Stem head extrusion stress: σZY = M1 / (0.12·(DT²−a²)·h1) where M1 = MM+MC, with API 6D safety factor check.
Open Calculator →
Extrusion at stem head insertion against actuator drive surfaces.
Uses ball seal plus bearing friction torque MM+MC.
Effective extrusion area 0.12·(DT²−a²)·h1.
Allowable 210 MPa for AISI 4140 contact surface.
Safety factor λ < 0.67 per API 6D clause 7.20.
Instant PASS/FAIL with margin.
Enter MM and MC from torque module.
Head thickness, diameter, insertion depth.
Set allowable extrusion stress.
Check stress and safety factor.
Enter your design parameters and get instant verification results.
Open Calculator →