69 Tensioning Step 1 Step 2 Step 3 Step 4 General Procedure Step 1 The bolt Tensioner is fitted over the stud Step 2 Hydraulic pressure is applied to the tensioner which then stretches the stud Step 3 The Studs nut is wound down against the joint face Step 4 Pressure is released and the tool removed The bolt behaves like a spring when the pressure is released the bolt is under tension and attempts to contract creating the required clamping force across the joint Read Instruction Manuals Please refer to the product Instruction Sheets for safe use guidelines and detail on the correct set up and operation of the equipment Less than 100 Tensioning Not all applications allow for the simultaneous fit of a tensioning device on each bolt in these cases at least two tensioning pressures are applied This is to account for a load loss in those bolts already tensioned as the next sets are tightened The load losses are accounted for in calculation and a higher load is applied to allow the first sets to relax back to the target preload Tensioning Operation Tensioning permits the simultaneous tightening of multiple bolts the tools are connected in sequence via a highpressure hose assembly to a single pump unit This ensures each tool develops the exact same load and provides a uniform clamping force across the joint This is especially important for pressure containing vessels requiring even gasket compression to affect a seal Setup using a 100 tensioning procedure All bolts are tensioned simultaneously Setup using a 50 tensioning procedure Half the bolts are tensioned simultaneously the tools are relocated on the remaining bolts and they are subsequently tensioned Manufacturers rating of pressure and load are maximum safe limits Good practice encourages using only 80 of these ratings