Wrought Washer Manufacturing Inc, a washer manufacturer in North America, has solidified its position as an industry leader by acquiring TurnaSure and its innovative ViewTite® Direct Tension Indicating (DTI) washer line – bringing even greater precision and reliability to structural bolting applications worldwide.
The development of DTIs has its roots in the shift from hot riveted steel structures to high strength bolted connections. In the 1950s, researchers at the University of Illinois, led by Professor William Munce, studied dismantled riveted bridge connections and noticed that the shrinkage of cooling rivets exerted a friction grip on steel beams. With the advent of high strength steels, bolts could be tensioned to extremely high clamp loads, leading to the introduction of high strength friction grip (HSFG) bolts, standardised under ASTM A325 and the higher load ASTM A490.
However, engineers soon realised that relying on torque measurement to determine bolt tension was highly unreliable due to variations in friction at the bolt threads and nut face. Enter Max Turner, OBE, a former motor racing pit mechanic, who understood firsthand the limitations of torque-based measurements. While working in the fastener industry in Sheffield, UK, he pioneered a solution – by incorporating specially designed arches into a steel washer, he created a method to measure actual bolt tension rather than torque. When compressed to a specified gap, these DTIs ensured precise and consistent clamping forces.
Turner’s revolutionary DTIs quickly gained global acceptance, with widespread adoption in the UK and Australia. By the early 1970s, DTIs had become the preferred method for installing HSFG bolts in structural steel buildings. In 1972, Bethlehem Steel licensed the technology for the US market, securing use on most of the nuclear power plants constructed in the USA. By 1984, the company initiated ASTM to publish the first official DTI standard – ASTM F959.
After Bethlehem Steel exited the fastener business in the late 1980s, Max Turner’s son, Jonathan Turner, took over the US operations, working alongside top American fastener engineers to improve DTI designs. Several patents were granted, reducing standard deviation in clamp loads to 2% or better, ensuring unparalleled accuracy. The company later became TurnaSure LLC, who continued to refine and expand the applications of DTIs for modern structural connections.
ViewTite®: The next generation of DTIs
While traditional DTIs provided a reliable method for achieving proper bolt tension, some competitors introduced silicone-based indicators that extruded from pockets during compression. However, these designs were found to be inconsistent, as variations in steel surface conditions, coatings and larger clearance holes could compromise accuracy and reliability.
To address these challenges, TurnaSure developed ViewTite®, a next generation DTI with a durable green elastomer placed in formed tubes on the washer’s top surface. Unlike traditional DTIs, ViewTite® offers several advantages, including superior visual inspection – the green elastomer is only ejected when the bolt reaches the correct tension, providing instant verification for installers. In addition, ViewTite® eliminates the need for additional washers underneath, even when used on oversized or expanded clearance holes. They also offer enhanced durability and visibility, with the elastomer remaining highly visible even in challenging conditions and glows under black light, allowing for easy inspection in low light environments. Finally, ViewTite® offers global compliance and adoption, meeting ASTM F959 and is currently being designed to meet EN 14399-9 standards, making it a universal solution for structural fastening worldwide.
ViewTite® has already proven itself in major infrastructure projects, including the Verrazzano and George Washington Bridges in New York. Recognised for its breakthrough innovation, ViewTite® received the Fastener Innovation Award in 2022. Now, under Wrought Washer’s leadership, ViewTite® is positioned for rapid expansion. With state of the art manufacturing capabilities, including a 225,000 square foot (approximately 21,000m2) production facility, and an extensive US warehousing network, Wrought Washer is increasing availability, including metric sizes for international markets.
With worldwide patent protection, and a focus on continuous innovation, Wrought Washer is ensuring that ViewTite® becomes the industry standard for direct tension indication. As global infrastructure projects demand higher precision and reliability in bolted connections, ViewTite® is set to play a critical role in the future of structural fastening.
Having spent a decade in the fastener industry experiencing every facet – from steel mills, fastener manufacturers, wholesalers, distributors, as well as machinery builders and plating + coating companies, Claire has developed an in-depth knowledge of all things fasteners.
Alongside visiting numerous companies, exhibitions and conferences around the world, Claire has also interviewed high profile figures – focusing on key topics impacting the sector and making sure readers stay up to date with the latest developments within the industry.
