ASME VIII-1

ASME VIII-1 压力容器

压力壳体与元件设计计算

Shell & Head

Per UG-27/28/32/34, compute required thickness of cylindrical shells, formed heads and flat heads.

Calculation Type

Cylinder Internal Pressure (UG-27) Longitudinal stress (UG-27)(c)(2) Cylinder External Pressure (UG-28) Formed Head (UG-32)

Design Pressure P (psi)

Allowable Stress S (psi)

Joint Efficiency E

Inner Diameter D (in)

Corrosion Allowance CA (in)

Shell Length L (in) — for external pressure

UG-27 (Hoop): t = PR/(SE - 0.6P)

UG-28: Uses iterative external pressure method (Appendix 1-8).

UG-32: Ellipsoidal / Hemispherical / Torispherical formulas.

All results for reference only. The user bears sole responsibility for ASME VIII-1 compliance.

Opening Reinforcement

Per UG-36/UG-37/UG-45, check required reinforcement area for shell openings.

Finished Opening Diameter d (in)

Required Shell Thickness tᵣ (in)

Nozzle Nominal Thickness tₙ (in)

Noallowable Stress Sₙ (psi)

Nozzle Interior Radius rₙ (in)

Reinforcement Pad Thickness tₑ (in)

Reinforcement Pad Reinforcing Bar Self-compensating

Area of reinforcement required = d × tᵣ. Available area must meet or exceed this.

Flange Design

Appendix 2 method: compute flange moment and verify combined stress.

Integral Flange (Class I) Loose Flange (Class II)

Gasket Load Diameter G (in)

Small End Hub g₁ (in)

Large End Hub g₀ (in)

Flange Internal Diameter B (in)

Effective Gasket Width b (in)

Gasket Width N (in)

Flange moment M₀ = Hᴳ·hᴳ + Hᵀ·hᵀ + Hᴰ·hᴰ. Computed stress must be under flange allowable stress.

Supports

Per Appendix 11, check leg/lug and skirt support adequacy.

Lug / Leg Support Skirt Support

Total Load (lbs)

Support Plate Thickness (in)

Lug Width (in)

Lug Height (in)

Allowable Stress S (psi)

Lug stress: combined ≤ 0.8·S. Check bearing, bending and weld shear.

Skirt supports: axial + thermal bending stress combined.

Joint Category & Efficiency

Find UW-12 joint efficiency and UG-99 hydrostatic test pressure.

Joint Location Category

Cat A — Longitudinal joints Cat B — Circumferential joints Cat C — Flange-to-shell Cat D — Nozzle-to-shell

Radiographic Examination Level

Full RT (100%) Spot RT No RT

MAWP (psi)

UW-12 Table: E = 1.00 (A+full), 0.85 (B+full), 0.70 (C+full), 0.60 (D+full). Spot RT reduces by 0.05–0.10. No RT reduces further.

Impact Test Exemption (UCS-66)

Determine if carbon/low-alloy steel components are exempt from impact testing.

Material Group (curve)

SA-516 Gr.60 / Gr.70 SA-516 Gr.65 / SA-285 Gr.C SA-204 Grade A / B SA-203 Grade A/B

Actual Thickness (in)

MDMT (°C)

MDMT: the lowest temperature permitted for a given material and thickness per UCS-66 Fig 1.

Hydrostatic & Pneumatic Test Pressure

Per UG-99 and UG-100, compute the test pressure for hydrostatic and pneumatic testing of pressure vessels.

Test Type

Hydrostatic Test (UG-99) Pneumatic Test (UG-100)

MAWP at Test Temperature (psi)

Allowable Stress at Design Temp S_D (psi)

Allowable Stress at Test Temp S_T (psi)

Minimum Yield Strength Sy (psi)

Actual Shell Thickness t (in)

Test Ambient Temp (°F)

UG-99: P = 1.3 · MAWP · min[(S_T/S_D), 6.5]

UG-100: P = 1.1 · MAWP · (S_T / S_D)

Fixed Tubesheet Heat Exchanger (UHX-13)

Per UHX-13, estimate required tubesheet thickness including thermal and pressure stresses.

UHX Configuration

Fixed Tubesheet (a=0.5) Floating Head

Tube Bundle Outer Diameter D_o (in)

Tube Outer Diameter d_t (in)

Tube Wall Thickness t_t (in)

Tube Pitch p_t (in)

Number of Tubes n_t

Shell Side Pressure P_s (psi)

Tube Side Pressure P_t (psi)

Shell Side Design Temp (°F)

Tube Side Design Temp (°F)

Shell Coefficient of Thermal Expansion (°F^-1)

Tube Coefficient of Thermal Expansion (°F^-1)

Shell Elastic Modulus E_s (psi)

Tube Elastic Modulus E_t (psi)

UHX-13.5: Simplified tubesheet bending stress including differential thermal expansion.