Horizontal directional drilling (HDD) involves creating a pilot bore, pre-reaming that bore and performing pullback operations. HDD pipe pullback might be the most important step of the process since it involves installing the pipe as intended to complete the project.
As a driller or contractor, planning is crucial — especially if you want to be efficient. There are a lot of factors that go into pullback, along with notable risks, and time-consuming repercussions for wrong decisions. Streamlining all processes and options for changing the setup can have serious efficiency gains in production. Direct pullback is one of the methods to gain some efficiency.
In a standard reaming situation, an HDD crew would need to remove drill head from the housing and assemble a backreamer configuration to attach in its place for reaming out the bore and widening the hole.
When doing so, there are several considerations that need to be taken such as connection types from the drill string to the reamer, thread connections from the reamer to the pulling eye, or even swivel types for the product. Direct pullback is a method of installing the utility without taking the drill head assembly off – making for a much faster operation. Most often, direct pullback is thought of for installing single, small ducts or cables. But with the right direct pullback attachments, a hole can actually be “reamed” up to 12 in. using the same drill head used to create the pilot bore — which is much faster than the standard reaming. But fast means nothing without strength and efficiency, so there are a few options on the market that offer turnkey solutions for the direct pullback method.
The following are components of direct pullback solutions:
Direct Pullback Attachments
Since you don’t have to remove the drill head to install a reamer, direct pullback attachments are component pieces that attach onto the already-connected transmitter housing and allow you to perform HDD pipe pullback soon after completing the pilot bore. These pullback tools attach directly to the bit or blade. One thing to watch out for is how the pullback attachment is designed and whether or not it is manufactured to hold a swivel in line with the rotation. This will eliminate oblong rotation or unnecessary wear on the tooling due to flopping around.
What is the difference between a standard transmitter housing and a direct pullback enabled housing? Well, the direct pullback enable transmitter housing is effectively a transmitter housing that turns into a backreamer. There is typically more hardfacing or protective surfacing that has been applied to the housing to allow it to stand up to greater wear and tear on pullback. The transmitter housing will also have bolt holes and/or connection surfaces to mount cutters that transition the housing into a reamer-style cutting tool. One thing to keep an eye out for is fluid ports availability. Pullback requires a boost of fluid flow to keep the hole lubricated and the cuttings flowing out of the hole perfectly in tight pullback situations. If the housing does not have an integrated fluid-boosting port integrated for pullback, it will be necessary to add an adapter with it for direct pullback.
Direct Pullback Cutter Blocks
Working with direct pullback housings, cutters that comes mounted on blocks transform your housing into a reamer and allow it to cut with greater aggression. The cutter block designs vary, but you’ll want to choose one that mimics the cutting pattern you would normally choose in a standard reaming situation for the current ground conditions. The beauty with direct pullback cutter blocks is they usually only require small tools for installation, such as Allen wrenches, rather trying to connect up large reamers that are heavy and labor intensive.
Fluid Boosting Adapters
As mentioned earlier, you need more fluid than what a normal housing nozzle can provide when enlarging a hole. That’s why direct pullback housings should come with added ports for pullback. Usually you can simply remove the plug and replace it with a port that allows mudflow. If the housing does not have this already integrated into the design. Try adding an additional adapter that give the mud a boost in front of the reaming action and you’ll have plenty of flow to carry out all the cuttings.
Benefits of Direct Pullback
Direct pullback makes it so you don’t have to haul a ton of equipment into a pit just to install a reamer for HDD pipe pullback operations. This cuts down on time, environmental impact and safety risks. While the ability to ream only up to a 12-in. hole isn’t right for every job, it’s perfect for installing service lines to homes and businesses, or any job that involves pulling fiber. But for smaller diameter jobs direct pullback dramatically increases efficiency and accuracy, limiting the potential for mistakes and damage — and maximizing profits in the process.