The Moyes water-tube boiler patent describes transverse drums, straight tube banks and staggered tube rows. Explore the arrangement and calculate diagonal spacing and clearance between tubes in adjacent rows from their diameter and pitches.
Moyes Tube-Bank Geometry Calculator
Enter declared tube diameter and horizontal and vertical pitches. The worksheet reports stagger offset, adjacent-row diagonal center spacing, surface gap and vertical projection overlap. It does not size, rate or approve a boiler.
Equation Used
- Tube cross-sections are represented as equal circles on a regular staggered grid.
- Alternate rows are offset by one-half the declared same-row pitch.
- The calculator evaluates adjacent-row diagonal geometry only; a negative diagonal gap means that pair of circles overlaps. Same-row spacing and spacing across two rows need separate checks.
- Pressure, temperature, stress, heat transfer, circulation, combustion, materials, fouling, efficiency and operation are excluded.
Tube diameter and row pitches determine the adjacent-row diagonal gap and vertical projection overlap. These geometric results do not establish heat transfer, circulation or pressure capacity.
The patent uses straight direct-circulation tubes and transverse drums
US604777A places transverse water, steam-water and steam drums within the furnace walls. A main bank of straight water tubes runs between front and rear distributing chambers, with an auxiliary bank above it. A vertical baffle bridge wall directs the furnace-gas path and shields the drums from the most intense heat.
The patent drawings provide the detailed arrangement; the illustration here is schematic.
A historical patent-layout study
This page is useful for examining the geometry Moyes claimed: staggered horizontal rows whose vertical projections overlap. It is not a construction, restoration, commissioning or operating guide for any pressure vessel.
Transparent staggered-circle geometry
A positive diagonal gap means the selected pair in adjacent rows does not intersect. It does not check every pair in the bank: same-row and alternate-row separation also matter. A positive vertical overlap reproduces the patent's stated projection condition. Neither value is a thermal, structural or fluid-performance result.
Declared-geometry example
For D=76 mm, Px=130 mm and Py=60 mm, alternate rows are offset 65 mm. Adjacent-row diagonal centers are 88.5 mm apart, leaving a 12.5 mm circle-to-circle gap and 16 mm of vertical projection overlap.
Tube-bank geometry and boiler performance
The staggered grid describes how neighboring tube cross-sections are positioned. A boiler also needs a complete circulation path, suitable pressure parts and a thermal design. None of those requirements can be established from tube diameter and row pitches alone.
Moyes patent questions
Are these historical dimensions?
No. They are declared inputs for exploring the patent's qualitative stagger condition.
Does positive clearance mean the boiler is safe?
No. Positive diagonal clearance checks only a pair of tubes in adjacent rows. It neither checks all tube pairs nor establishes pressure-vessel suitability.
Does this page provide operating advice?
No.
Moyes boiler references
- Laurie M. Moyes, US604777A, Water-Tube Boiler: primary patent text and drawings for the transverse drums, straight-tube banks, staggered rows and baffle bridge wall.
- NIST NCSTAR 1-3E, Physical Properties of Structural Steels: provides material and temperature-dependent properties relevant to thermal expansion; the geometric calculator does not model that expansion.
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