Metal Hose Pressure Derating Guide

Pressure derating is the process of reducing allowable working pressure as operating temperature increases. Flexible metal hose assemblies, expansion joints, braid reinforcement, and end fittings must be evaluated together because the assembly rating is governed by the weakest pressure-temperature component.

Required Inputs

  • Nominal hose size
  • Hose alloy
  • Braid count
  • End fitting material
  • Operating pressure
  • Operating temperature
  • Media type
  • Static or dynamic movement condition

Engineering Rule

The maximum allowable working pressure must be validated at actual operating temperature, not only at ambient conditions. Elevated temperature, pressure cycling, vibration, and repeated flexing can reduce expected service life.

System Factors

  • Temperature: higher temperatures reduce material strength.
  • Dynamic movement: cyclic movement increases fatigue demand.
  • Bend radius: tight bends concentrate stress.
  • Braid layer: braid count affects pressure capacity.
  • End fittings: flange class, thread rating, and weld compatibility must match service conditions.

Recommended Workflow

  1. Identify system design pressure and maximum temperature.
  2. Select material and braid configuration.
  3. Apply pressure-temperature derating.
  4. Check fitting limitations.
  5. Review movement and installation geometry.
  6. Request engineering review for critical service.

Pressure-temperature values used for project submittals should come from current controlled product data for the exact hose construction and assembly configuration. Use the Metal Hose Working Pressure & Temperature Selection page for current public pressure references and the Metal Hose Pressure Derating Calculator for preliminary temperature adjustment.

Need pressure-temperature review for a real assembly?

Pressure derating should be reviewed with hose alloy, braid count, end fitting material, operating pressure, operating temperature, and media. For custom or critical applications, submit the assembly requirements before purchase.