P&I club Gard has warned that a serious source of engine damage can come as a result of automatic backflush filter failure.
Automatic backflush filters are designed to protect engines by keeping fuel and lubricating oil clean. The filters generally consist of one or more chambers with a set of candles of fine wire mesh that the oil flows through. Larger particles get stuck on the surface while smaller particles flow through the filters and back into circulation.
Gard highlighted that several claims have shown this fine filter mesh has disintegrated in use, resulting in pieces of the wire mesh entering the lube oil system and severely damaging engine bearings.
Differential pressure concerns
Pressure-triggered rinsing cycles are an inherent risk. If the filter candle mesh start disintegrating, the mesh becomes riddled with holes. With enough ruptures, the differential pressure drops, as the oil will follow the easiest route through the mesh. This will lead to a free flow through the housing, with oil potentially carrying wire mesh parts directly into the engine. From the cases seen there have been no warning of this prior to engine taking damage.
The damages
The small wires of the mesh break off and can travel through the entire lubrication system, causing severe damage. This damage will be primarily located on bearing surfaces on camshafts and crankshafts. This will in turn create severe surface deterioration and breakdown that can damage the engine even further and lead to dangerous situations. Replacement of main bearings and even the crankshaft itself can be very expensive and time consuming.
In one Gard case, replacement of a crankshaft is expected to cost 2.2 million USD with an 8-12 week period just to source the new equipment.
Where deterioration of the mesh is found, mechanical and chemical cleaning of the entire system affected will be required prior to operation. If the cleaning process is substandard, new damages may arise swiftly after repairs have taken place.
Gard Recommendations:
To maintain backflush filters and prevent damage due to deterioration:
- Ensure the correct manual and procedures for the actual filter system installed are available onboard the vessel and that the crew have been adequately familiarised and trained.
- To ensure safe operation of the backflush filters, procedures on manual handling addeherent to makers reccomendations should be in place, together with clear procedures on when filters are to be taken out of use due to damage and risk of failure.
- The engine crew should be trained to spot even minor damage to the candles. Training on how to handle the filters with care during cleaning is vital. We recommend having cleaning tools onboard like an ultrasonic cleaner unit or cleaning gun which blows horizontally onboard,
- If not already installed, a strainer or in-line filter should be installed after the backflush filter to ensure debris from candle disintegration is captured before it contaminates the oil system.
- Use OEM parts. If in doubt, contact your filter manufacturer for advice.
Read the full advice, including how to avoid serious incidents: Gard – Beware of backflush filter failures