Blind-plate Thickness Calculator

Minimum inserted blind plate thickness per ASME B31.3 / B16.48

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Calculates the minimum required thickness of an inserted blind plate using the ASME flat-plate formula.

t_m = d × √(3p / (16 × S × E))

Variable definitions:

• d — Inside gasket bore (RF) or gasket pitch diameter (RJ)

• p — Test or design pressure

• S — Allowable stress (Table A-1)

• E — Quality factor (Table A-1A/B)

Default material: ASTM A285 Gr.C (S = 103.4 MPa). Change S for other materials.

Effective diameter: use the unsupported diameter defined by the gasket and joint geometry—not the pipe outside diameter or nominal pipe size.
Governing pressure: check the most severe differential pressure acting on the plate, including the applicable test condition and static head where relevant.
Material basis: select allowable stress S and quality factor E for the actual material, product form, fabrication route, and metal temperature. The defaults are not universal.
Add allowances: the reported t_m is the pressure-design minimum. Add corrosion, erosion, manufacturing tolerance, and any project-specified allowance before selecting nominal plate.
Joint verification: this screen does not evaluate gasket seating, bolt load, flange rotation, deflection, or leak tightness. Verify the complete flanged joint separately.

Input Parameters