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NPS 8 class 150 weld-neck flange with a spiral-wound gasket at 150 psi: Appendix 2 bolt loads, hub factors, flange stresses and rigidity

Tool	Bolted Flange Joint
Source	American Society of Mechanical Engineers (2023). ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, Mandatory Appendix 2 (cited; the method of Waters, E. O., Rossheim, D. B., Wesstrom, D. B., and Williams, F. S. G. (1937), Transactions of the ASME, Vol. 59, pp. 161–169); the method checked against Rodabaugh, E. C., O'Hara, F. M., Jr., and Moore, S. E. (1976), FLANGE: A Computer Program for the Analysis of Flanged Joints with Ring-Type Gaskets, ORNL-5035, Appendix A Example 1 and Table A.2.
Level	Professional

Problem

An NPS 8 class 150 weld-neck flange (illustrative B16.5 dimensions: A 13.50 in, bore 7.981 in, t 1.12 in, hub g_0 0.322 in to g_1 0.8545 in over h 2.397 in, bolt circle 11.75 in, eight 3/4-10 UNC bolts) seals a spiral-wound gasket (OD 10.62 in, ID 9.00 in, m 3.0, y 10,000 psi) at 150 psi with SA-193 B7 bolts (25,000 psi) and an SA-105 flange (20,000 psi, E 29 Msi). Find the effective gasket width and reaction diameter, the operating and seating bolt loads and required area against the bolts provided, the flange moments, the K, T, U, Y, Z and F, V, f factors, the hub, radial and tangential stresses at both conditions against the Appendix 2 limits, and the rigidity index.

Inputs to Enter

Integral flange; A 13.5, B 7.981, t 1.12, g_0 0.322, g_1 0.8545, h 2.397, C 11.75 in; flat gasket OD 10.62, ID 9.00 in, m 3.0, y 10,000 psi
8 × 3/4-10 UNC bolts (root area 0.302 in² each), S_b = S_a = 25,000 psi; P = 150 psi; S_fo = S_fa = 20,000 psi, S_n = 17,100 psi (hub welded to pipe), E = 29 Msi

Open the Bolted Flange Joint tool (loaded with this example)

Answers

N = 0.81 in, b_0 = 0.405 in > 1/4 in → b = 0.5 √b_0 = 0.3182 in, G = G_o − 2b = 9.984 in
H = π G² P/4 = 11,742 lb, H_p = 2b π G m P = 8,982 lb, W_m1 = 20,724 lb; W_m2 = π b G y = 99,801 lb; A_m = 3.992 in² (seating governs) against A_b = 2.416 in²: M.S. −0.39, the known shortfall of a B16.5 class 150 flange with a high-seating-stress gasket (the standard rates the flange, UG-44)
W = (A_m + A_b) S_a/2 = 80,101 lb; h_D 1.457, h_T 1.384, h_G 0.883 in; M_o = 24,733 lb-in, M_gs = 70,745 lb-in; B_s = 4.61 in exceeds 2a + 6t/(m + 0.5) = 3.42 in (B_sc = 1.327 if applied)
K = 1.6915: T 1.6288, U 4.2503, Y 3.8678, Z 2.0746; h_0 = 1.6031 in, g_1/g_0 = 2.654, h/h_0 = 1.495: F 0.6420, V 0.07503, f = 1 (the computed ratio −0.015 is below 1), e 0.4005 /in, d 574.6 in³, L 1.0385
Operating: S_H 4,087, S_R 3,802, S_T 1,669 psi, averages 3,944 / 2,878 psi; seating: S_H 11,690, S_R 10,874, S_T 4,773 psi, averages 11,282 / 8,231 psi; all within 1.5 S_f and S_f (governing M.S. +4.07 operating, +0.77 seating); J = 0.064 / 0.184 (rotation about 0.02° / 0.06°)

Notes

The tool's default inputs are this joint; press Submit. The B16.5 dimensions are illustrative values flagged on the form (the standard is cited only). The method itself is checked by test_bolted_flange_joint.php against the printed Example 1 of ORNL-5035 (60 in API 605 300 lb flange: every load, moment and flange stress of Table A.2 reproduced to the printed digits or within 0.02 %), Table 3 of ORNL/Sub/2913-3, the Code's limiting factor values, a scipy solution of Waters' tapered hub and twenty seeded flanges against an independent numpy implementation.