Bolt Tensioning / Torquing

Bolt Tensioning/Torquing Services

Hydraulic Tensioning is the finest method available to achieve proper bolt loading in critical connections. Traditional methods of torque tightening large bolts and studs are inefficient and dangerous. Upto 90% of the energy required to tighten a nut is wasted in overcoming friction. Accurate tensioning is difficult, if not impossible. Variation in the physical strength of fitters is one of the major factors affecting accurate bolt tensioning, and whilst torque wrenches can help with this problem, they cannot compensate for frictional variations between nuts, washers and bolting surfaces.

Plant-Tech provides an efficient bolt tensioning service in cases where bolt-up causes problems. Hydraulic tensioning is substantially faster, requires significantly less manpower and delivers a superior result, at less cost. Hydraulic tensioning tools are much smaller and lighter than torque wrenches. They can be quickly and easily moved into a wide range of different positions around the face of the flange. Hydraulic Tensioners apply hydraulic force directly to the bolt, and thus achieve accurate and uniform tension.

However, to give the most accurate residual bolt loading and uniform compression of a joint, the tools are ideally applied in an arrangement where all the bolts can be simultaneously tensioned. In a gasketed flange, a minimum of 50% of the bolts should be tensioned simultaneously. 100% tensioning is achieved where tensioning tools are attached to bolts alternatively on each side of the flange. 100% tensioning combines the greatest accuracy with the shortest assembly times.

Hydraulic hoses connect all of the tools to the air driven hydraulic pump unit enabling every bolt to be tensioned simultaneously. This ensures that:

  • The gasket is compressed evenly throughout the operation.
  • All bolts have the same accurate residual bolt load.

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