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.