Horizontal Directional Drilling

Horizontal Directional Drilling (HDD)

Replacement is carried out off the existing pipeline by using a steerable installation technique. HDD is using a machine in which flexible rods are rotated and pushed, propelling a cutter which is generally slant-headed through the ground. Steering is accomplished by the reaction of the slant head against the ground when pushed without rotation. Supported by a location device, this enables a pilot hole to be established to a planned line and grade, after which the hole is enlarged by pulling back a rotating reamer. Simultaneously or in a separate process the product pipe is pulled into the bore hole.

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