Wall thickness from OD and ID, plus the minimum wall needed for a pressure vessel or tube at a given material yield strength and safety factor.
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Request a Proposal →Wall thickness determines the strength and pressure capacity of tubes, pipes, and hollow components. This calculator computes the actual wall, minimum required wall under internal pressure, and the resulting safety factor.
Thin-wall (Barlow's formula) applies when wall thickness is less than 10% of the inner radius. It assumes uniform stress through the wall. Thick-wall (Lame formula) is needed for hydraulic cylinders and high-pressure vessels where stress varies through the wall — use for wall/radius ratio over 0.1.
4:1 is standard for industrial hydraulics per ISO 4413. Aircraft hydraulics use 4:1 on proof pressure (typically 1.5x working pressure). Test pressure is usually 1.5-2x working pressure. A manifold rated at 210 bar (3000 psi) should withstand 840 bar burst pressure.
The allowable stress in the formula depends on the material yield strength and safety factor. 6061-T6 aluminium (yield 240 MPa) requires thicker walls than 7075-T6 (yield 470 MPa) for the same pressure. Stainless 316 at 200 degrees C has only 70% of its room-temperature strength — derate for elevated temperature.
Enter the outer diameter, inner diameter, internal pressure (if applicable), and material allowable stress. The calculator shows wall thickness, minimum required wall under pressure, and the safety factor. For hydraulic applications, maintain at least 4:1 safety factor on ultimate tensile strength.
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