Casing Collapse Pressure Calculator

Calculate external pressure resistance and collapse safety factors per API 5C3

Casing Properties

Enter casing dimensions and material properties

Mud hydrostatic at casing depth

Backup pressure inside casing

Typical: 1.0 to 1.125 for collapse

API 5C3 Collapse Regimes

  • Yield Strength Collapse (low D/t)
  • Plastic Collapse (medium D/t)
  • Transition Collapse
  • Elastic Collapse (high D/t)

Collapse Analysis Results

Enter casing parameters and click Calculate

Common Casing Collapse Ratings

Size Weight Grade Collapse (psi)
7"26 lb/ftN-805,410
9-5/8"47 lb/ftN-805,310
9-5/8"53.5 lb/ftP-1107,950
13-3/8"68 lb/ftN-803,450

Formula Reference

D/t Ratio Boundaries (API 5C3)

Yield Collapse: D/t < (A-2)^2 + 8(B+C/Yp) / (2(A-2)(B+C/Yp)) Plastic Collapse: Medium D/t range Transition Collapse: Higher D/t range Elastic Collapse: D/t > 2 + B/A / (3*B/A) Where A, B, C, F, G are API 5C3 empirical factors

Collapse Pressure Formulas

Yield Collapse: Pc = 2*Yp * ((D/t-1)/(D/t)^2) Plastic Collapse: Pc = Yp * (A/(D/t) - B) - C Transition Collapse: Pc = Yp * (F/(D/t) - G) Elastic Collapse: Pc = 46.95E6 / ((D/t)(D/t-1)^2)