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How to Choose the Right size of Horizontal Directional Drill

Trenchless technology of horizontal directional drill (HDD) is a serious alternative to the traditional open method of laying communications, which is accompanied by digging trenches. HDD machine are actively used for unburdened installation of communications. These systems allow pipelines to be drawn in boreholes created from the earth’s surface along a pre-planned route. This method facilitates the installation of communications in urban areas, under buildings, roads, through water barriers and other obstacles, as well as at intersections with existing utility networks.The effectiveness of this method in conditions of dense urban infrastructure, when overcoming natural or artificial obstacles, is beyond doubt.

The authority of the founders of the technology – the USA – in the field of drilling equipment for HDD is undeniable. The equipment of the famous American company Vermeer is recognized as a standard of quality. Large-scale production of HDD drilling rigs has been established in EU countries. At the same time, manufacturers from Russia, Belarus and China are increasingly entering into competition with American and European firms.

Features and Classification of HDD machine

Horizontal directional drilling is carried out using self-propelled drilling rigs or equipment mounted on a support frame. In Germany, a classification of HDD machine has been developed, including the categories Mini, Midi, Maxi and Mega. Assignment to one category or another depends on the power of the traction force. There is a direct relationship between traction force, diameter and length of the pipeline.

Installation classWhere is it used?Maximum borehole diameter, mmMaximum pipeline length, mTraction force, kNTorque, kN∙m
Mini –small  HDD drilling rigLaying in the city of protective cases for cables or pipelines from polyethylene pipes with a diameter of up to 250 mm300250Up to 100From 1 to 10
Midi -Medium size HDD machineLaying pipelines with a diameter of up to 800 mm in the city or outside the city, including when crossing highways or small water barriers1000750From 100 to 400From 10 to 30
Maxi-Large drilling rigsLaying pipelines with a diameter of up to 1250 mm and a length of more than 700 m18001000From 400 to 2500From 30 to 100
MegaLaying of main pipelines with a diameter of up to 1800 mm and a length of over 1000 m20002000Over 2500Over 100

Drilling equipment of the Mini or Midi class, partly Maxi, is usually a self-propelled device with an operator’s cabin. The running gear is mainly tracked, less often wheeled. Compact and maneuverable Mini class units are convenient when working in very limited space.

15ton HDD machine
15ton directional drilling machine
38ton HDD machine price
38ton HDD machine price

Mega and partly Maxi class drilling equipment, as well as well machines for installation in a mine or well, are mounted on a support frame, which is secured to the ground with anchors. Mega class devices in some cases can be equipped with a chassis.

90ton large HDD machine
90ton large HDD machine

Non-self-propelled directional drilling rigs with high traction force are delivered to the work area by trailer or assembled on site from separate modules transported in containers.

How to choose a HDD drilling rig

When choosing HDD drilling equipment, the type of communications being laid, the length and diameter of the pipeline, and engineering and geological conditions in the construction area are taken into account. The traction force with torque of the equipment must be no less than the calculated values of the gasket, taken with a safety factor. you should be guided by the rule: the traction force must be at least twice the weight of the pipeline being laid.

First of all, you should determine the length of the underground pipelines constructed using this technique. If the laying distance exceeds 100 meters, then HDD rigs should be selected from crawler-mounted installations. As a rule, such a unit must weigh from 5 tons in order to serve as a reliable support when performing work.
The next important criterion is what size pipes this equipment is required for. Having decided what is needed, we find a list of expanders in the characteristics and look at the maximum diameter of the penetration. Along the way, we pay attention to other points:
· engine power (brand, manufacturer);
· fuel consumption;
· developed traction force and torque (the more, the better);
· drilling speed in different gears.
You should pay attention to whether the design includes an automatic rod feeding system, which greatly facilitates the operator’s work and speeds up the process.As for the price, it is also important to take it into account, especially since the cost of some HDD machine installations seems incredibly high. Don’t strive for versatility – define the range of tasks and clear criteria that the equipment must meet. This will limit the list of options, making it easier to choose just one.

Important “little things” that should not be forgotten
If you do not want to spoil the asphalt surface with steel tracks when moving equipment, then choose a vehicle with rubber tracks. This chassis is quite durable, but lighter and more flexible. Be sure to pay attention to the maximum allowable angle for lifting the combine on an inclined ramp (the higher, the better). If this indicator is close to 25 °, then the device will be able to independently drive into (move out) a vehicle trawl.
Are you going to operate the HDD machine in winter? If yes, then be sure to choose equipment equipped with a device for heating the engine and transmission oil. This will make it much easier to start it in cold weather.

Group of soils by drill abilitySafety factor
By traction forceBy torque
I–III (peat, sandy and clayey soils, weak rocks)1.51.2
IV–VI (pebble-crushed stone soils, porous rocks)2.01.35
VII and higher (hard rocky soils)2.51.5


Choosing the right horizontal directional drilling (HDD) is critical to maximizing your crew’s productivity when drilling large diameter holes over long distances. You must ensure that you select a rig that has the proper torque for the ground conditions and the thrust/recoil power to support the weight of the pipe being installed. You should also consider choosing a drill that will provide the most efficient results—from transportation and installation to project completion—job after job.

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