Maximising productivity with maxi rig maintenance

To maximise output on large and complex horizontal directional drilling (HDD) projects, a proactive approach is best – because maxi HDD infrastructure projects often have aggressive timelines for completion. Equipment care includes practicing good maintenance habits and planning for issues before they occur.

The most common cause of premature wear of parts and components is not addressing minor issues before they escalate. HDD maxi crews need to pay attention to HDD maxi rig parts, such as vice dies, sub savers, drill rod threads, sliding head shafts, gearbox slides, and water swivels. This article details ways crews can care for these wear parts.

Maxi rig vice dies

The maxi rig’s vice is responsible for torqueing and un-torqueing every drill rod going into the ground. Gripping each connection are vice dies, or vice jaws as some in the HDD industry may refer to them. Vice dies start off with small edges, or teeth, to grip the drill rod when making or breaking a connection. Over time, those edges will wear down and can start to slip when torqueing a connection. An improperly torqued connection can negatively impact the entire drilling operation because it can cause premature wear to other maxi rig parts.

Crews need to keep an eye on the condition of the vice dies. Before starting up for the day, crews should inspect the shape of vice dies. If they are becoming dull and round, it’s time to swap them out.

When vice dies wear too long, rods may start to slip, potentially resulting in premature wear to the threads and the drill’s sub saver. Waiting too long can also make the task of swapping out dies more challenging because they will not slide away from the vice box as easily. And if the dies wear too much, they can eventually damage vice boxes.

Crews should keep their maxi rig’s vice dies clean of debris to get the most life out of them. When it is time to change them, crews should consider investing in an extra set of vice boxes. Trying to slide worn-out dies away from the box on the job can be time consuming, but removing the boxes can be as efficient as spinning out a couple of bolts. Many HDD maxi rig crews will swap out both components on the job. Then, they will swap out the dies on the removed vice boxes back at the shop.

HDD maxi rig sub saver

It is vital for crews to keep their sub saver clean of debris to help prevent premature wear. However, excessive debris isn’t the only thing that can impact the operating life of a sub saver. Improperly torqued rod joints, especially when using a tail string, can also adversely affect the conditions of the sub saver. Play in a few joints can cause damage back to the sub saver. It’s a chain reaction. A gap between the shoulders of one connection can cause excessive wear downhole and back to the sub saver. If a crew isn’t getting up to 200 hours of operations consistently from a sub saver, they should look for issues further down on the drill string.

Crews can determine when to replace the sub saver on an HDD maxi rig in the following ways:

Jagged edges or rounded thread profiles indicate that it’s time to swap out sub savers. However, crews shouldn’t just trust their eyes to determine the condition of threads. Instead, they should have a set of thread profile gauges. This will give them a more accurate visual of the sub saver’s condition. Crews should also keep an eye on where the sub saver connects to the drill’s drive chuck. Any play in that joint indicates that the thread locking compound did not set up correctly. The sub saver may need to be pulled off and the process started again if that happens.

Worn threads on an HDD maxi rig can potentially damage the threads on every piece of drill rod they interact with. This can also lead to weaker joint connections up and down the drill string, which could cause a connection to fail downhole.

Crews should do their best to anticipate when it’s time to replace a sub saver by monitoring thread conditions during drilling operations. Since most thread-locking compounds require 12 hours of setup, swapping subs out at the end of the shift is best.

Maxi rig drill rod threads

The sub saver isn’t the only maxi rig part where thread conditions can impact HDD operations. Crews need to keep drill rod threads clean, covered when not in use and greased. Doing so will help achieve the maximum life out of the drill rods.

Over time, threads will wear out, which can cause joint damage to other rods in the process. So, it’s important to recognise when it’s time to retire a drill rod.

Using a thread profile gauge, crews can quickly determine the condition of their drill threads. No gaps should exist between the gauge and the threads being tested. Crews should also look for any jagged edges or cracks in the metal.

Threads that don’t tightly lock together may not maintain torque during operations. This excessive play within a joint can create a weak spot in the drill string and lead to a break downhole.

When removing a rod from the drill string, crews should use a steel brush to clean the threads and remove excessive grease. After that, new grease should be applied, and each end should be capped before placing it back on a rack or the ground.

Maxi rig sliding head shaft

Some maxi rigs have a sliding head shaft with a full-travel vice. It is essential to keep this maxi rig part greased for optimal performance.

Without adequate grease, the sliding head shaft will start to stick during operations. Everything will feel choppy for the operator. Not regularly greasing the sliding head shaft on an HDD maxi rig can result in premature wear and impact joint alignment when adding drill rods. Crews should consult the machine’s maintenance manual for greasing intervals.

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