Unbalanced Pressure Thrust · Anchor / Thrust-Block Sizing

Pipeline Thrust Calculator

Dead end: F = P·A₁ | Tee branch: F = P·A_b
Bend: F = 2·P·A₁·sin(θ/2)

Pipe size DN

Area is estimated from the nominal diameter. Use "Custom diameter" for the actual bore or gasket seat diameter.

Pressure

Thrust blocks are normally sized for the test pressure, not the operating pressure.

Tee — branch size DN_b

Only used for the tee row. Thrust acts along the branch axis: F = P·A_b (area of the branch, not the run).

Safety factor (applied to anchor force)

Required anchor / thrust-block capacity = thrust × SF. A value of 1.5 is common.

Pressure P–

Diameter D–

Area A–

Base force P·A–

Bend thrust · resultant acts outward along the bisector θ = 90° → F = – kN

Deflection angle θ 90.0°

Thrust & required anchor force
Fitting / location	Thrust F (kN)	≈ kgf	Anchor ×SF (kN)

Pump nozzle check · unrestrained pressure thrust vs allowable flange load

Flange DN (mm) Pressure (bar) Allowable F_sum (kN) SUCTION DISCHARGE

Flange	DN	Unrestrained thrust P·A (kN)	Allowable F_sum (kN)	Ratio	Verdict

Enter the allowable flange load (vector sum F_sum) from the pump manufacturer's datasheet — ISO 5199 Annex B or API 610 tables — using the family-coefficient / material-adjusted values where applicable. The unrestrained thrust applies ONLY if an untied expansion joint / rubber bellows sits at the flange; with tied joints or rigid piping + anchors, P·A never reaches the nozzle and the check reverts to a piping stress analysis (weight + thermal) against the same allowables. Ratio 1.0–1.4 may be acceptable only via the ISO 5199 B.4.4 compensation formula (inlet + outlet combined ≤ 2). EJMA effective area of a bellows is 15–30% larger than the DN bore, so real bellows thrusts exceed the values shown.