By Jose Mierzejewski
Every driller knows that HDD tooling is subject to an unimaginable amount of stress. It’s a hard fact (pardon the pun), but wear and tear is part of the job. Whether your equipment is taking a pounding from solid rock or being shaved down by the relentless abrasion of sandy loam, the more hours your tools spend underground, the more damage they endure.
So, when’s a good time to replace a tool? When is it a better idea to rebuild? We’ve seen a ton of directional drilling tools in our line of work. Here’s our expert take on what types of tooling you should replace immediately, and what you should repair so you can squeeze out a few more rotations.
Your carbides are on the front line of your drilling operation, in constant contact with ground material. They’re the most likely to show signs of extreme wear and tear. Take note of the appearance of brand new HDD tooling, including measurements and photos. Visually inspect the wear on the carbides after every job. Notice if any carbides are chipped, cracked or misshapen due to wear. Carbides are second-hardest to diamond; your tool bodies (bit, reamer, housing, collar) are not nearly as hard. If carbides are missing or are cracked and about to break off, then the tool body will be absorbing more wear and tear, and you definitely don’t want that.
Depending on your model of bit, your cutters might be removable. In these instances, keep new cutters on hand at every job site, so you can quickly replace worn out teeth with new ones. If your cutters are hard-welded to the tool body, you’ll need to carefully shave them off and weld new cutters in their place.
Once teeth are worn and the body of your bit is taking too much of the brunt force of drilling, it’s time to take your tool in for repair. When the pockets for the teeth are so worn down that new teeth won’t stay in place, consult a professional. Teeth sockets must be precision machined, so the only way to get the best possible repair is to send the tool back to the HDD tooling manufacturer.
Missing carbides on reamers can also become a problem since they put more wear on the body of the tool and reamers aren’t cheap. Watch for wear on the shaft, especially at the front where the cutter blades or reamer body attaches to the shaft. Worn carbides make your reamer work harder, requiring more torque, and might result in your reamer not even cutting to the right diameter. Be careful when welding on new carbides yourself. Welding carbides at an incorrect cutting angle can create extra drag, making your rig work harder and causing pullback to go slower. Incorrect welding could even cause your reamer to cut a larger size.
Used Eagle Claw (left) and Rebuild of Eagle Claw (right)
As part of the Melfred Borzall rebuild program, depending on what condition the tool is in, we offer three levels of repair for our most popular bits, the Eagle Claw and Iron Fist. We can also precisely weld new carbides onto reamers. Manufacturer rebuilds are more effective than DIY solutions and can extend the life of your tool indefinitely. After the rebuild, you’re basically left with a brand-new tool, for about half of what it would cost you to buy a new one.
When it comes to hardfacing, the rule is: more is better (up to a certain point). You don’t want to compromise the chemistry of the steel by putting too much heat to it via hardfacing. This can cause the steel to get too hard, making it vulnerable to breakage. In general, though, hardfacing is your friend. Like a true hero, it stands in between your tools and the punishing ground, sacrificing itself to protect and preserve your valuable directional drilling tools.
For less expensive HDD tooling, hardfacing is a useful band-aid. It won’t protect your tools forever, but it’s a good way to get extra distance out of your tools in the immediate future. However, once wear reaches a certain point, and you’re not getting enough production out of your tool or it looks like it’s going to fail in the middle of a bore, it’s a better idea to replace it. Spending a few hundred dollars to replace a tool on its last legs is a better investment than losing a half day of production trip out your downhole tooling.
In some cases, it may be too late for a rebuild
While serious damage is visible to the naked eye, plenty of types of damage can go unnoticed, even by experienced drillers. It’s a good idea to keep a log book that tracks the distances drilled by your
backreamers, bits, blades, housings and drill rod. Take note of the ground conditions, too. The more data you record, the better analytics you can get out of it. If done correctly, you will be able to predict when items need to be thoroughly inspected, repaired or replaced before something breaks.
When it comes to drill rods, skip the repairs and head straight for replacement. As the guardians of all your downhole tooling, there’s a lot to lose if your drill rod snaps in the middle of a job.
Threads are the most likely to go first. They require such precision machining that it’s smarter to buy new ones than to sink money into trying to re-machine the threads. Inspect your threads closely during each job to make sure they line up correctly and none of the threads appear to be worn. Regularly clean threads and make sure they’re always properly greased. Take a close look at rod shoulders, noticing if they are nice and straight or if the shoulders have mushroomed out. Finally, make sure the rods themselves are straight and haven’t bent due to excessive force. Always rotate your first few rods. They’re the ones that take the most abuse.
Since rods are usually used as a set, if you brake one rod, it’s likely that more will follow. Lots of drillers swap out the whole set of rods when one breaks rather than waiting for each rod to fail individually.
“When should I replace my tool?” The quick and easy answer is: “When the cost to rebuild it is greater than buying a new one.” But you also need to define the true cost of both. Rebuilding might seem cheaper at first, but you have to include purchase and freight costs for parts, your crew’s labor costs, and the amount of money you’re losing by not sending your crew out to a job. On the other hand, if it’s a slow period and your crew is on the clock anyway, it might be a smarter allocation of resources to put them to work repairing damaged equipment.