CTR K

Pipe Stress — validation & limitations

What this calculator checks and the method behind each result, the independent reference cases its engine is tested against, and what it does not check. Use it to decide how far you can rely on a result.

Open the Pipe Stress

What it calculates

Standard / method: ASME B31.3

ASME B31.3 Process Piping — §304 wall thickness, §319 thermal expansion, §302.3.5(d) displacement-stress allowable, Appendix D / B31J SIF/flexibility factors

Engineering estimate — this tool uses an accepted simplified model rather than one citable governing standard. Use it for preliminary sizing and verify the final design against manufacturer data or a qualified engineer.

  • ASME B31.3 thermal expansion stress and axial thrust force for fully restrained or free-end pipe runs
  • Minimum wall thickness from B31.3 Eq. (3a) with corrosion allowance, mill tolerance and weld-joint quality factor
  • Expansion loop height and width sizing (Kellogg guided-cantilever method, closed-form, with correct E-dependence)
  • ASME B31.3 §302.3.5(d) displacement-stress-range check S_E ≤ f·[1.25(S_c+S_h) − S_L], and Appendix D SIF/flexibility factors for bends
  • Support span optimisation to the ASME B31.1 §121.5 / MSS SP-69 basis (2.5 mm sag plus a bending-stress limit) for insulated, fluid-filled pipe
  • Pressure-cycling fatigue life estimate for welded pipe (S-N method, flagged as engineering estimate)

Standards this tool applies

  • ASME B31.3 — ASME B31.3 §304 wall thickness (Eq. 3a), restrained thermal stress (direct E·α·ΔT upper bound), Kellogg expansion-loop sizing and the §319.4.4 / §302.3.5(d) displacement-stress-range check. The §319.4.1(c) formal-analysis screen is not evaluated.

Validation evidence — independent reference cases (0)

Each case runs the tool's engine on a worked example whose values come from a published source or a hand derivation from the cited equations, and an automated regression test asserts the engine against those values within the stated tolerance. "Conservative" means the engine is known to sit on the safe side of the reference and the test asserts that side. Sources are cited; their text is not reproduced.

No independent reference case is registered for this tool yet. Its engine is covered by the regression suite, but no published worked example has been reproduced end to end.

Limitations

Not checked by this tool

  • Occasional loads: wind, seismic, water hammer, relief-valve thrust — Not included; evaluate occasional stresses per ASME B31.3 section 302.3.6
  • External pressure / vacuum on the pipe — Internal pressure only; check external pressure per ASME B31.3 section 304.1.3
  • Formal-analysis screen of ASME B31.3 section 319.4.1(c) — Not evaluated; apply D·y/(L-U)^2 <= 208 000 by hand for two-anchor systems
  • Branch-connection reinforcement (ASME B31.3 section 304.3) — Not checked; calculate the reinforcement area per section 304.3.3
  • Flange pressure-temperature rating — Check the flange class against ASME B16.5 for the material group
  • Nozzle loads on connected equipment (pumps, vessels) — Not checked; compare the piping loads with the equipment's allowable nozzle loads

Results are engineering calculations for qualified users — see the disclaimer. Other tools: all validation pages · standards reference · symbols glossary.