 METAL HOSE
Corrugated metal hose allows for the transfer of liquids or gases, usually
at high pressure and high or cryogenic temperature, while remaining flexible.
Corrugation Design
Annular hose is formed from tubing into individual
parallel corrugations. Helical hose is also formed from
tubing but into a continuous spiral corrugation. Both designs allow for
flexibility of the hose assembly under pressure. In addition, helical
hose has unique self-draining properties.
Pitch
Corrugated metal hose is normally manufactured in Standard Pitch (Close
Pitch). Each manufacturer speci fies a standard number of corrugations
per foot based on their desire to provide for acceptable flexibility
while considering economic requirements.
Open Pitch hose is also available and has fewer corru gations
per foot.This hose will not be as flexible as a Standard Pitch hose and
will have a much lower flexing cycle life. Open Pitch hose is intended
to be used in less severe applications where flexibility and cycle life
are not an important requirement or as an effective method for dampening
vibration.
Superflex allows OmegaFlex to achieve greater flexibility
without thinning the wall of the hose by increasing the number of corrugations
per foot. Superflex will normally have a higher flexing cycle life and
can be used in more severe applications where ease of flexi bility
is important.
Wall Thickness
Each manufacturer designs a hose with criteria for the wall thickness
that considers flexibility, cycle life and corrosion resistance. Increasing
or decreasing the wall thickness has both advantages and disadvantages
to the user.
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| Annular |
Helical |
Close Pitch |
Open Pitch |
BRAID
Metal wire braid on a hose assembly provides the hose assembly a higher
pressure capability by acting as a restraint against hose elongation
and acts to dampen vibration. A second layer of braid may be used to
increase pressure ratings provided the test pressure is not exceeded.
Other design considerations may result in the use of a heavy braid to
increase abrasion resistance characteristics.
Braid Coverage
Optimal braid coverage is engineered to contain the core under pressure
and reduce the possibility of squirm. Properly designed braid coverage
will balance pressure capability with flexing requirements. Minimization
of braid wear on the crown of the corrugation is also provided by optimal
braid coverage.
Tubular Braid
Tubular Braid is manufactured by grouping single wires and then braiding
them into an intricate pattern that tightens when the braid is stretched.
Such a group of wires is also known as a strand.
Construction of the braid is expressed as (number of carriers) x (number
of wires in each group) x (wire diameter). An example would be 24 x 8
x .012 where 24 is the number of carriers on the braiding equipment,
there are 8 wires in each strand of wires and the diam eter of each
wire is .012".
Braided Braid
Larger diameter hose assemblies require the strength of Braided Braid.
Braided braid is manufactured the same as tubular braid except that wires
in the strand are braided together prior to the manufacture of the braid.
Construction is expressed the same as tubular braid except the use of
parentheses around the groups of wire and the wire diameter. An example
would be 128 x (21 x .016) where 1 28 is the number of carriers, 21 is
the number of wires in each group and .016" is the diameter of each
wire in the braid. |
