| ProjectSample Project — Demonstration Only | Job No.SAMPLE-001 | Client— |
| CalculationPipe Support Spacing Calculator — Maximum Deflection-Limited Span | Calc byPiping Toolset (calc-core) | Checked byUNCHECKED — sample |
| Date2026-07-21 | Rev0 | BasisDeflection-limited support span (beam form) |
4 in FRP process line, 4.5 in OD × 4.0 in ID structural laminate, long-term flexural modulus 1,000,000 psi. Operating load (pipe + contents) 2 lb/in, owner's sag limit 0.5 in, single simply supported span (c = 5/384).
| Flexural modulus E | 1,000,000 | psi |
| Outside diameter OD | 4.5 | in |
| Inside diameter ID | 4.0 | in |
| Uniform load w | 2 | lb/in |
| Deflection limit δ | 0.5 | in |
| Coefficient c (5/384) | 0.0130208 | — |
Mid-span deflection of a uniformly loaded prismatic beam, solved for length:
δ = c · w · L⁴ / (E · I)
L = ( δ · E · I / (c · w) )1/4
I = π/64 · (OD⁴ − ID⁴)
where δ is the allowable mid-span deflection (owner's spec, commonly 0.5 in), E the flexural or elastic modulus at design temperature, w the uniform load per unit length (pipe + contents + insulation), I the section moment of inertia of the bare pipe wall, and c the end-condition coefficient in the deflection equation — 5/384 for a single simply supported span, roughly 1/185 for the interior spans of a continuous equal-span run. Because L varies as the fourth root, span is insensitive to load and modulus: quadrupling E buys only about 41% more span. Units must be consistent (E psi, OD/ID in, w lb/in, δ in → L in inches).
| I — section moment of inertia | 7.56253 | in⁴ |
| Maximum deflection-limited span | 109.772 | in |
The result values above are locked as fixture support-span.json, case
“FRP 4in, E=1e6 psi, w=2 lb/in, delta=0.5 in, simple span (c=5/384)”, tolerance 0.001, in the calc-core continuous
verification gate (see https://pipingtoolset.com/trust/validation.html). Allowable-stress and factor data are
user-supplied inputs; citations: ASME B31.3, Process Piping — ¶321.1.1, support spacing and design to prevent excessive sag, stress and joint leakage; the Code sets the objective, not a span table. · ASME B31.3, Process Piping — Chapter VII ¶A321, support of nonmetallic piping; spacing follows the manufacturer's published deflection and stress limits. · ASME B31.1, Power Piping — §121 Piping Support, including the suggested support-spacing table for standard-wall steel pipe in water/steam service (values user-supplied, not reproduced here). · MSS SP-58 / SP-69, Pipe Hangers and Supports — Materials, Design and Application / Selection and Application; tabulated maximum spans referenced only, never reproduced. · Elastic beam theory (Roark, Table 8.1, simply supported and continuous uniformly loaded spans) — the source of the end-condition coefficient c.