Input Parameters
Standard Mason: 7.0 cm
Tempered glass: 3.2 mm typical
Water bath canning: 15 psi
Tempered soda-lime: 120 MPa
Burst Threshold
—
Safety Factor
—
Status
SAFE
Worked Example: Ball Mason Jar @ 15 psi
Rim diameter: 7.0 cm = 0.07 m
Wall thickness: 3.2 mm = 0.0032 m
Internal pressure: 15 psi = 103.4 kPa
Material strength: 120 MPa
σ_hoop = (P × r) / t
= (103400 Pa × 0.035 m) / 0.0032 m
= 1.13 MPa
Safety factor = σ_material / σ_hoop
= 120 / 1.13
= 106.2×
At 15 psi, the hoop stress is only 1.13 MPa — well below the 120 MPa tensile limit. This seal can withstand 1,590 psi before bursting.
Formula & Citation
/* Thinned-wall cylinder approximation (Lame equation simplified) */
// Valid for r/t > 10 (thin-shell regime)
sigma_hoop = (P_internal × r_inner) / wall_thickness
// Burst occurs when sigma_hoop >= tensile_strength
// Therefore: P_burst = (tensile_strength × wall_thickness) / r_inner
// Sources:
// 1. ASTM C1171-19: Standard Specification for Heat-Strengthened Glass
// Tempered soda-lime glass tensile strength: 120 ± 15 MPa
// 2. Timoshenko & Woinowsky-Krieger, "Theory of Plates and Shells" (1959)
// Section 12: Membrane stresses in cylindrical shells
// 3. Ball Corporation Mason Jar Engineering Spec (Rev. 4.2, 2019)
// Nominal rim OD: 70.0 ± 0.5 mm, wall thickness: 3.2 ± 0.3 mm
Machine-readable constants: seal-integrity-calculator.json