Penstock Wall Thickness & Stress Check

Thin-walled penstock under internal design pressure (static + surge). SI units: m, mm, MPa.

1. Design Pressure

Use either maximum head (Hmax) or direct internal pressure P.
Includes static head + surge allowance.
Default 1000 kg/m³.
Default 9.81 m/s².
Gauge pressure at penstock location.

2. Penstock Geometry

Use internal diameter. For thin walls, Dmean ≈ Di.
Existing / trial thickness to be checked.
Added to minimum required thickness.

3. Material & Allowables

Nominal yield strength of penstock steel.
Often 0.5–0.6 × fy depending on code.
Full-strength weld ≈ 1.0. Poorer joints < 1.0.

Thin-walled cylinder formulas are used. For thick pipes or specific design codes (e.g. ASME, EN), refer to those standards directly.