The Reverse Circulation Hammer

RC hammers are becoming more common tool for water well drillers—and for good reason.

By LaTisha Shipman

The reverse circulation drilling method is gaining significant traction within the water well industry. For a good reason.

Figure 1. Drill cuttings which passed through the piston of a reverse circulation hammer that didn’t damage the hammer.

While RC drilling has been widely utilized in the mining sector for decades, innovations developed for mining and oil and gas applications often find their way into the water well industry as the technology matures.

Compared to more established methods such as down-the-hole (DTH) drilling, RC is still relatively new. Research indicates that the first RC drill rods were developed in Australia during the early 1970s, while the first dedicated RC hammer was not introduced until the 1980s when Art Holte designed his first true RC hammer. Other early RC hammer designs appeared on the market in the early 1990s, more than 40 years behind the DTH hammer as we currently know it.

The reverse circulation hammer performs exceptionally well in unconsolidated formations such as sands, gravels, and softer rock formations—conditions where DTH drilling would typically require a casing advancement system.

Unlike DTH drilling, RC technology was not originally developed as a competing drilling method. Instead, its primary purpose was to improve sample quality in mining applications using rotary drilling techniques. RC is now a staple in the construction industry and foundation market.

Distinct Advantages

When compared to conventional mud rotary drilling, RC offers several notable advantages including faster penetration rates, improved hole cleaning efficiency, and more effective cuttings removal.

The RC system returns drill cuttings through the center of the drill bit and up through the larger internal passage of the hammer. This closed return path contrasts with DTH drilling, where cuttings are transported externally through the annulus between the drill string and borehole wall. As a result, DTH cuttings can become suspended, fall back to the bit face, or in severe cases accumulate to the point of burying the hammer.

Another key advantage of RC drilling is the reduced risk of formation contamination. Because RC chooses to use a closed-loop circulation system, the potential for introducing contaminants into the formation is minimized. The method also reduces the loss of air and drilling fluids into fractures and fissures, thus resulting in less disturbance to the surrounding geology.

As environmental considerations become increasingly important and many projects seek to reduce their carbon footprint, RC drilling is emerging as a more environmentally responsible alternative. In water well applications specifically, RC hammers can handle substantial water volumes without flooding due largely to the larger internal diameter of the piston design.

Advancing Technology

Much like DTH drilling, which has become a standard across numerous sectors of the drilling industry, RC drilling is rapidly establishing itself as an effective solution for water well construction, mineral exploration, and geotechnical investigations. Its versatility and performance in challenging ground conditions continue to drive its adoption across multiple markets.

Significant investment is currently being made in advancing RC technology. Ongoing developments include lightweight drill rod designs, increased penetration rates, improved system efficiency, and integration with emerging exploration technologies.

Given its relatively recent introduction compared to traditional DTH and rotary drilling methods, RC drilling is expected to experience substantial growth over the coming decade.

Although RC is often associated with large-diameter water well applications, particularly municipal wells of 24 inches and larger, the technology is not limited to these projects. Today, RC hammers are available in sizes ranging from 3 to 24 inches, making them well suited for many residential and smaller commercial water well installations.

The reverse circulation hammer performs exceptionally well in unconsolidated formations such as sands, gravels, and softer rock formations—conditions where DTH drilling would typically require a casing advancement system.

Additionally, a variety of conversion kits are available that allow existing drilling rigs to be adapted for RC operations, lowering the barrier to adoption for contractors interested in expanding their capabilities.

I recently had the opportunity to visit Holte Manufacturing and was impressed by its extensive range of specialized drilling tools, including their casing perforator and extractor hammers as well as the company’s casing hammer systems.

What stood out most, though, was its innovative reverse circulation hammer design. I am convinced Art Holte was a genius. His engineering approach resulted in a hammer that is distinctly different from any other RC hammer I have encountered in the market.

During my visit, a Petra customer’s hammer was in the shop for service, providing an opportunity to observe firsthand the size and type of drill cuttings capable of passing through the piston without causing damage to the hammer. The image accompanying this column illustrates this impressive capability and highlights the durability of the design.

Can your hammer do that?

LaTisha Shipman is in sales for Petra Drilling Supply in Texas. She has more than 20 years of experience in the drilling industry with most of that time spent working in manufacturing with DTH hammers and bits. She can be reached at (817) 517-1308 or tisha@petradrillingsupply.com.