// Free Engineering Tool

External Pressure & Collapse Calculator

Calculate elastic and plastic collapse pressures for cylindrical shells subject to external pressure using the Windenburg-Trilling formula and DNV interaction approach, including water depth pressure conversion and geometric ratio checks.

Calculate the elastic and plastic collapse pressures for cylindrical shells under external pressure — vacuum vessels, jacketed vessels, buried pipework and subsea applications. Uses the Windenburg-Trilling elastic collapse formula with a DNV-derived ovality interaction for combined failure. Allowable pressures per ASME VIII Div.1, PD 5500 and EN 13445-3 (all apply a safety factor of 3.0 on critical elastic collapse pressure).

Optional — Convert Depth to Pressure

Waterdiepte (m)

Medium

Uitwendige druk op diepte

— bar

Geometry

Quick-Select NPS (sets Do & t)

Outside Diameter D_o (mm)

Wanddikte t (mm)

Ongesteunde lengte L (mm)

Material & Loading

Materiaal

Elasticiteitsmodulus E (GPa)

Yield Strength σ_y (MPa)

Dwarscontractiecoëfficiënt ν

Ontwerp uitwendige druk (bar)

Initiële ovaliteit f₀ (%)

Corrosietoeslag c (mm)

Geometrische verhoudingen

ASME VIII / PD 5500 / EN 13445

D_o/t (Diameter Ratio)

—

L/D_o (Slenderness)

—

Net Wall Thickness

—

mm (after corr. allow.)

Mean Diameter D_m

—

Bezwijkdrukken

Windenburg-Trilling · DNV Interaction Formula

Elastic Collapse P_e

—

bar

Elastic Collapse — Long Cylinder

—

bar

Yield/Plastic Collapse P_y

—

bar

Critical Collapse P_coll (with ovality)

—

bar

Allowable Ext. Pressure P_a (SF = 3.0)

—

bar

Safety Factor on P_des

—

× P_des

Max. Unsupported Length L_max

—

Failure Mode

—

Geschiktheid standaard schedule

ASME B36.10M — Voor ingevoerde D_o

Enter geometry and material to generate table.

    Elastic collapse: Windenburg-Trilling formula (1934). Plastic collapse: thin-wall yield. Combined: DNV interaction formula. Allowable: Pcoll/3.0 (ASME VIII Div.1 Clause UG-28 / PD 5500 Appendix B / EN 13445 Annex B approach). Reference only — verify to applicable code at design temperature.
    
  

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