Short answer
In underwater work the breaker itself does not change, its maintenance regime does. Three things come under strain at once: water tries to enter the housing, grease is washed out of position, and when work stops the moisture left inside starts corrosion. None of this shows while the work is going on; all of it appears weeks later as bushing wear, failed seals and pitting on the piston surface. Which is why, in underwater work, the real job is done after the work rather than during it.
Three ways water gets in
The first is the gap between tool and bushing. As the breaker strikes, that gap opens and closes and a little water is drawn in on every cycle. The only thing that prevents it is keeping that gap permanently full of grease.
The second is the housing’s breathing and assembly points. On a breaker taken into water, if internal air pressure cannot balance the water pressure outside, water seeps in at those points. That is why the housing is fed with compressed air for underwater work.
The third is the one most often missed: the housing cooling down after work. As a hot housing comes out of the water and cools, internal pressure falls and it draws in the moisture around it. That is why the after-work procedure matters as much as anything done during the work.
Why grease is managed differently when wet
On land, grease put in once stays where it is put for a while. In water it does not: movement and flow wash it out of the bushing mouth. The result is that a greasing frequency which is adequate on land is not adequate in water.
The second difference is that the grease takes on a second job. On land it lubricates; in water it lubricates and seals. A grease cushion standing permanently at the bushing mouth physically blocks water from being drawn in.
Between them, those two reasons make greasing in underwater work something that cannot be left to the operator’s memory. An arrangement that meters grease continuously makes more difference in the wet than it does on land.
What HKM uses
SolidLube: keeping the grease cushion continuous in water
Used with the automatic station, the high temperature grease cartridges with solid additives meter grease during the blow itself. In wet work, keeping the grease cushion at the bushing mouth continuous is the first barrier against water being drawn in.
Look at the grease cartridges(solid-lube.com)The after-work procedure
- 1
Keep it running as it comes out of the water
Do not stop a breaker the moment it leaves the water; running it briefly in air clears water from between tool and bushing. Keep it short and do not let it turn into blank firing.
- 2
Grease it immediately
The grease cushion washed away by water is renewed. Grease with the tool pressed up until clean grease appears around the bushing. The colour of what comes out also tells you how much water got in.
- 3
Rinse the outside with fresh water
After work in sea water, salt residue is not left on. Once dry, salt starts corrosion under the paint and leaves its mark around the bracket in particular.
- 4
Dry the housing and couplings
Where compressed air is available, dry the coupling mouths and grease points. Water left behind is the source of the moisture that will be drawn in while the machine stands.
- 5
Watch the machine oil and filter
Check the colour of the hydraulic oil after underwater work. A milky cloudiness means water has entered the system, and the contamination chain starts there.
- 6
Take the tool out if it will stand overnight
If a standstill is coming, remove the tool, dry its shank and oil it. A shank left wet inside the bushing leaves corrosion exactly where it sat.
Do and don’t
Do
- Fill the grease cushion completely before going into the water; any gap left will take water on the first cycle.
- Grease as soon as it comes out, and keep going until the grease is renewed.
- Rinse with fresh water after sea water.
- Check the colour of the hydraulic oil regularly; cloudiness is the first warning.
- Plan underwater work inside the limits set in the machine’s and the breaker’s manuals.
Don't
- Do not take a breaker into water without the configuration for it; if the housing breathing gets wet, the damage is internal and found late.
- Do not leave a breaker ungreased after working in water.
- Do not leave salt residue on the strength of "the rain will wash it".
- Do not leave the tool wet inside the housing through a standstill.
- Do not carry on working once you see cloudiness in the oil; water destroys the oil’s ability to lubricate.
Depth and air supply depend on the product
Permitted depth, the air flow required and how it connects all vary by model, and we do not print figures here. Whether your breaker has an underwater configuration, to what depth it works and what air supply it needs: take that from the manual, or write to us with your model code.
Where this actually comes up
Underwater and permanently wet work is not confined to harbours and rivers. In a foundation excavation with a high water table, a breaker can spend most of the day in water; this is common in foundation work.
The same happens in trenching and infrastructure work: water collecting in the bottom of a trench keeps the working area permanently wet. The breaker is not "underwater" here, but as far as maintenance is concerned there is no difference.
The test is simple: if the area between tool and bushing goes into water regularly, this is wet work and the procedure above applies.