Preventing Drill Rig Rollovers

Published On: April 17, 2024By Categories: Safety, Safety Matters

Knowing the procedures to stabilize a rig can decrease the chances of a costly accident.

By Alexandra Walsh

Drill rigs and other heavy specialty equipment for drilling overturn every year, causing injuries, fatalities, and damage to the surrounding jobsites.

The serious risks related to the overturning of drill rigs are often due to inappropriate load distribution and unstable work surfaces, as well as operation of the rotating and moving parts on the machines, which can lead to injuries.

In most situations, rig rollovers are fully preventable when the appropriate precautions are taken.

Contributing Causes

When drill rigs overturn, factors that contribute to these incidents often include poor working platforms and improper use of equipment.

The working subgrade beneath heavy equipment—the working platform—may provide unsuitable support for the equipment and cause a drill rig to overturn. Proper design of working platforms is based on understanding:

  • Maximum surface slope a drill rig can safely travel on or work from
  • Bearing pressures a drill rig will exert
  • Support capability of the subgrade
  • Potential for old utilities and other subsurface irregularities
  • Managing these pressures and slope on a working platform.

Other contributing factors include soft soils, improperly compacted backfills, underground utilities, voids or tanks, as well as movement up and down slopes. It is equally important to verify proper monitoring, maintenance, and repair of the working platform during use.

Site Prep

The first step in preventing drill rig rollovers is to plan ahead of time by scoping out the terrain of the drilling site.

To the extent possible, avoid rough terrain and sites that don’t allow sufficient space for workers to get to and away from the rig and its support equipment.

Avoid situating the rig on sloped ground. It’s always better for the rig to be upgrade from the bore, but sometimes placing the rig downgrade and drilling up is the only choice.

Prior to moving in the drill rig, the site should be adequately cleared and leveled to accommodate the drilling rig and other equipment and supplies and to minimize fire hazards. The jobsite should be on level ground (recommended to be no more than 5% grade) with solidly compacted soil to support the drill rig and additional equipment.

Evaluate the drilling site prior to setting the leveling jacks, especially if the location is near water or saturated, frozen, or loose caving soil. If necessary, build up solid, compacted earth where the jacks will contact the ground.

If it is necessary to drill inside an enclosed area, make certain that exhaust fumes are conducted out of the area. Exhaust fumes can be toxic and some cannot be detected by smell.

Rig Placement

Rig stability is essential for conducting safe drilling operations. Features that assure proper stabilization include use of hydraulic leveling jacks, blocking (or cribbing), wheel chocks, and rig placement or location.

Specific items to consider in safe rig placement include the following:

  • The rig should be backed perpendicular to the slope so at least the rig is level left to right, and the driller’s platform is closer to the ground.
  • The jacks from left to right should be as level as possible to prevent the rig from moving during operation.
  • When setting up drilling fluid discharge, make sure it is channeled away from the rig to avoid soil erosion under the jacks and cribbing.
  • Avoid situating the rig where overhead obstructions such as tree limbs, canopies, overhead power lines, and piping racks create unsafe drilling or tool handling conditions.
  • Be sure to set the emergency brake once the rig has been positioned.

Rig Stabilization Checklist

In addition to the preliminary site inspection and initial rig placement, it’s important to follow a checklist when drilling on sloped or unstable terrain.

  • Wedge the wheels of the rig so they stay in contact with the ground. Wedge the wheels of all support equipment and trailers.
  • Always avoid placing the rig at a right angle, or perpendicular, to the slope.
  • Take into consideration whether the terrain is rocky because the rig might tilt slightly in one direction. Check that the rig’s wheels aren’t resting on loose soil on one side and rock on the other.
  • If there is snow on the ground, be sure it’s not covering any hidden loose soil. The temperature at ground level beneath the snow could be above freezing even though the air temperature may be below freezing. As soon as the rig penetrates the snow, the soil can become mushy and unstable. Bring a snow or scoop shovel to the drill site to access and visibly inspect the soil conditions beneath the snow.
  • If the soil is loose, muddy, sandy loam that could shift with the weight and vibration of the rig during the drilling operation, it could alter the stability of the rig. Find a different location to drill if possible or add wide, thick boards to create a large base for the jacks or  cribbing.
  • Make sure when the mast is raised that it remains vertical. Because of the center of balance, if the mast is at an angle and the rig slips, the center of balance will shift as well.
  • Be certain everything is locked in place, including the mast lock and outrigging locks. Before starting any drilling, check everything twice.
  • As another precaution, right after the drilling starts and again at 5 to 10 feet, stop and double-check everything. If it’s a long drill, check the rig’s stability periodically throughout the operation.
  • In the event the rig is small and operated by someone sitting on the rig, look to make sure they’re using a seat belt. You never want a worker to try to jump clear from a moving piece of equipment. That’s when most injuries occur.
  • Never move the drill rig while the boom is standing vertical. A lot of rollovers occur because the boom is up and the center of gravity is relatively high, which causes a weight shift from the higher center of gravity that can topple a rig over.

After drilling and removing the shaft, breaking down the operation creates another opportunity for something to slip. For example, as the workers demobilize and take out the cribbing, it’s important not to drop the rig back into sandy soil that will make pulling the rig back off the slope hard to do.

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Drill rig rollover accidents can not only cause serious injuries or fatalities, but they can be costly to companies when the drill rig is badly damaged or totaled. That’s why it is critical every employee knows the steps to prevent such accidents and that shortcuts are never taken.


Alexandra Walsh is the vice president of Association Vision, a Washington, D.C.–area communications company. She has extensive experience in management positions with a range of organizations.

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