Understanding the Types of Horizontal Directional Drilling Equipment

A rock hammer by Hardrock HDDP

Horizontal directional drilling, also known as HDD, is a type of construction technique. It's used to drill horizontal tunnels under equipment or waterways. Then, a pipe or other type of machinery is placed in the tunnel. Various types of horizontal directional drilling equipment are used for these tasks.


Equipment Comes in Different Sizes

According to All About Pipelines, HDD crossing of a pipeline usually involves drilling a small pilot hole that's about 6 to 8 inches in diameter. Then, machinery is used to enlarge the hole in diameter, making it the size necessary for pipe string pullback. When different sizes are used, various sizes of equipment are necessary. Types of horizontal drilling equipment are available in large diameter, medium diameter, and small diameter. Most systems operate in the same way, so the main difference is simply the diameter of the tunnel that is created using the equipment.


Types of Guiding Systems

Three main types of guiding systems are used to control the drill head.


  • A walk-over locating system utilizes a transmitter located behind the drill head that measures angle, direction, and rotation. This is then transmitted to the person operating the drill with an electromagnetic signal. Then, the machine gives directions to the person in charge of the drill.


  • A wireline location system is another type of guiding system. This system utilizes a wire grid that is laid out and requires a person on the drill to do calculations to determine how the drill should be operated. These systems are accurate, but are prone to human error and are more time-consuming to operate.


  • Lastly, there are gyro-based location systems. This is also known as gyro-steering. Gyro-steering uses a tool that takes measurements of the drill and uses data to perform calculations. Then, an algorithm provides instructions so the drill is steered accurately. These are useful when a wireline system is impossible, such as when horizontal directional drilling equipment is used under a building or waterway. This type of location system is typically used when a casing is needed.


Understanding the different types of horizontal directional drilling equipment is necessary to ensure that you or a company you work with uses the appropriate equipment. Contact Hardrock HDDP today to discuss horizontal directional drilling equipment further.