Trust Block (Thrust Block) Calculator

Soil & Safety

Soil Allowable Bearing Capacity (kPa)

Safety Factor

Fitting Type (applies to all pipes below)

Pipe 1

Internal Diameter (mm)

Test Pressure (Bar)

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How This Is Calculated

A pressurized pipe pushes outward wherever flow direction changes or stops - at a bend, a tee branch, or a capped dead-end. The thrust block resists that push by bearing against undisturbed soil.

Key Points:

F = P × A × K — force from pressure, pipe area, and a direction coefficient
K = 2×sin(Δ/2) for elbows (90° → √2, 45° → 0.765); K = 1 for tee/dead-end
Multiple pipes at the same block, same fitting type: forces are simply summed
A_b = (Total F ÷ Soil Bearing Capacity) × Safety Factor

Calculation Steps:

Enter all required parameters
Click "Update Calculation"
Review results and analysis

Formula Variables:

P Test Pressure (Pa)

A Pipe Area (m²)

K Direction Coefficient (-)

F Thrust Force (N)

S Soil Bearing Capacity (N/m²)