How to decide on between dual-rod and single-rod HDD models


Twin-rod horizontal directional drills (HDDs) just like the Vermeer D40x55DR S3 and D23x30DR S3 Navigator HDDs symbolize the newest know-how for drilling rock. However as with all new know-how, many HDD contractors could also be questioning: is a dual-rod machine a greater choice than a single-rod machine?

As you might be researching choices for boring rock as effectively as attainable, Tod Michael, product supervisor for trenchless core merchandise, provides the next recommendation: HDD utility contractors who carry out 50 p.c or extra of their bores in soft- to medium-density rock, as much as 24,000 psi (165.5 MPa) compressive energy, ought to completely contemplate investing in a dual-rod HDD. For contractors boring in rock lower than 25 p.c of the time, there’s most likely a extra economical single-rod tooling setup to satisfy their wants.

And for anybody whose rock-boring work falls between these two ranges, different elements must be thought of earlier than deciding if they are going to profit from including a dual-rod machine.

First issues first

Earlier than diving into whether or not or not you need to spend money on a dual-rod machine, you could know a bit bit in regards to the know-how and its benefits for drilling in rock. “Twin-rod methods use two independently managed drill rods – one throughout the different – throughout operation,” defined Michael. “Whereas drilling out the pilot bore, the outer rod offers rotation for steering, whereas the interior rod provides torque to a tri-cone or PDC drill bit. It is a highly effective mixture that delivers optimum downhole reducing motion and steerability. Its footprint is just like its single-rod corresponding mannequin, making it a extra compact choice than different rock drilling options.”

Rock density

One of many first elements to think about earlier than selecting a dual-rod machine is the kind of rock you are working in. “Twin-rod drills are environment friendly in light- and medium-density rocks,” famous Michael. “If persistently above 20,000 psi (137.9 MPa) compressive energy, a contractor could need to think about using a utility drill with an air hammer or a mud motor. Whereas dual-rod machines are able to drilling in exhausting rock, manufacturing may be higher with a kind of two choices.” 

Job web site

For many utility HDD work, small job websites and the power to rapidly arrange and tear down are important to a crew’s working effectivity. “Twin-rod machines can typically be transported on the identical trailer as their comparable single-rod counterpart, are handy to arrange and do not require any extra house,” defined Michael.

So, in case your crews usually carry out a number of drill pictures a day or all through the week, a dual-rod machine has a number of benefits over different rock drilling tech. Nevertheless, a single-rod machine and an air hammer or rock-bit system just like the Vermeer Armor drilling system could also be a extra economical choice in the event you’re not performing rock bores continuously. 

“Contractors want to take a look at their working prices to find out which is the best choice for his or her wants,” stated Michael. “The crew might be able to get a undertaking completed quicker with a dual-rod machine, however it could be extra economical in the long term to take a bit longer and use a single-rod drill with different rock drilling know-how.” 



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