Pipe Wall Thickness Calculator for Design Pressure - Rapid Global

Required Wall Thickness — Calculation Sheet

Required Wall Thickness

Minimum pipe body wall for a target design pressure — API TR 5C3

Standard	API TR 5C3
Method	Barlow equation (solved for t)
Applies to	Pipe body, zero axial load

Inputs

Grade API 5CT grade you’re specifying. Choose Custom if you need to enter a non-standard or mill-specific yield value. Minimum yield strength, Yp (psi) Auto-fills from grade (API minimum). Replace with the actual value from the mill test report if you have it. Outside diameter, D (in) Pick a standard API 5CT nominal OD, or choose “Custom OD” and type your own value below. Target design pressure, P (psi) The internal yield (burst) pressure you need the pipe body to hold. API wall factor API TR 5C3 uses 0.875 for the standard minimum-wall design case (accounts for the −12.5% manufacturing tolerance) — the sizing default here. Use 1.0 only if you separately intend to apply that tolerance elsewhere.

Units

Result

—

t = (P × D) ÷ (factor × 2 × Yp)

—

Grade	—
Yp (yield strength)	—
D (outside diameter)	—
P (target design pressure)	—
API wall factor	—
Result — required wall thickness	—

Reference & methodology

Standard: API TR 5C3 (formerly API Bulletin 5C3), equivalent methodology to ISO 10400 — this is the same Barlow-equation basis as our Internal Yield (Burst) Pressure calculator, solved for wall thickness instead of pressure.

Formula basis: t = (P × D) ÷ (factor × 2 × Yp). The default wall factor of 0.875 applies API TR 5C3’s standard minimum-wall design case (the −12.5% manufacturing tolerance permitted under API 5CT), so the result is a genuine minimum design wall, not just a nominal-wall screening figure.

Scope and limitations: This sizes the pipe body for internal pressure only — it does not account for collapse (external pressure), combined loading (axial tension/compression, bending), temperature derating, or connection pressure rating. The result is a theoretical minimum; round up to the nearest wall thickness your supplier actually stocks, and re-check that real wall against the burst and collapse calculators.

For preliminary screening only. Not a substitute for a full triaxial (von Mises) load-case analysis or a certified engineering assessment.

Want the worked example and why the wall factor matters here? Read Sizing Pipe Wall Thickness for a Target Design Pressure.

Need help selecting pipe, or a full design case? Talk to an engineer