Horizontal Directional Drilling
What is Horizontal Directional Drilling?
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Horizontal Directional Drilling (HDD) is a method of installing underground pipelines, cables and service conduit through trenchless methods.
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Horizontal Directional Drilling is a method/technique within the Underground Construction industry.
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It involves the use of a directional drilling machine, and associated attachments, to accurately drill along the chosen bore path and back ream the required pipe.
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Directional boring or horizontal directional drilling is also used in the installation of utility pipelines and conduits.
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Directional boring or horizontal directional drilling is a way to get utilities from one point to another without destroying the existing ground or obstacles that are in between the two points.
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Horizontal directional drilling goes above and beyond traditional trenching; connecting utilities and services in places that traditional trenching is impossible.
How does Horizontal Directional Drilling Work?
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Horizontal Direction Drilling is comprised of three stages:
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Pilot Bore
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Reaming
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Product Pipe Installation
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Stage 1 - Pilot Bore
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The drill bit is connected to a rotating drill pipe and pushed into the location designated for the borehole. It is guided through the boring process until it emerges on the opposite side of the boring project.
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Drilling fluids, or drilling mud is a mixture of water and bentonite clay and is very important to the operation. This drilling fluid is used in guiding the drill bit as it bores the hole. It also stabilizes the borehole and acts as a lubricant and coolant for the drill bit.
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Additionally, the drilling fluid carries all the soil, heavy metals, and bedrock cuttings out of the borehole back to the drill rig location. The drilling fluid is then separated from the cuttings and recycled back into the boring process.
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Finally, the drill bit will exit the borehole at the exit pit.
Stage 2 - Reaming
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A reaming tool is then attached to the drill pipe and pulled back through the borehole.
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Successively larger reaming tools are pulled back and forth through the borehole until the hole is about one and a half times the size of the pipe that will be installed.
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Finally, a swab pass reamer is pulled through the hole to verify all is clear and ready to pull the pipeline through.
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This swab pass reaming tool is sized bigger than the pipe to be installed but smaller than the largest reaming already accomplished.
Stage 3 - Product Pipe Installation
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Pipes are brought to the exit location and welded or fused together, coated, x-rayed, and pressure-tested.
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Product pipe is then connected to a pullhead.
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The completed pipe string, a little longer than the bored hole, is placed on rollers in preparation to be pulled through the borehole.
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It is then positioned and angled to make the pull as easy as possible with minimum resistance. Once totally fabricated, tested, and properly positioned the pullback process begins.
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When the pipeline emerges at the drill rig location, it is then checked, surveyed, and tested.
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Lastly the work sites are cleared of equipment and restored to preexisting conditions.
Why use Horizontal Directional Drilling?
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Directional boring or horizontal directional drilling is a way to get utilities from one point to another without destroying the existing ground or obstacles that are in between the two points.
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Horizontal directional drilling goes above and beyond traditional trenching; connecting utilities and services in places that traditional trenching is impossible.
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Directional boring is mainly used for making crossings under rivers, roads, and existing structures, with the purpose of installing pipes and conduits to transport different types of fluids and materials.
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The HDD technique has the less construction and restoration cost of new water and wastewater pipes and for rehabilitation of failing pipes in urban areas where excavation is not required or impossible.
Who invented Horizontal Directional Drilling?
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Martin Cherrington
When did Horizontal Directional Drilling start?
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Horizontal directional drilling is an idea Martin Cherrington first conjured up in the early 1960s when he was working for a utility installation company in Los Angeles.
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While out on a job, he witnessed another company doing some work nearby, using a hand-held air drill for a gas line installation.
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From that, Cherrington became familiar with the concept of guided drilling and wanted to take it a step further. He ended up taking it several steps further.