Bolt Tightening – Do’s and Don’ts

Asked by chadtrinh 5 years, 2 months ago | 1 Answers

1 Answer

Normandy 5 years, 2 months ago



  • Full bolt tightening procedures should be available for the flange size and ratings and the bolt material to be worked upon. The procedure will specify the tools and lubricant to be used. If in doubt, consult a Subject Matter Expert.
  • Number the studs and the nuts as an aid to identification and for applying the criss-cross bolt tightening sequence depicted in the following figure.
  • If using a torque wrench, hand-tighten the studbolts with a short wrench first before torquing. Use the criss-cross bolt tightening sequence. Confirm that the torque wrench is still in calibration. If in doubt, ASK.
  • When using a torque wrench, consult the bolt tightening proce­dure to determine the correct torque settings.
  • Do not draw the flange up tight on one or two bolts only. This will cause local gasket crushing or pinching and will ultimately result in a leaking flange.
  • Do not over-tighten bolts and take particular care with small bolts, i.e. those less than 1 inch in diameter.
  • Do not align/draw misaligned pipework spools together using flange bolts without specific agreement from the Mechanical Supervisor.
  • Do not flog - results are variable and indeterminate.