9 - Pipes & Hoses Flashcards
When carrying out a pressure test on a pipe, to what pressure should it be tested?
1.5 times the working pressure.
When checking a hose after installation for freedom of movement, how should it be flexed?
By flexing through the normal operating range plus 15°.
If the outer cover of a flexible hose is found to be cracked, is the hose serviceable?
It may still be serviceable.
How should shaping be carried out on a rigid hydraulic pipe?
As supplied.
What does fretting corrosion on a braided pipe indicate?
It is unserviceable and should be replaced.
When performing pipe flaring, at what condition is it done?
As supplied.
To allow for shrinkage, vibration, and whip, by how much must all straight hoses be longer than the distance between fittings?
3% longer than the distance between the fittings.
For a flexible hose that cannot be internally inspected, what is the ball test requirement?
A ball of 90% of the bore of the end fittings must pass freely under its own weight.
To what pressure are hoses normally pressure tested?
1½ times maximum working pressure.
What does a fluid line marker with a skull and crossbones represent?
A warning symbol.
What is the international marking for a water injection pipeline?
Chevrons.
What is the international marking for a fire protection pipeline?
Diamonds.
How should aluminium alloy pipelines supported by rubber cleats be treated to prevent corrosion?
They should be treated with varnish over the area of contact.
What is the international marking for an instrument air pipeline?
A zig zag line.
If the maximum distance between end fittings for a straight hose assembly is 50 inches, what is the minimum hose length?
51½ inches.
From where is the length of a hose assembly with elbowed end fittings measured?
From the centre of the bore at the nipple extremity.
What is the international marking for a breathing oxygen pipeline?
Rectangles.
What is the maximum allowable resistance between a flexible hose and a component?
0.05 ohm.
In bore tests of flexible hoses, what size ball should be used relative to the end fittings?
A ball of 90% of the diameter of the end fittings.
What is the ‘Lay Line’ on a flexible hose?
A white line painted the full length of the hose to indicate any twist in the hose.
How is aluminium alloy pipe used for hydraulic systems flared?
As supplied.
What parts are required to make up a flared‑tube fitting?
A sleeve and a nut.
What is the flare angle on an AGS pipe?
32 degrees.
When repairing aluminium pipe using burnishing, what is the maximum allowable damage percentage?
No more than 10%.
Why are rigid pipes designed with bends?
To allow for expansion and contraction due to heat and to absorb vibration.
If a pipe has a flare end fitting of 74°, to which specification has it been manufactured?
A.N.
How are bonding connections between flexible and rigid pipes achieved?
By using a corrugated strip.
