Wood lagging is a method of banding wooden slats around pipelines to protect against

impact Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impac ...

, abrasion, and

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...

. Wooden lagging acts as a sheath, protecting the pipeline from damage, and is especially useful in rocky terrain; steep inclines; around rivers or swampy areas; and other rough terrain. Boiler lagging is akin to pipe lagging, but is used to protect steam boilers. Wood lagging has been used on notable pipelines such as The Trans-Mountain Pipeline, which spans the Canadian Rockies, since 1953, and The Kinder Morgan TMX Anchor Loop. The latter, constructed in 2007, used wood lagging in the environmentally-sensitive terrain and river crossings of

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Jasper National Park Jasper National Park is a national park in Alberta, Canada. It is the largest national park within Alberta's Rocky Mountains spanning . It was established as a national park in 1930 and declared a UNESCO World Heritage Site in 1984. Its locatio ...

Overview

Construction process

Wood lagging is one of several solutions employed by

pipeline Pipeline may refer to: Electronics, computers and computing * Pipeline (computing), a chain of data-processing stages or a CPU optimization found on ** Instruction pipelining, a technique for implementing instruction-level parallelism within a s ...

engineers to provide mechanical protection for underground pipelines. Others include

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

coating, rockshield,

high-density polyethylene High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...

, imported sand padding, and padding machines. Wood lagging involves wiring a series of wooden slats together to create a 'blanket'. This blanket of wooden slats is then dropped over and wrapped around the outside of a pipeline, with or without coating, and secured with steel or plastic banding. Once wood lagging is installed, the pipeline can be buried and backfilled. (Wood lagging is installed as part of the “padding and backfill” stage of construction.) For pipelines that encounter saturated soils or water, wood lagging is often installed in between bolt-on concrete weights, acting as a spacer to keep the weights in place as well as to provide mechanical protection to the pipe. River weights are generally used at river and creek crossings to counteract the

buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the ...

of pipelines in stream, high water table situations, or in swampy areas.

Characteristics

Wood lagging is especially useful to protect pipelines in rocky terrain; steep inclines; around rivers or swampy areas; and in areas with poor natural availability of padding, such as sand or gravel. Wood lagging is light, flexible, and easy to install at

construction Construction is a general term meaning the art and science to form Physical object, objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Pr ...

sites. As a method for protecting pipelines, wood lagging offers high-impact resistance at a considerably reduced cost compared to other types of pipeline protection, such as

coating. Materials for wood lagging can often be sourced regionally near pipeline construction sites, reducing transportation time and costs.

Wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

used in wood lagging is a

renewable A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace the portion depleted by usage and consumption, either through natural reproduction or other recurring processes in a finite amount of ti ...

resource that creates a

carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in lan ...

effect after pipeline burial, providing minimal environmental impact compared to other types of pipeline protection.

Historic and modern uses

The longevity of wood lagging that has been installed underground is unknown. However, intact wood lagging has been found still performing its function more than 50 years after installation: GWR Firefly

*The Trans-Mountain Pipeline, which spans the Canadian Rockies, the mountainous region of central

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

, and 98 streams and rivers, used wood lagging to protect an expanse of pipe crossing the Coquihalla Canyon. Archival film footage shows the use of wood lagging during its installation in 1953. Modern examples of wood lagging used to protect

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...

and

natural gas pipeline Pipeline transport is the long-distance transportation of a liquid or gas through a system of pipes—a pipeline—typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 countr ...

s include: *The BC Gas Southern Crossing Pipeline, constructed in 2000. Wood lagging was used in approximately 22 km of the 315 km pipeline route. *The Kinder Morgan TMX Anchor Loop, constructed in 2007 by Kinder Morgan Energy Partners. Wood lagging was used to protect the pipeline in the environmentally-sensitive terrain and river crossings in

. In this case, two-by-four inch slats were strapped over the pipes to provide extra protection against the rough terrain of the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...

. *Sun Canadian's company policy is to cover exposed pipes with wood lagging. A different, but related, use of wooden slats was for lagging steam boilers, for example in trains.

References

External links