Key requirements from ASME PCC-1 include:
? Tightening in at least three passes: snug, full torque, and a final torque check.
? Using a star or cross pattern for flanges with 4, 8, 12, 16, or 20 bolts.
? Applying lubricant to threads, nut faces, and washer surfaces to achieve consistent friction.
? Controlling torque within ?10% of the target value.
Lubrication is often overlooked but directly affects bolt load accuracy. ASME PCC-1 recommends using anti-seize compounds with a known coefficient of friction. Without proper lubricant, torque-tension relationships become unpredictable, leading to under- or over-tightening and potential joint leakage.
For welding engineers and QC personnel, verifying that flange make-up follows the specified sequence and lubrication is a routine inspection point. A simple check: watch the first pass of tightening. If the operator jumps from bolt to bolt randomly, the joint may fail a hydrotest.
How does your team ensure flange bolt torquing complies with ASME PCC-1?
Source: ASME PCC-1, 2022