I. PRESSURE
US Hose pressure ratings are in accordance with industry-widegood practice and are consistent with the requirements of the. USA Standard Code for Pressure Piping and the ASME Boiler and
Pressure Vessel Code, Sec. VIII.
Maximum Working Pressure
Maximum operating pressure to which the hose should be subjected.It is established at 25% of the Nominal Design Burst.
Pressure. The hose may be deflected within the specified bend
radius range.
Maximum Proof Pressure
Maximum test pressure to which the hose should be subject. It is established at 150% of the Maximum Working Pressure withthe hose installed straight. No harmful deformation shall occur. Hydrostatic field tests of hose assemblies installed in varying degrees of radial bend or parallel offset should be limited to
120% of the maximum rated working pressure at 70°F, or 150%
of the actual operating pressure, whichever is lower.
Nominal Design Burst Pressure
The pressure at which the hose can be expected to rupture,based on the minimum annealed ultimate tensile strength ofthe braid wire and corrugated hose alloys at 70°F and the hose installed straight.
Pulsating or Shock Pressures
When pulsating, surge or shock pressures exists, such as occurdue to fast closing valves, the peak pressure shall not exceed50% of the Maximum Working Pressure. Installation shall be such that there is no initial slack in the braid when the pressure pulse, surge or shock occurs.
Pressure Relative To Unbraided Hose
At Maximum Working Pressure, 1 to 21/2% elastic elongation will occur in unbraided hose assemblies. To avoid squirm, unbraided hose should be unrestrained at one end, or installed in such a manner as to allow free axial expansion due to pressure, as in a 180° loop.
Pressure Relative To Braided Hose
Whenever appreciable internal pressure is applied to a corrugated metal hose, it will elongate unless restrained. Generally this restraint is provided by a wire braid sheath over the hose. The braid has little effect on bending or flexibility of the hose.
However, in extremely short lengths of braided and pressurized hose, additional bending forces are required because of braid
friction.
Where the strength of the braid sheath is the limiting factor, additional working pressure may be gained by using a heavier than standard single braid, or two or more braids. However, when the hoop rupture strength of the corrugated hose is the limiting factor, no additional pressure resistance is gained with
additional braids. Contact US Hose Engineering Group for braid/hose design assistance to determine maximum pressure ratings at lowest total cost for an application.
Pressure Relative To Temperature
For operating temperatures in excess of 70°F, the tabulated pressures must be decreased in accordance with the
“Conversion Factors” listed in the table below. Since the pressure ratings are based on annealed material properties, no reduction in pressure ratings is necessary for fitting attachment
by TIG welding, brazing, or soft solder.
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