SAMPLE — Variable Spring Hanger Load Variability Calculator

Piping Toolset — Calculation Report

generated by calc-core · 2026-07-21

ProjectSample Project — Demonstration Only	Job No.SAMPLE-001	Client—
CalculationVariable Spring Hanger Load Variability Calculator	Calc byPiping Toolset (calc-core)	Checked byUNCHECKED — sample
Date2026-07-21	Rev0	BasisMSS SP-58 variable-spring variability (25% rule)

1 · Design inputs

General-service line on a variable spring hanger. The stress model reports a 1,000 lb operating load at the support node and 2 in of upward vertical thermal travel. The selected spring has a rate of 50 lb/in, and the project spec allows 25% variability on non-critical lines.

Hot load P_h	1,000	lb
Spring rate k	50	lb/in
Travel Δ (positive up)	2	in
Variability limit	25	%

2 · Method

The spring is treated as a linear element of rate k deflecting through the pipe’s vertical thermal travel Δ:

ΔP = k · Δ

P_c = P_h + k · Δ

V = | k · Δ | / P_h × 100 [%]

pass when V ≤ V_limit

where P_h is the hot (operating) load the support carries, k the spring rate, Δ the signed vertical thermal travel at the support (positive up), P_c the cold or installed load, ΔP the load change, V the variability and V_limit the acceptance limit you enter. Variability takes the absolute value, so it is independent of travel direction; the cold load is not — a positive travel returns a cold load above the hot load. The arithmetic is unit-agnostic: any consistent set works (lb with lb/in and in, or N with N/mm and mm). Outputs are rounded half-up to two decimals.

3 · Calculation

Load change across travel: ΔP = k·Δ = 50 × 2 = 100 lb.
Cold (installed) load: P_c = P_h + ΔP = 1,000 + 100 = 1,100 lb. This is the load the hanger is set and pinned at before the system heats up.
Variability: V = |ΔP| / P_h × 100 = 100 / 1,000 × 100 = 10%.
Verdict: 10% ≤ 25%, so the support passes the supplied limit.

4 · Results PASS

Cold load P_c	1,100	lb
Load change ΔP	100	lb
Variability V	10	%
Limit applied	25	%

5 · Verification statement

The result values above are locked as fixture spring-variability.json, case “general line 10% -> pass”, tolerance 0.000001, 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 — ¶321.2.3, resilient supports. · ASME B31.3, Process Piping — ¶321.1.1, objectives of piping support layout and design. · ASME B31.1, Power Piping — ¶121.7, spring supports (variable and constant-effort hangers). · MSS SP-58, Pipe Hangers and Supports — Materials, Design, Manufacture, Selection, Application, and Installation. The variability limit is a user input; no MSS table values are embedded.

SAMPLE REPORT — auto-generated from a verification fixture to show the report format. Not a project calculation. ⚠ Engineering-aid tool. Public code equations; allowable-stress and factor data are user-supplied. Results MUST be independently verified and reviewed by a qualified/licensed engineer before any design, fabrication, or operation decision.