Anchor trucks boost safety by ensuring that service rigs stand tall, and stay that way.
There’s a lot at stake when crews at Anchor King install screw anchors at drilling pads. The calculus is simple: Either embed the four screw anchors firmly enough or the drilling rig could tip over in high winds. Or during a blowout. Or while working stuck pipe. There’s no margin for error.
But equipped with five anchor trucks outfitted by DB Hydraulics, employees at the company approach each job confidently, knowing they have the power to not only set the piles deep enough, but pull-test them to 25,000 ft-lbs.
THE ANCHOR RIGS
The 5-ton, four-wheel-drive flatbed trucks are made by International, Freightliner and Ford, says Andy Davidson, owner of the company based in Red Deer, Alberta, and established in 2005.
Each anchor rig relies on a hydraulic pump made by Commercial Hydraulics. The pump powers both a drive head, which twists the anchors into the ground with up to 8,000 ft-lbs of torque, and a large hydraulic cylinder (or ram) that performs the pull tests. “We want to be sure the anchors won’t let go in the event a rig starts tipping over,” Davidson explains. “As we twist the anchors into the ground, I’m watching to see how tight things are torqueing up. We stop when we reach 8,000 ft-lbs of torque, which is the equivalent of 25,000 ft-lbs of pulling power.”
The drive head rides up and down a truck-mounted mast, which folds down during transport. The mast can accommodate screw anchors up to 12 feet long. A typical screw anchor is between 2 and 3 inches in diameter and features helix-shaped flanges that bite into the soil as they’re driven down. Anchor King uses anchor screws made by Genax Metal Manufacturing in Edmonton.
After the screw anchors pass a pull test, they’re connected to the top of a drilling rig by guide wires. Soil conditions dictate how deep anchors must be embedded, says Davidson, whose company works throughout Alberta.
“Some areas in eastern Alberta have really good clay,” he explains. “We can’t even get a 5-foot starter anchor in all the way. The ground is so tight that we can leave it as is and pass a pull test. But in northern Alberta, which is full of muskeg (swampy, boggy soil), we sometimes have to go down 60 to 80 feet.”
SECTION BY SECTION
The anchor-driving is done in sections. Crews start with a 5-foot-long starter section. If that depth is insufficient, workers attach another section and drive it into the ground until only about a foot of it is still visible above ground. If needed, then another section gets screwed and bolted on. This process continues until the anchor is deep enough to pass a pull test, he says.
Then workers attach a 1/2-inch-diameter steel cable to both the top of the screw anchor and to a hydraulic cylinder on the anchor-truck rig. As the operator monitors a pull-test gauge, the hydraulic cylinder works its way up to exerting the requisite 25,000 ft-lbs of torque, which must be held for three minutes to ensure it’s safely anchored. “We’re basically trying to pull the anchor out of the ground,” Davidson explains.
“As all this is happening, a chart recorder built into the back of the rig is charting the pull, starting at 5,000 pounds and going up to 25,000 pounds,” he continues. “It usually doesn’t take more than a minute and I’m up to 25,000 ft-lbs. If the test fails, then we add another extension to the anchor and push it even deeper.”
BUILT FOR TOUGH JOBS
Is the work dangerous? “I wouldn’t call it that, but you have to be attentive,” Davidson says. “If you keep your eyes and ears open and know what you’re doing, everything should be just fine.” Bypass safety-check valves prevent the rig from over-torqueing and it also features various guards and safety apparatuses to protect the operator, he notes.
“If an anchor gets stopped dead against a rock, your drive head — which attaches with a bolt to the anchor — will shear off the bolt to protect the equipment,” he adds. “But if a bolt shears off, at times it can take off like a bullet, which is why the rig includes a protective shield for the operator.”
The five anchor trucks were spec'd out with wheelbases that are shorter than a typical 5-ton truck to reduce their turning radius and increase maneuverability on congested drilling pads. “They’re little stubby jobs,” Davidson says. “On tight lease locations, you’re working around all kinds of equipment and vehicles and making tight turns, so we need that sharp turning radius. That allows us to work a little faster, too, which customers appreciate.”
The trucks also feature four-wheel drive, which Davidson points out is unusual for a 5-ton truck. But it’s necessary, given the demanding conditions under which they work at remote drilling pads. It’s not unusual to encounter 1 or 2 feet of mud and getting stuck rarely ends well. “You call for a Caterpillar D8 (bulldozer) to pull you out and hope for the best,” he says. “You might come home without a front end.”
Overall, Davidson says his fleet of anchor trucks are tough, reliable workhorses that keep his company productive and profitable. “They’re pretty basic machines,” he says. “They do just one thing and one thing only, but they do it very well. Without them, there wouldn’t be an Anchor King, for sure.”
OWNER: Anchor King, Red Deer, Alberta
MACHINES: Anchor trucks outfitted by DB Hydraulics on 5-ton International, Freightliner and Ford trucks
FUNCTION: Embedding and pressure-testing safety screw anchors
FEATURES: Hydraulic pump made by Commercial Hydraulics; four-wheel drive; drive head that delivers up to 8,000 pounds of ft-lbs; pull-test cylinder that exerts up to 25,000 ft-lbs of torque; screw anchors made by Genax Metal Manufacturing