This revision keeps the recognizable horizontal cylindrical shell and external heat path while limiting the worksheet to exact, pressure-free circular-segment geometry. It does not predict steam output or give boiler operating, inspection or test instructions.
Horizontal Boiler-Shell Fill Geometry Explorer
Enter internal diameter, straight internal length and declared liquid depth. The worksheet calculates flat-ended cylinder, liquid-segment, vapor-space and liquid-surface-chord geometry only.
Equation Used
- Internal cross-section is circular and constant along the entered straight length.
- The axis is horizontal and both idealized ends are flat.
- Declared liquid depth h is measured vertically from the internal bottom, from 0 to diameter D.
- Vapor-space geometry is the gross cylinder volume minus liquid-segment volume.
- Animation heat and vapor markers are qualitative and are not a thermodynamic simulation.
- Heads, nozzles, domes, fittings, tubes, internals, shell thickness, pressure, temperature, stress, firing, evaporation, efficiency, inspection, testing and operation are excluded.
Removes unsupported steam-output, firing, hydro-test, inspection, maintenance and recommissioning advice and retains exact pressure-free horizontal-cylinder segment geometry only.
A plain horizontal shell separates liquid and upper space geometrically
The defining geometry is a horizontal cylinder. In an ideal circular end view, a horizontal liquid surface cuts a circular segment from the lower portion; extending that segment through the straight length gives its volume.
The external fire and rising markers in the animation are qualitative context only. They do not solve heat transfer, boiling, circulation or steam conditions.
The worksheet is useful for geometric comparison only
It can compare gross, lower-segment and upper-remainder volumes for declared dimensions. Real boiler work is governed by the applicable jurisdiction, code, original design documentation and authorized inspection. ASME BPVC contains separate construction, care, operation and inspection provisions; this page replaces none of them.
Use the exact circular-segment area
The National Bureau of Standards published horizontal cylindrical tank gallonage from circular-segment coefficients, and New Jersey DEP gives the corresponding stationary-volume geometry. Multiplying segment area by the straight internal length gives idealized liquid volume.
A declared shell-geometry example
For a 1.80 m internal diameter and 6.0 m straight length filled to 65% of diameter, gross flat-ended cylinder volume is 15.268 m³, liquid-segment volume is 10.506 m³, upper remainder is 4.762 m³ and the liquid-surface chord is 1.717 m.
Geometric upper space is not operating steam capacity
Real internal volume can differ because of formed heads, domes, nozzles, tubes, fittings, stays, deposits and measured wall condition. More importantly, geometry alone says nothing about pressure integrity, permissible level, firing, evaporation, efficiency or operation.
The prior universal hydro-test multiplier, firing bands, steam-output predictions, material selections, thickness and temperature claims, inspection thresholds, maintenance procedures, troubleshooting, recommissioning advice and fabricated field cases are removed. Hydrostatic testing itself carries hazards and requires an authorized procedure and responsible supervision.
Horizontal-shell geometry questions
Is 65% depth equal to 65% volume?
No. Circular-segment geometry is nonlinear away from half-full.
Does upper-remainder volume equal usable steam capacity?
No. It is geometry only.
Does this calculate boiler output or efficiency?
No.
Can it specify test pressure or operating level?
No.
Horizontal-cylinder and boiler-scope references
- US National Bureau of Standards Circular 416: horizontal cylindrical tanks, partial depths and circular-segment coefficients.
- New Jersey DEP Field Sampling Procedures Manual, Chapter 6: stationary liquid volume in a partially filled horizontal cylinder.
- ASME 2025 Boiler and Pressure Vessel Code overview: separate construction, operation, maintenance and inspection scope for boilers.
- National Board, A Safe Approach for Hydrostatic Testing: testing responsibility, controlled procedures and personnel safety.
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