The DuraSquirt DTI Single Pass Flange System consists of a numbered set of unique washers that allow the user to install flange bolting in a single pass. Using experimentally determined elastic interaction coefficients, the user fully torques a flange in a single tightening pass while achieving uniform bolt stresses around the flange. The groundbreaking procedure was made possible by determining and compensating for elastic interactions between all bolts within a flange. As bolts within a flange are tightened, the tightening of each individual bolt interacts with other bolts on the flange, causing them to tighten or loosen without nut rotation. By predicting these interactions, a numbered set of indicating washers can be designed such that each bolt is tightened to a defined tension depending upon its location in the tightening pass, resulting in all bolts tightened to the desired target stress after the single pass operation is complete.
Utilizing the DuraSquirt DTI Single Pass Flange System, repeatable and accurate flange bolt installation is achieved 70% faster than ASME PCC-1 Legacy multi-pass cross pattern tightening (results from independent U of H evaluation). With 75% fewer movements by the installers (leading to increased safety), repeatable and accurate tension is achieved with minimal training and limited experience, without relying on inaccurate torque measurements producing consistent, leak-free connections.