Pressure Vessel Thickness Calculator

1. Definition

A Pressure Vessel Thickness Calculator determines the minimum required wall thickness of a cylindrical pressure vessel subjected to internal pressure. The calculation follows the classical thin-wall formulation used in ASME Section VIII Division 1 for preliminary design.
It considers internal pressure, vessel diameter, allowable stress, and weld joint efficiency.

2. Background Theory

Pressure vessels operate under internal pressure, which generates circumferential (hoop) stress. For a cylindrical vessel, the primary stress is:

Where:

• P = internal pressure

• D = internal diameter

• t = wall thickness

ASME uses a rearranged form to compute required thickness:

ASME Section VIII Div. 1 (Thin-Wall) Formula:

Where:

• S = allowable stress of the material

• E = weld efficiency (0.6–1.0 depending on radiography)

This formula applies to internal pressure for a cylindrical shell and is widely used in pressure vessel manufacturing, refinery equipment, boilers, reactors, and storage vessels.

3. How the Calculator Works

The calculator performs four engineering steps:

Step 1 — User Inputs

• Internal pressure (MPa)

• Vessel internal diameter (mm)

• Allowable stress (MPa)

• Weld joint efficiency (0–1)

Step 2 — Converts units (if needed)

MPa is directly compatible with N/mm², so the formula uses consistent units.

Step 3 — Computes required thickness

Using the ASME-like thin-wall formula.

Step 4 — Displays result

• Required shell thickness (mm)

• Based on internal pressure loading

• Suitable for preliminary sizing

This calculator gives a first-pass engineering estimate, typically followed by:

• corrosion allowance

• fabrication tolerance

• code checks (UG-16, UG-27)

• fatigue analysis (if needed)