![]() flange faces must be parallel within 1/16" per foot of diameter, and flange bolt holes must be aligned to within 1/8" maximum offset. Check flange alignment ASME B31.3 Process Piping.DO NOT REUSE old gasket, or use MULTIPLE gaskets. Install the new gasket and be sure gasket is properly centered.Hardened washers are recommended in most applications. Lubricate the threads of the bolt or stud, and the surface of the nut face adjacent to the flange or washer.Replace or repair bolts or nuts as necessary. Visually inspect all bolts and nuts for damaged or corroded threads.Clean the flange faces and check for scars the faces must be clean and free of defects (burrs, pits, dents, etc.).The most common cause of leaky gasketed joints is improper installation procedures.īefore beginning a bolting process, the following preliminary steps will avoid future problems. In a flanged connection, all components must be correct to achieve a seal. Set-up using a 100% tensioning procedure. 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. Pressure is released and the tool removed The stud's nut is wound down against the joint face Hydraulic pressure is applied to the tensioner which then stretches the stud The bolt tensioner is fitted over the stud This is especially important for pressure containing vessels requiring even gasket compression to affect a seal. This ensures each tool develops the exact same load and provides a uniform clamping force across the joint. Tensioning permits the simultaneous tightening of multiple bolts the tools are connected in sequence via a high-pressure hose assembly to a single pump unit. The preload depends on Applied Load and Load Loss (load loss factor). Load loss is accounted for in calculation and is added to the preload value to determine the initial Applied Load. Load loss is a loss of bolt elongation depending on factors such as thread deflections, radial expansion of the nut, and embedding of the nut into the contact area of the joint. * Preload (residual load) = Applied Torque Tensioning can be done using detachable Bolt Tensioners or Hydraulic Nuts. Tensioning requires longer bolts, and a seating area on the assembly around the nut. A uniform load can be applied by tensioning multiple studs simultaneously. Massive mechanical effort to create torque is replaced with simple hydraulic pressure. Inaccuracies created through friction are eliminated. Tensioning is the direct axial stretching of the bolt to achieve preload.
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