibility
RockStop® rockshield was specifically designed to prevent impact and puncture-related corrosion with an engineered interlocking proprietary blend of fibres that still allow the movement of groundwater to and from the pipeline surface for cathodic protection systems. RockStop® rockshield has a permeability similar to a clean sand, ensuring water will drain from RockStop® rockshield as it does from sand padding or sandy backfill.
Installation advantages
The real advantage of RockStop® rockshield is the installation. It was designed with contractors in mind – it is faster, safer, and more economical then traditional rockshields.
Speed of installation
A controlled field trial on a 48 in. (1219 mm) OD pipe comparing RockStop® rockshield installation methods with standard spiral tape installation showed that RockStop® rockshield can be installed 3 times faster than traditional rockshields. RockStop® rockshield offers two methods of installation:
- QuikStrip® fasteners: QuikStrip fasteners are nylon strips with polypropylene hooks specifically designed for use with RockStop® rockshield and are supplied pre-cut in 8-12 in. (203 mm – 305 mm) lengths. QuikStrip fasteners have extreme shear and peel strength and are strong enough to be used with rolling cradles – but can be easily removed if required.
- RockStop® LT Heat Tool: RockStop® rockshield is designed with a proprietary fibre composition that allows it to be heat-sealed using our low temperature heat tool to create a permanent seal (see Figure 6). RockStop® rockshield adheres to itself permanently in seconds, dramatically decreasing installation time. When heat sealed, RockStop® rockshield will continue protecting the pipeline coatings for the life of the pipeline, a major benefit in areas prone to ground movement or floods.
Lightweight, soft and flexible
One of the biggest complaints heard from installation crews on the right-of-way is the difficulty handling traditional rockshields. Stranded rockshields can be heavy and awkward to install and, without expensive additives, can become brittle in extreme cold. Grid-type extruded rockshields are known to be sharp and rough on the hands and can become stiff and difficult to wrap around the pipe in cold weather conditions. RockStop® rockshield was designed for the -22° F (-30° C) weather of the Rocky Mountains. It remains lightweight and flexible in all weather conditions.
Safe and economical
RockStop® rockshield is up to 50% lighter than traditional stranded rockshields and is manufactured from fine poly fibres ensuring it is always flexible and soft on the hands. It can be installed with less workers and, most importantly, with no worker ditch-side. With RockStop’s® lightweight design, the contractor will realise savings on labour and efficiency, as well as being more economical to manufacture, transport, and handle compared to other rockshields on the market.
Major project Highlights
TC Energy 48 in (1219.2mm) Costal GasLink (CGL)
TC Energy 48 in. (1219 mm) Coastal GasLink (CGL) The Coastal GasLink pipeline project is approximately 416 miles (670 km) of 48 in. (1219 mm) OD pipe traversing some of the most challenging terrain in Western Canada. The pipeline transports 2.1 billion ft3/d of natural gas across northern British Columbia to the LNG Canada facility in Kitimat for export to global markets.
The CGL pipeline route not only traversed rocky terrain but the Rocky Mountains themselves – it was arguably the most challenging pipeline construction project in Canadian history. RockStop® rockshield was used extensively during the three year construction project, along with PipeDefender® engineered pipeline lagging and PipePillo® pipe stands, to provide 360° of pipeline protection. The RockStop® rockshield adheres especially securely to the pipe when using QuikStrip fasteners for installation. The contractor was able to move protected pipe using slings, rolling cradles, and even cranes with no risk of the RockStop rockshield shifting (see Figure 7).
Williams 30 in./ 42 in. (762 mm / 1067 mm) Regional Energy Access (REA)
The Regional Energy Access Project increased natural gas capacity by 829 400 million ft3/d along Transco’s existing transmission system, which transports Marcellus shale gas to customers in Pennsylvania, New Jersey and Maryland. The project involved constructing two pipeline loops running parallel to the existing Transco System in Pennsylvania including 22.3 miles (35.9 km) of 30 in. (762 mm) OD pipeline (Regional Energy Lateral) and 13.8 miles (22 km) of 42 in. (1067 mm) OD pipeline (Effort Loop). RockStop® was used to protect 18 miles (29 km) of the 30 in. OD line through rocky terrain. The speed of installation and the resulting cost savings was a major benefit for the contractor, who heat sealed the RockStop® using PipeSak’s low-temp heat tool. The contractor was able to install RockStop® in a fraction of the time compared to traditional rockshield installation (see Figure 8).
Enbridge East Tennessee 24 in. (610 mm) Natural Gas System Alignment (ETNG SA)
The ETNG System Alignment Program aims to improve the reliability and affordability of natural gas to regional utilities and power generators. It does this by increasing pipeline capacity and adding two new compressor stations across three states. The project began in late 2024, with a planned 16.5 miles of new 24 in. (610 mm) pipeline in Tennessee. This will run alongside an existing 16 in. (406 mm) pipeline and 6.5 miles of 24 in. (610 mm) pipe in Virginia. RockStop® was selected for the project due to its fast installation, worker safety, and mechanical protection properties. The project is ongoing, but after installing 4 miles of RockStop, the contractor has realized substantial savings. These savings include both the initial purchase price and reduced labor costs.
Conclusion
Pipeline projects often encounter diverse geological and environmental challenges. Traditional pipeline rockshields often provide uneven protection and require labor-intensive installation, delaying construction and increasing costs. By combining advanced materials with a user-friendly design, operators can permanently protect pipeline coatings from damage. This approach also enhances productivity, efficiency, and worker safety during installation.
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