. 2023 Dec 19;16(1):2. doi: 10.3390/polym16010002

Table 16.

The calculation expressions, according to [106,107,109].

BS 7159:1989	ASME Boiler and Pressure Vessel Code, Section X
$p_{e} = \frac{20 \cdot E_{l a m} ({\frac{t_{d}}{D_{i} + 2 \cdot t_{d}})}^{30}}{F_{s}}$	$P_{a} = \frac{K \cdot \frac{E_{r}}{F} \cdot {(\frac{t}{D_{o}})}^{25}}{1 - 0.45 \cdot {(\frac{t}{D_{o}})}^{0.5}}; i f L_{c} > L$ $E_{r}$ = $\sqrt{E_{1} \cdot E_{2}}$ $K = 3.6 - \frac{2 \cdot E_{r}}{E_{1} + E_{2}}$ = $L_{c} = 1.14 \cdot {(1 - v_{1} \cdot v_{2})}^{0.25} \cdot D_{o} \cdot {(\frac{D_{o}}{t})}^{0.5}$

P_a—allowable external pressure; E₁—axial tensile modulus; E₂—hoop tensile modulus; E_r—resultant modulus; F—design factor = 5.0; D_o—outside diameter; L—design length of vessel section (if this were applied to piping, it would normally be the distance between stiffener rings, if used, or between hangers, with 360° contact, or between secondary overlays and other external stiffeners); t—shell structural thickness (0.25 in. minimum); L_c—critical length; P_e—allowable external pressure (bar); E_lam—modulus of elasticity of the laminate (MPa); t_d—design thickness of the reference laminate (mm); D_i—internal diameter (mm); F_s—factor of safety = 4.0.