HDD Rig
Although horizontal directional drilling rigs come in very different sizes and power ratings, all of them have three basic functions: – Thrust – Pullback – Rotation Although the industry classifies these machines by their pullback force, what really matters is torque, i.e. rotation capacity. In most successful projects the pull force required is no more than 30% of the rig's capacity; the same cannot be said of the torque required.
Small and medium rigs are very practical in terms of logistics, set-up and operation. They carry their engine, hydraulic pumps and drill rods on board, load and unload the rods automatically from a magazine, run on tracks and can travel over a wide range of terrain. The pump that feeds drilling fluid into the bore is usually mounted on the rig as well. That is why the most commonly chosen rigs are in this class.
Large rigs require a much more serious organisation. Their logistics alone need at least 3 trucks, and depending on the scope of the project this can rise to 7–8. The hydraulic pumps that provide thrust, pullback and rotation and the diesel engines that drive them are too large to be carried on the rig; these units travel in separate containers and are connected to the rig with hydraulic hoses. The rod loading mechanism used on small and medium rigs is replaced by cranes on large rigs. Although tracked models exist, most are designed as truck trailers for ease of use. The high-pressure pump that feeds the drilling fluid into the bore also travels independently in its own container.
Choosing the right HDD rig is one of the most critical decisions that directly determines the success of a project. When planning a project, not only the crossing length and pipe diameter but also the soil type, groundwater level and potential obstacles along the route are taken into account to determine a horizontal directional drilling rig of suitable capacity. Small and medium rigs are preferred for urban, short and medium-distance projects mainly because of their logistical simplicity and manoeuvrability in confined spaces. Large rigs with high torque and pullback capacity, on the other hand, come into play on long-distance, large-diameter HDD crossings under rivers and motorways.
The fact that rig capacity should be assessed on torque rather than pull force is the single most important piece of know-how that separates experienced HDD contractors from amateur operators. When the torque that rotates the drill head against the ground resistance is insufficient, the planned route cannot be reached, no matter how high the rig's pull capacity. That is why at DELTEK we evaluate torque and pullback capacity together, according to the geotechnical survey, when planning the rig and equipment for each project.
Our Istanbul- and Izmir-based fleet includes both small-to-medium and large horizontal directional drilling rigs, allowing us to deliver HDD services at every scale — from short urban fibre-optic and natural gas lines to long river crossings and large-diameter transmission mains. More than 20 years of field experience have shown us again and again that the right rig choice is the most important factor in shortening project time and reducing cost.
Contact the DELTEK engineering team to determine which rig capacity suits your project, to carry out a geotechnical survey and to receive a detailed technical quotation.
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