2 Causes
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Marine Environment Protection Committee - MEPC.1/Circular.677 – Guide to Diagnosing Contaminants in Oily Bilge Water to Maintain, Operate and Troubleshoot Bilge Water Treatment Systems – (22 July 2009) - Annex – A Guide to Diagnosing Contaminants in Oily Bilge Water to Maintain, Operate and Troubleshoot Bilge Water Treatment Systems - Annex 5 – Post–treatment (OWS) Oil Sheen - 2 Causes

2 Causes

 There is a range of possible causes due to one or more component, maintenance or operational failure(s) that can in turn lead to multiple system failure(s). These possible causes may not apply to all separator designs and review of the manufacturer’s manual is recommended.

  • ▸ Oil has unusually high specific gravity and/or viscosity, and/or the purge cycle of OWS is inoperable:

    • • Faulty/disabled capacitance probes.

      • Inoperable solenoid valves (purge).

      • Inoperable solenoid valves (pressurize for purge cycle).

      • Leaking isolation valves to allow pressurization.

      • Clogged purge piping – viscous oil.

      • Ineffective heating of upper chamber.

      • Disabled circuitry or probes.

  • ▸ Too much air in system.

    • • Leaking or holed piping on vacuum systems.

      • Inadequate air purging from the system.

      • Inadequate check valves in suction piping.

      • Air may be from the OWS unit itself due to agitation of the effluent in conjunction with a loss of suction (i.e. pressure drop).

  • ▸ Sludge build-up in OWS.

    • • Inadequate maintenance of unit.

      • System overwhelmed with too much bilge water.

      • Too much oil admitted to machine.

      • System operated beyond design capacity.

      • Failure to remove adequately surface oil prior to entering machine.

      • Ingress of high specific gravity oil into the bilge.

      • Excess sludge in bilge holding tanks.

  • ▸ Corrosion or clogging of separator plates.

    • • Too much sludge accumulation (non-buoyant material).

      • Clogged sludge drain valves.

      • Too much solid debris in bilge.

      • Too much solid debris in rose boxes.

      • Internal corrosion of piping.

      • Failed strainers (excessive porosity) in bilge well and inlet piping strainers.

  • ▸ Bypass of OWS.

    • • Internal bypassing of unit.

      • Corroded components.

      • Failed internal gasket(s).

      • Improper reassembly of unit.

      • Short circuiting of fluid flow.

  • ▸ Flow rate too high.

    • • Wrong supply pump configuration.

      • Wrong piping sizes on inlet or outlet.

  • ▸ Pseudo-stable emulsion formed by shearing of pump and transfer operations. See annex 3.

    • • Use of centrifugal pumps on inlet of machine.

      • Low concentrations of soaps and solvents causing pseudo-stable emulsions.


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