ASME PCC-1

Covers — assembly guidelines for pressure-boundary bolted flange joints: target bolt-load determination, tightening pattern and sequence, tool selection (torque/tension), joint-assembly procedures, assembler training/qualification (Appendix A), and leak troubleshooting.

Does NOT cover (exclusions) — the following are governed elsewhere:

• Flange design and rating → ASME B16.5 / B16.47; gasket dimensions → ASME B16.20 / B16.21.
• Bolt/nut material → ASTM A193 / A194 / A320.
• The design bolt load calculation (Appendix O is guidance, not a design code) → the vessel/piping code.

PCC-1 governs how the joint is assembled; the components and their ratings come from the flange, gasket, and bolting standards.

PCC-1 provides good-practice guidance for joint assembly:

• Target Bolt Load — determine and control the assembly bolt load appropriate to the gasket and flange.
• Tightening Sequence — cross (star) pattern, multiple passes, and final rotational passes for uniform load.
• Tools & Calibration — torque or tension tools with verified calibration and friction control.
• Assembler Qualification — training and qualification of personnel (Appendix A) and joint cleanliness/inspection.

ASME PCC-1 is the industry good-practice guide for assembling pressure-boundary bolted flange joints — the activity that, more than any single component, determines whether a flange leaks. It covers the target bolt load, the cross-pattern multi-pass tightening sequence, calibrated tools, and assembler qualification.

Because most flange leaks come from assembly rather than the gasket, PCC-1 is where reliable joints are made: uniform, adequate, controlled bolt load on clean, aligned, correctly gasketed faces. It complements the component standards (B16.5 flanges, B16.20 gaskets, A193/A194 bolting).

Engineering Note: Qualify assemblers and use calibrated, controlled tightening — a joint torqued by feel or in the wrong sequence can leak even with a perfect gasket and correctly rated components.