Three decisions set the part number: how the corrugation is
formed, how tightly it is pitched, and how many braids go over it. Each one trades
pressure against flexibility, and the right answer depends on the duty rather than
on which hose is strongest.
1. Forming method sets the bore
Mechanically formed (MF) covers 6 mm to 50 mm
bore and reaches 190 bar working pressure with a double braid.
It is the small-bore, high-pressure family.
Hydroformed (HF) covers 40 mm to 300 mm
— up to 12 inch — and works to 55 bar. Large bore
means large end loads, so the pressure ceiling comes down as the diameter rises.
Between 40 mm and 50 mm both families are available.
Elastomer formed (EF) uses an elastomer mandrel to form the
convolutions, which gives tighter bend radii and more flexibility than either
mechanical or hydroforming. Specifications are in preparation —
ask us for EF sizes and ratings.
2. Pitch buys flexibility, costs pressure
Pitch is the distance between one convolution and the next. Packing them closer
makes the hose bend tighter, and the same geometry that lets it flex makes it
hold less pressure.
Taking the small-bore mechanically formed range as the comparison:
Standard pitch (11) — 190 bar, static bend radius from
25 mm.
Close pitch (12) — 185 bar, bend radius from
20 mm.
Extra close pitch (13) — 10 bar, bend radius from
11 mm.
Series 13 is the flexible-conduit answer, not a pressure hose: it is supplied
unbraided and belongs where the hose has to turn inside a tight space.
3. Braiding carries the pressure
The corrugated tube seals; the braid restrains it. An unbraided
hose is rated to 12 bar at most and carries no burst figure
— it is for movement, venting and conduit duty, not containment.
A single braid takes the working pressure up sharply; a
double braid takes it to the series maximum. Braid is supplied
in the same grades as the tube.
Across all 130 part numbers, burst pressure is exactly four times the
maximum working pressure — a 4:1 safety factor with no exceptions.
Materials
Tube and braid are both available in SS 304, 316 and 321 and in the
low-carbon 304L, 316L and 321L grades. The L grades restrict carbon
to reduce sensitisation at the weld, which matters where the assembly is welded or
held at temperature. SS 321 is stabilised with titanium and
carries the widest service range, −270 °C to +700 °C.
SS 316 adds molybdenum for chloride resistance.
Pressure ratings are quoted at ambient. Above that they must be derated using the
ISO 10380 factor for the grade — the
temperature correction table gives
the figures, and the
pressure rating tool applies them for you.
