Q. Flange Assembly with Bolt Tensioning?

Measure the free length of the bolts ultrasonically. This must be done prior to applying any load to the bolt.

Install bolts on the bottom half of the flange. The bolts must extend one to one and a half bolt diameters from the face of the nut on the side to be tensioned.

Install the gasket on the flange surface to be sealed. The gasket shall be located centrally in the flange assembly. The gasket shall not be forced into position.

Bring the opposing flange into contact with the gasket.

Assemble Hydraulic Bolt Tensioners on the first set of bolts in the pattern (50% of the bolts).

Pressurize the tensioners to the first pass pump setting. Turn the nuts down against the flange face.

Release the pressure after the required pressure is reached and the nuts have been turned down against the joint face.

Transfer the Hydraulic Bolt Tensioners to the second set of bolts in the pattern.

Measure the residual stress in the bolts ultrasonically.

Following hydrotest, complete a check of the bolt stress levels in 5% of the bolts on any flanges sized NPS 24 and above, or with pressure ratings Class 900 and above.

Once the tensioning procedure is complete, apply a liberal coating of lubricant to the stud ends protruding from the nuts.