ASME PCC-1 / ASME VIII Appendix 2 Bolted Joint Analysis
Auto-filled from gasket type (ASME VIII Table 2-5.1)
Note: Bolt count, diameter, and gasket dimensions are auto-populated from ASME B16.5 flange standards based on selected class and size.
Understand bolted flange joint theory, ASME PCC-1 assembly procedures, gasket selection, and torquing best practices
A flange leakage check verifies that a bolted flange joint has sufficient bolt load to seat the gasket and maintain a seal under operating pressure. Per ASME VIII Appendix 2, the available bolt area must exceed the required bolt area for both seating (Wm2) and operating (Wm1) conditions. The gasket must achieve minimum seating stress (y factor) and maintain compression exceeding m times the operating pressure.
ASME PCC-1 (Guidelines for Pressure Boundary Bolted Flange Joint Assembly) provides procedures for assembling bolted flange joints to achieve leak-free performance. It covers bolt torque targets, tightening sequences (star pattern), gasket selection, and joint assembly best practices. PCC-1 is referenced by refineries and pipeline operators as the standard for flange assembly.
The m factor (maintenance factor) is the ratio of gasket stress to internal pressure required to maintain a seal during operation. The y factor (seating stress) is the minimum gasket stress in psi required to initially seat and conform the gasket to flange face irregularities. These values come from ASME VIII Table 2-5.1. For spiral wound gaskets, m=3.0 and y=10,000 psi. For ring joint gaskets, m=5.5 and y=18,000 psi.
Target bolt torque is calculated using T = K x D x F, where K is the nut factor (0.20 for unlubricated, 0.15 for lubricated), D is the bolt nominal diameter, and F is the target bolt load per bolt. The target bolt load is typically 40-50 ksi stress on the bolt root area for ASTM A193 B7 bolts. ASME PCC-1 provides specific torque tables by bolt size and lubrication condition.