Hold bilge systems

Prior to loading a bulk or general cargo, hold testingand inspections must be carried out to ensure thateverything is in good working order.

Bulk cargoes are required to comply with the BLU Codesection 2.2. Additional guidance can be found in ‘BulkCarrier Practice’ published by the Nautical Institute.

Debris from most bulk and general cargoes willinevitably find its way into the hold bilge areas and hasto be removed manually. After cleaning of the bilge areait is important that the bilge sounding pipes, bilgesuctions and bilge non return valves are tested andverified as working correctly.

Sounding pipesSounding pipes can become blocked and unusable as aresult of cargo residues being left in the bilge well andentering the bottom of the sounding pipe, where over aperiod of time the cargo residue will dry out and solidify.This problem can be prevented if the sounding pipesare hosed out with water from deck level after the holdhas been washed and the bilges have been cleaned.Alternatively an airline can be used to clear out blockedsounding pipes.

Broken sounding rods left in the sounding pipe are alsoa problem and it is essential that these are removed.

Sounding caps left off or not fully secured duringloading or discharging operations increase the risk ofcargo entering the sounding pipe and causing ablockage.

Inspectors have recently noted that the maintenance and testing procedures of hold bilge systemsonboard bulk carriers and general cargo ships are being neglected. These oversights may haveserious consequences, resulting in unnecessary cargo claims.

Striking plates for the sounding pipes are situated in thehold bilge well and should be checked for wastagewhen the bilges have been cleaned.

Bilge suctionsThe bilge suction line in the hold bilge is normally fittedwith a perforated strum box which prevents cargodebris from entering the bilge line. The strum box shouldbe thoroughly cleaned after each cargo discharge andif possible, dismantled and checked for damage orcorrosion. The end of the bilge suction line must beconfirmed as clear, with no debris fouling the end of thesuction pipe.

Hold suction arrangement

Technical BulletinNUMBER 29 OCTOBER 2008

UK P&I CLUB

To check that the bilge suction and bilge suction lineare clear and working correctly, a nominal amount ofclean water should be poured into the bilge well andpumped out.

Non return valvesNon return valves are fitted in the hold bilge pumpingsystems to ensure that water pumped from the holdbilges to the engine room and over-side or into a holdingtank cannot flow back via the bilge line into the holdbilge wells and then into the cargo hold.

Regrettably many ships are neglecting to test and verifythe effectiveness of these non return valves.

If cargo debris is trapped in any of the non return valvesit will reduce the pumping efficiency of all the otherhold bilges.

The easiest way to test the non return valve is to stopthe pump (or eductor) and allow water to flood backinto the bilge line up to the non return valve. If no waterenters the hold bilge then the non return valve isworking correctly. However if water flows into the holdbilge, the non return valve, normally situated in thestool space or duct keel, is not working correctly. Thenon return must then be opened up and cleaned andchecked for wear, deformation, dents or damage to anyof the structure or fittings.

It is prudent seamanship for all non return valves onthe bilge line to be overhauled on a regular basis andthis should be a requirement included in the shipsplanned maintenance system. Following the testing ofbilge non-return valves an entry should be made in thedeck log.

Spectacle flanges and holdblanksBulk carriers often have an eductor or ejector systemto allow the easier cleaning of cargo holds and removalof accumulated cargo debris and (washing) sea water.This arrangement requires an additional eductor bilgewell fitted in the holds, either amidships or to port andstarboard in each hold.

Sea water used to drive the hold cleaning eductor isnormally taken from the deck wash line. At the pointwhere the branch line carrying the drive water for thehold eductor leaves the deck wash line, two valves withspectacle flanges and a spool piece are usually fitted.These spectacle flanges prevent accidental holdflooding when the deck line is pressurised.

Hold suction filters

It is most important that when the hold cleaning eductorsystem is not in use, the spectacle flanges must beturned so that the blank spool piece is in the closedposition to prevent water flooding back into the cargohold cleaning line.

Typical small eductor

Spectacle blank in open position

In addition to the spectacle flanges fitted on deck, thehold cleaning eductor bilge well space in the hold, mustalso be blanked off.

The discharge line from the hold eductor is usuallyfitted with a gate valve and a blank at the open end ofthe discharge line at 900mm above the deck togetherwith a blank flange. When not in use the gate valvemust be closed and the blank flange fitted with a gasketand all of the securing bolts.

Checklist● Sounding pipes clear

● Striking plates in hold bilge wells not wasted

● Bilges clean and dry

● Strum boxes clean

● Test bilge suctions

● Test bilge suction non returns

● Spectacle pieces for hold cleaning eductorsin CLOSED position after hold cleaningcompleted

● Hold cleaning eductor discharge line valveclosed and blank flange fitted after holdcleaning completed

● Hold cleaning eductor bilge space blankedoff.

Spectacle blank in closed position

UK P&I CLUBIS MANAGEDBY THOMASMILLER

For further information please contact:Loss Prevention Department, Thomas Miller P&I LtdTel: +44 20 7204 2307. Fax +44 20 7283 6517Email: lossprevention.ukclub@thomasmiller.com