UK P&I Club looks at power loss causesWritten by Nick Blenkey
OCTOBER 1, 2012 — With more ships experiencing sudden losses of power, particularly during and after switching to lower sulfur fuel, the UK P&I Club’s latest Risk Focus bulletin examines the causes of such power losses and suggests mitigating procedures that ships’ crew should adopt.
The club says that, in dollar terms, main engine failures or electrical blackouts now amount to 7 percent of its third party claims for property damage. It says many of these claims have been enormously expensive and in some cases amounted to millions of dollars. Ships effectively out of control as a result of these problems have caused extensive damage to berths, locks, bridges, navigational marks, loading arms, cranes and gantries as well as moored ships. Costly collision and grounding claims can similarly be caused by these failures.
Concern about these rising claims prompted the club to initiate a data collection exercise by its risk assessors and to make a detailed analysis of more than 700 claims.
The club says that it is no exaggeration to suggest that main engine failures and blackouts tend to occur most regularly at the point in a voyage where the ship is at its most vulnerable. In confined waters or entering and leaving port, the stable loads, which will generally prevail with the ship on passage, are disturbed.
There is additionally some evidence that compliance with low sulfur fuel regulations and changing from one grade of fuel to another may have exacerbated these problems.
Reports from pilots, operating in emission control areas where fuel grade changes have been implemented, indicate that these problems have become quite widespread, noting that ships regularly seem to be experiencing power losses, invariably at critical times in their maneuvers and which are attributed to “fuel problems.”
The club’s recent Loss Prevention Bulletin 785-09/11(fuel switching) alerted members to warnings from the U.S. Coast Guard, which had just enforced its own Emission Control Area (ECA) sulfur limits, noting a marked increase in loss of propulsion incidents . Many of these incidents were linked to vessels operating on marine distillate fuels.
The vulnerability of ships to third party property claims has also tended to increase as a result of the “self-sufficiency” of modern vessels. The provision of lateral thrusters has tended to persuade operators to minimize their dependence upon tug assistance in port waters. Previously a vessel experiencing mechanical difficulties would be merely held safely in position by assisting tugs, now, though, a single tug in attendance may not be able to intervene sufficiently when a large ship suffers a blackout or main engine failure at a critical point in maneuvers.
In the club’s investigation, 249 ships’ crews were questioned about their experience with blackouts, main engine failures and fuel switching problems.
As a result of its analysis, the club urges better communication between deck officers and engineers.
Since sudden loss of power is essentially a matter for the engineers to deal with, many of the UK Club’s recommendations are directed towards the engine room team.
Around three quarters of all chief engineers questioned reported blackouts caused by starting bow thrusters and deck machinery such as mooring winches or cranes with insufficient electrical power being available. It is clearly not always realized that the starting current of electrical motors can be several times the full “on load” current and starting large motors can sometimes cause circuit breakers to trip and lead to blackouts. While many modern ships have in-built safety features to prevent this happening, it is still a sensible precaution to have routines in place to ensure that adequate generating power is available before starting large electrical motors.
Engineers also need to warn the bridge of depleted air bottles. Excessive numbers of engine starts/stops during maneuvering will deplete pressure in the main engine start tanks which can result in loss of control of the vessel at critical times, such as when docking, due to the engine failing to start.
A shortage of fuel supply to the generating engines accounted for 64 (16 percent) of reported blackouts, with a high proportion of these attributed to blocked fuel filters. Engineers need to be more thorough when cleaning filters and be aware that if a vessel changes over from higher sulfur fuel (HFO), when marine gas oil is introduced into the system it may act like a solvent, releasing any asphaltenes which then collect in the fuel filters/strainers and clog them.
Recommendations to reduce the risk of power losses and blackouts listed in the bulletin include:
- Engine and boiler manufacturers should be consulted for advice on operation with low sulphur fuel and the need for any equipment/system modifications
- Ensure correct maintenance of all equipment; engines, purifiers, filters, fuel systems and sealing arrangements
- Ensure fuel oil viscosity and temperature control equipment is accurate and fully operational ● Ensure that system temperature and pressure alarms, fuel filter differential pressure transmitters etc are accurate and operational
- Ensure fuel changeover procedures are clearly defined and understood
- Ensure that engineers are fully familiar with fuel systems and main engine starting systems and establish “failure to start” procedures. These should include familiarization with operation locally and from the engine control room
- Ensure that the starting air pressure is monitored during maneuvering operations and that the deck department appreciates the limitations of starting air availability
- Test the astern operation of the main engine prior to arriving at the pilot station and , if practical, before approaching the berth
- Establish procedures to ensure that there is adequate electrical capacity available before starting up lateral thrusters, mooring equipment or other heavy equipment, bearing in mind that simultaneous starting of large electric motors will lead to a large power surge and possible overload.
Download the bulletin HERE
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