Directional Drilling

Horizontal Directional Drilling

Directional DrillingHorizontal Directional Drilling or HDD, is a steerable trenchless method of installing underground pipes, conduits and cables in a shallow arc along a prescribed bore path by using a surface launched drilling rig, with minimal impact on the surrounding area.

Directional boring is used when trenching or excavating is not practical. Directional boring minimizes environmental disruption.

It is suitable for a variety of soil conditions and jobs including road, landscape and river crossings. Installation lengths up to 6,500' (2,000m) have been completed, and diameters up to 56" (1,200mm) have been installed in shorter runs.

Pipes can be made of materials such as PVC, polyethylene, Ductile iron, and steel if the pipes can be pulled through the drilled hole.


Directional boring is used for installing infrastructure such as telecommunications & power cable conduits, water lines, sewer lines, gas lines, oil lines, product pipelines and environmental remediation casings.

It is used for crossing waterways, roadways, shore approaches, congested areas, environmentally sensitive areas, and areas where other methods are costlier.

It is used instead of other techniques to provide less traffic disruption, lower cost, deeper and/or longer installation, no access pit, shorter completion times, directional capabilities, and environmental safety.

The technique has extensive use in urban areas for developing subsurface utilities as it helps in avoiding extensive open cut trenches.

The use however necessitates that the operator must have the complete information about the existing utilities so the he can plan his hole alignment to avoid damaging those utilities.

Since uncontrolled drilling can lead to such damages different agencies/government authorities owning the urban 'right-of-way' or the utilities have formed their rules for safe work execution.

For standardization of the techniques different trenchless technology promoting organizations have developed guidelines for this technique.


The method comprises a three stage process, wherein first stage drills a pilot hole on the designed path, the second stage enlarges the hole by passing a larger cutting tool termed as Reamer, and the third stage places the product or casing pipe in the enlarged hole.

The directional control capabilities assist the rig operator in making necessary changes in the directions of the drilling head.

Horizontal directional drilling is done with the help of a viscous fluid known as drilling fluid. It is a mixture of water and, usually, bentonite or polymer continuously pumped to the cutting head or drill bit to facilitate the removal of cuttings, stabilize the bore hole, cool the cutting head, and lubricate the passage of the product pipe

Locating and guidance

Directional Drilling Pipe InstallationLocation and guidance of the drilling is very important part of the drilling operation as the drilling head is under the ground while drilling and in most cases not visible from the ground surface.

Uncontrolled or unguided drilling can lead to substantial destruction, which can be eliminated by properly locating and guiding the drill head.

There are two types of locating equipment for locating the bore head: the 'walk-over' locating system or a 'wire-line' locating system.

In both of the systems a sonde, or transmitter, behind the bore head registers angle, rotation, direction and temperature data. This information is encoded into an electro-magnetic signal and transmitted through the ground to the surface in a walk-over system.

At the surface a receiver (usually a hand-held 'locator') is manually positioned over the sonde, the signal decoded and steering directions are relayed to the bore machine operator. In a wireline system, this information is transmitted through the cable fitted within the drill string.

Both systems have their own merits and depending upon the site requirements a particular system is chosen.

Directional drilling offers the following benefits:

  • Short, medium or long lengths of pipe

  • Pipes can be installed either straight or curved to steer clear of obstacles

  • By boring underground the working area is confined to points of entry and exit only

  • No Disruption to road, river or rail traffic

  • HDD is relatively quick and in many cases has lower overall costs

  • HDD is unaffected by surface obstacles

  • HDD is used to install pipes in changeable ground conditions

  • Pipes can be of any material which can be jointed into a continuous length, including steel & polyethylene

  • Mud recycling and biodegradable drilling fluids reduce waste

  • Accuracies +/- 100mm can be achieved

  • Equipment works from surface with no need for deep excavations

  • Suitable for a variety of ground conditions including clay, sands, chalks, ballasts and gravels

Contact Us

FlowTEK HDD UK Limited
Unit 1 Eco Business Park
Eco Way



01302 841936







English French German Polish Russian Spanish Welsh

Latest News

Flowtek have recently completed x3 drills installing 355mm Water Mains at Earnsdale Reservoir. 

The ground conditions consisted of very dense patches of rock, silt/ sands amongst clay. 

With such a variety of drilling conditions Flowtek utilised our Vermeer D40X55 and All Terrain Rock Drill along with our mud recycling unit, to succesfully complete all 3 drills within the timescale provided.

Flowtek have been involved with the A14 diversion of utilities, we have completed a mixture of 250mm and 355mm drills.

We have also completed 5 x 355mm water crossings in Scotland, across ditches and roads.


 Company Number: 8261380 VAT Registration Number: 157 0325 26 Registered Office: Unit 1 Eco Business Park, Eco Way, Dunscroft DN7 4JJ