Short answer
An attachment hose rarely bursts because of pressure. Far more often it is fatigued over months by chafing, stretching or twisting, and it lets go at the worst moment. All three share one thing: a single check at the time of fitting will reveal them, by working the boom end to end and watching the hose. Skip that check and the damage appears not on the first day but months later, when the cause gets recorded as "poor quality hose". Below are the three habits and the mark each one leaves on site.
First: chafing
Chafing is the most common cause and the easiest to see. The hose touches a corner of the boom, a weld bead or a plate on the machine, and wears a little at that point with every boom movement. The outer cover polishes first, then dulls, then the braid shows.
The moment the braid shows the hose has spent its life; its pressure rating at that point is now unknown. Working on from there in the hope of "a bit longer" is not choosing whether it bursts, only when.
The way to stop chafing is not to shorten the hose but to change its route. Where the contact point cannot be removed, spiral guard or a sleeve is used; a guard does not save the hose, it takes the wear onto itself and makes the replacement cheaper.
Second: stretching
Stretching is more insidious than chafing because it leaves no mark. At a particular boom angle the hose reaches its full length and pulls at the fitting. From outside everything looks normal; the hose is only stretched at that angle, perhaps a few hundred times a day.
The result usually appears not in the hose body but at the base of the fitting: first damp, then dripping. On site this is often read as "the fitting has loosened" and tightened; tightening postpones the problem and leaves the cause where it was.
The only way to see stretching is to work the boom through its full movement. Keeping the boom short after fitting and assuming it will be fine simply defers that check by months.
Third: twisting
When a hose is twisted about its axis, the braid layers slide against one another and the rating falls. Twisting usually happens during fitting: the hose turns with the fitting as it is tightened, and that tension stays locked inside.
A twisted hose can be spotted from outside; if the maker’s lettering or the colour stripe along it does not run straight, the hose has been twisted. That stripe is not decoration, it is an assembly check.
Preventing it is simple: hold the hose still while tightening the fitting and put the spanner on the fitting. When tightening is done, confirm by eye that the stripe runs straight.
Shaking is a separate matter with a separate cause
A hose moving about and a hose wearing out are not the same thing. If hoses shake and jump noticeably while the breaker works, the problem may be hydraulic rather than in the routing. We covered that separately: hoses shaking and jumping.
Do and don’t
Do
- Work the boom end to end after fitting and watch the hose; that one check catches all three causes.
- Fit spiral guard or a sleeve at contact points.
- Hold the hose still while tightening the fitting; confirm the stripe still runs straight.
- Route with respect for the bend radius; a sharp turn crushes the inner layer.
- Replace a hose showing wear at a planned standstill; do not wait for it to burst.
Don't
- Do not work with a hose whose braid is showing.
- Do not try to cure a stretched hose by tightening the fitting; the cause is length and route.
- Do not strap or wire a hose tightly to a fixed point on the boom; it needs room to move.
- Do not pair two hoses of different lengths as supply and return; the shorter one stretches first on every movement.
- Do not match only the length when replacing a hose; pressure rating and fitting type have to match too.
When replacement cannot wait
None of those five needs a measurement; all of them are visible. That is the advantage of an attachment hose: reading its early warning takes no tools, only a look.
- Braid showing through the cover: do not wait, replace it.
- Damp recurring at the base of a fitting: do not settle for tightening; find the cause and replace if needed.
- A bulge in the hose body: the inner layer has separated and bursting is a matter of time.
- The stripe not running straight on a newly fitted hose: take it off and refit it correctly.
- A hose that has hardened and lost its flexibility: heat and age have done their work, and it has spent its life even with no visible damage.