Hytorc of the US has announced that exhaustive new tests have upheld the bolt load accuracy of the Hytorc Disc.

It says the tests, conducted in Wood Group Engineering’s Aberdeen (UK) facilities, confirmed that the Hytorc Disc met official standards for critical flanges that have a bolt stretch tolerance of ± 10 per cent, while eliminating reaction arm, backup wrench and bolt elongation measurement. 

“Hytorc is now offering them throughout the many UK industries where safe and accurate bolting is a vital necessity,” a company press release said. The discs, which are certified to ASTM A194-01 and ASME SA 194-01, have been patented worldwide.
Any inaccuracy in bolting derives from the fastener. The Hytorc Disc is a flat washer that fits under the regular nut. It is held stationary by the same reaction arm-free tool that turns the nut. The tool is locked on to indents provided for hands-free operating, even on inverted applications. The disc’s threaded segment   engages in the bolt to stop it from turning along with the nut. The threaded segment is machined inside the disc with a common shear section engineered to fail when a given stretch load is applied to it. As the axial pulling force exceeds the pulling force created by torsion, the shear section of the disc is engineered to resist the latter but to break as a result of the former. The friction created between the sheared-off portions and the axial groove assures an axial rise in the segment in opening without turning. Bolt elongation is therefore more precise and torsion-free.

 To keep present side clearances identical, the Hytorc Disc has the same hex as the nut being used. Unless side-clearance is of no concern, Hytorc recommends a round nut to permit disc engagement by the tool. The disc and the nut are machined out of a single forging to guarantee a known bearing face friction. Intermittent calibration assures the accuracy and repeatability required to obtain a more even, circumferential bolt load than currently achievable with torque or tension.

 Hytorc claims it has pioneered a major step in bolting technology. “Human error has been replaced by engineered simplicity, bringing even greater cost-effectiveness, speedier operations, more predictable accuracy, error-free downtime and far greater safety,” a Hytorc spokesman says.

 Hytorc is inviting companies to try out the discs for themselves and is offering 24 discs per plant free of charge. The company will lend the necessary tools.
 As with all Hytorc products there is a 12-month guarantee, free training and full service backup.  Related tools are also available as part of the company’s selected range of hire equipment from its sole UK distribution and service depot in Blyth.