Maximizing HDD Tooling Longevity – Inspection, Maintenance and Replacement Tips

Inspecting and maintaining equipment on horizontal directional drilling (HDD) projects is crucial. However, it’s not only the equipment that requires attention. The HDD tooling used downhole also needs regular inspections, service and when necessary, replacement.

Key Influences on HDD Tooling Durability

HDD tooling has no fixed service or replacement intervals. The lifespan of tooling can vary significantly due to factors such as ground conditions, operator experience, steering requirements and drilling fluid practices.

According to Vermeer Cutting Edge product manager Cody Mecham, contractors generally understand that rocky grounds can be harsh on HDD tooling components. However, in certain cases, abrasive materials like sand can have an equal, if not greater, impact on tooling lifespan.

“Sandy loam provides a highly workable and ideal drilling environment. However, if the drill path is not properly lubricated with the right drilling fluid mixture, HDD tooling can wear out prematurely,” Mecham explained. “Crews should still use drilling fluids during bores, even in optimal ground conditions. Without it, there is a risk of premature wear to bits, reamers, housing and drill rods.”

In addition to ground conditions, the operator sitting in the seat of the drill and the bore steering requirements can also impact the life of HDD tooling. Oversteering or attempting to bore faster than ground conditions allow can shorten the lifespan of HDD tooling.

HDD Tooling Inspection Process

To ensure the condition of the HDD tooling downhole, it is crucial to inspect each piece attached to the drill string before and after a pass.

Mecham’s advice: Always apply grease to threaded connections when adding new tooling. Regularly inspect the condition of these threads using a thread gauge.

In addition to regular visual inspections, operators should remain vigilant about changes during a bore that may indicate tooling-related issues. Loss of steerability or changes in rotational torque pressures could be signs of worn tooling.

Typical signs of wear include thinning, cracking, missing tool components and a loss in boring productivity. In some cases, HDD tooling can be serviced or rebuilt. Even so, all HDD tooling needs to be replaced at some point.

Here is an overview of the inspection process for common HDD tooling found at the end of a drill string.

Starter Rod Inspection

When examining starter rods, it is important to check for signs of wear on the collar. A worn collar can make it difficult to handle torque and may eventually lead to breakage. Keep an eye on the section behind the collar for any accumulation of debris over time. It can cause the rod body to narrow, resulting in a phenomenon referred to as hourglassing. If you notice significant hourglassing, consider replacing the starter rod.

Also, pay attention to the loosening required for proper alignment of the starter rod. This involves tightening the rod and gradually loosening it until two flat sides align, allowing the collar to slide smoothly. If there is a gap of more than 1/16 in (1.6 mm) in the connection when aligning the collar, it can cause similar issues as an under-torqued rod, resulting in excessive flexing and eventual cracking of the starter rod. If there is a gap, you should replace the starter rod.

Transmitter Housing Inspection

When inspecting the transmitter housing, check the fluid ports to ensure proper functioning. Verify that the lid and bolts are in good condition. Measure the outside diameter to determine the amount of wear since new. If the transmitter housing has worn off by 1/8 in. or more, it is likely approaching the end of its life.

Another important step is to inspect the threads on the backend and replace the spud if necessary. Over time, the spud can break off as the equipment ages.

It is also crucial to examine the inside of the sonde compartment for cracking or signs of damage. Cracks can propagate and cause issues over time, potentially leading to breakage.

The only components that can be replaced for the transmitter housing are the hardware, lid, water nozzles and on many models, the spud adaptor.

Replace any housing that shows signs of cracking, lost hardfacing or an outside diameter worn beyond the specified limit.

Drill Bit Inspection

To inspect an HDD drill bit, examine its integrity, shape, carbide assets, diameter and the condition of the bit bolts. Begin by checking for any cracks or visible damage on the bit, making sure there are no flaws that could weaken it. Assess the shape of the bit to confirm it is not losing its form or wearing out, as this can affect steering and drilling efficiency. Take note of any wash around the carbide assets and make sure that the wear is not significant enough to risk dropping a button into the hole, as this can impact drilling performance. Verify that the bit has enough material to cut at the required diameter, as a significantly worn-down diameter may hinder steering capabilities. Lastly, inspect the torque of the bit bolts, making sure they are fresh and tight to maintain the reliability of the drill string.

Replace a drill bit when it has significantly worn down, causing the carbide buttons to no longer resemble buttons but instead look like fingers. Additionally, if you observe cracks propagating on the drill bit, it is time for replacement.

Reamer Inspection

With reamers, it is important to check the condition of the threads. If the threads are damaged, remove the spud and replace it with a new one in the adapter. It is crucial to confirm that the cutters, whether shark or rotary cutters are in good shape and that the reamer has sufficient hardfacing.

The end of life for a reamer occurs when the body’s integrity has been compromised. For example, if the teeth have completely worn off after extensive use or the casting has significantly worn down, it is time to retire the tool.

Mecham’s advice: Remember to maintain a built-up hardface and keep the cutters in good condition. Make sure they are flushed and that the ports are clear and undamaged. This is critical to maintaining the reamer’s functionality.

Magen Andrasko is a brand experience specialist with Vermeer Corp.

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