12. Re-tighten loosened nuts and proceed with torquing of the bolts according to PSI diagram, to 10-15% of specified torque. Remove drift pins and replace with bolts, nuts and washers, tightened to the same values as others in place.
13. Repeat torque sequence, increasing to 50% of balance.
14. Repeat tightening to final torque.
15. Optional – it is always a good policy to go completely around flange checking bolt to bolt for proper torque, particularly on large diameter piping systems.
16. All the above should be done with torque wrenches (mechanical and hydraulic) or with a stud tension measuring device.
17. PSI suggests sealing gaskets are not to be reinstalled or reused.

Always wear appropriate safety equipment!
Important: Check gasket for flange type on which to be used (ie). Slip or weld-neck etc. if in doubt do not install, consult Allied Corrosion Industries, Inc.

To provide even sealing pressure on a flange gasket it is recommended that the bolts be “snugged” up in the sequence shown on chart until the flange faces are in contact with the gasket. After the flange faces are in contact with the gasket firmly tighten the bolts in the same sequence. Note: Although this diagram shows 24 bolts, the same basic procedure should be used with flanges having more or less bolts. When installing gaskets made of compressible dielectric material and tightened cold; “hot flow” of the gasket material may occur under operating conditions, resulting in loss of bolt pressure. It is advisable therefore, to re-tighten bolts after operating temperature has been reached — preferably at zero line pressure and ambient temperature. Under no circumstances should the system be allowed to return to operating temperature after the initial cycling to ambient temperature without checking and re-tightening bolts where needed.