Walpole Couple's Firm Has Revolutionized Steel Construction

By Chuck Bingaman

            Kristyna Wallace is president/CEO and husband Chris Curven is vice president of Applied Bolting Technology, a twenty-employee business in the woods off Rt. 103 in Bellows Falls, that has cornered the market on a unique way of indicating bolt tightness for building the world’s refineries, bridges, windmills and other large structures.

            The Walpole couple’s firm’s Squirter® DTIs—that’s Direct Tension Indicators—have transformed the old technology for bolting steel girders together into an easier, safer, less expensive and much more reliable process.  And the company is expecting to sell well over 10 million of them by the end of 2009!

            “You’ll find our Squirter DTIs being used in major building projects right now in the Middle East, Alaska, South America and all over the US,” according to Chris Curven, Vice President and Field Bolting Specialist.  “We work with the largest engineering and construction firms that often specify our product to indicate that the proper clamp load has been achieved in their structural steel connections.”

Curven shows tightened bolting assemblies for windmill construction. Looking carefully around the edges of the bolts you can see the orange silicone that indicates that the bolts are tensioned properly. Chuck Bingaman photo.

            DTIs are washer-like rings with bumps punched into them when they are stamped out of steel strips.  When inserted between a nut and the girders or other pieces of metal being bolted together and then tightened, the bumps flatten out to show that things are tightening up.  That technology has been around for a while. 

But every such nut and bolt assembly needs to be checked by inserting a skinny piece of metal called a feeler gauge all around the DTI in spaces between the bumps. Steel erectors have thought they could measure the tension in the coupling by the amount of “torque” or force needed to turn the nut.  But, of course, that really measures how much effort it took to turn the nut, not the eventual tension in the sandwich of nut, bolt, washer and girders, a tension based on how much the bolt actually stretches in the tightening process.  Knowing the tension in the bolt was just right in every case was a costly, sometimes haphazard construction challenge.

            Then along came Applied Bolting eight years ago with its bright—and patented!—idea! 

Director of Quality Assurance John Herr had an inspiration, headed to Aubuchon Hardware in Walpole, and bought some plastic wood and a small Dremel tool.  He thought he might fill the depressions made on the backside of DTIs where the bumps were punched with some flexible material that would be forced out when the bolts were tightened and the bumps flattened. 

After a lot of experimentation—some goo was too soft, some too messy, some too affected by temperature extremes—Herr and his co-workers settled on a silicone concoction, dyed bright orange, that worked just right!  When the tension level hit the minimum requirement for a tight bolt, it flattened the bumps in the washer-like ring and the orange silicone in the backside depressions shot out the little creases running to the edge of the DTI.  Voila!  Perfect tension, regardless of how easy or difficult it was to screw it together.

Equally important, the visual proof of proper tension enabled inspectors to check the tens of thousands of bolts on large projects like bridges in South America, gold mines in Alaska and oil rigs in Abu Dhabi just by looking at them and spotting unsquirted DTIs or loose bolts in a flash.  And, by avoiding having to do over hundreds or thousands of bolt assemblies, building firms avoided costly add-ons. 

Applied Bolting’s Squirter®DTIs so change the procedures on a large steel fabrication job sites that the company sends representatives out to many sites just to train steel workers in using them.  And, where a job site is in Algeria, Abu Dhabi or South America, where many languages make job-site or classroom instruction difficult, the visual cue to a properly tightened nut and bolt has proven even more valuable.

From initial production of Squirters where the silicone was inserted by hand with syringes, Applied Bolting has created its own robotic assembling systems that can turn out thousands of precisely filled Squirter®DTIs per hour.  Travis Congdon, Manager of Squirter Manufacturing and Process Improvement, has adapted robotic filling equipment and bread proofing ovens from the restaurant industry to help the silicone cure at the proper rate for perfect consistency.  And, he has built sound baffling walls to contain the roar of the machinery.

Amy Millette runs one of the robotic SquirterDTI filling machines for Applied Bolting. Chuck Bingaman photo.

Started by Canadian Wayne Wallace, Applied Bolting was enticed to Ludlow, Vermont originally by then Governor Howard Dean in 1994.  Applied Bolting moved to its own building in Bellows Falls in 2001.  Wallace’s daughter, Kristyn, who moved in to help her dad in the business after college, and is now President/CEO. 

“We run a company without much of a hierarchy,” says Kristyn.  "We’re all working together, and we want a good environment for all of our people to work in.  Family matters come first, and we believe in full benefits for employees.”

“2009 will be our largest year ever,” adds Curven, “and we’re looking for even more growth, especially in the wind energy market as more and more projects get built.”  See www.appliedbolting.com for further information on the company.

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