Calculate the maximum torsional capacity of a solid round valve stem: elastic limit (no permanent deformation), full-section plastic limit, and design allowable torque with safety factor. Includes cross-hole weakening correction and residual-twist control. Formula: τy = Rp0.2 / √3 · Ty = τy · Wp · Tp = (4/3) · Ty
Open Calculator →
Elastic limit (T_y), elastic-plastic core radius c, full plastic limit (T_p = 4/3·T_y), residual twist inverse, and hardening correction options.
ASME BPVC II-D typical (Rp0.2 = 240 MPa) or ASTM A182 acceptance minimum (170 MPa), plus custom Rp0.2 input. Difference up to 41%.
Subtract cross-hole polar moment Jp_net = Jp − (d_h·d)(d²+d_h²)/12 with Kt stress concentration factor (default 2.0).
Allow limited permanent deformation: binary-search inverse of θres = (τy/Gc − T/GJp)·L for given θ_allow.
Default SF = 1.5 design allowable T_allow = T_y / SF, cross-verified with ASME B31.3 S = min(Rm/3.5, 2/3·Rp0.2).
Optional applied torque input triggers instant PASS/FAIL against the design allowable, factoring hole and residual limits.
Input stem outer diameter d and torsion length L. Length affects twist angle and stiffness, not the torque capacity itself.
Choose ASME II-D typical (240/550) or A182 minimum (170/485), or input custom Rp0.2 and shear modulus G.
Specify cross-hole diameter d_h and stress concentration Kt (default 2.0). Set allowed residual twist angle for limited-permanent-deformation design.
Receive T_y elastic limit, T_p full plastic limit, θy twist at yield, and design allowable T_allow with PASS/FAIL check.
Enter your stem geometry and material parameters to get the full torque capacity report.
Open Calculator →