Answer MEP Question 60

Q. During the cleaning & inspection of the oily bilge tank onboard your vessel; 

A. As the second engineer, explain the procedure involved in transferring the water, emptying out the tank, without violating MARPOL Regulation. 

B. List the precaution to be taken before entering and while cleaning the progress. 

C. Explain what all checks are to be carried out, before and after cleaning.

A. As the second engineer, explain the procedure involved in transferring the water, emptying out the tank, without violating MARPOL Regulation. 

a. Discharge the oil-water mixture overboard through an approved OWS to bring the level of the tank to the minimum possible, care must be taken for the position of the vessel. Entry of the operation to be made in the ORB-I.

b. At an un-pumpable level stop the OWS, the remaining mixture shall be manually taken out and transferred into drums. Permission from the flag state administration will be required for retaining the oily-water mixture or sludge in the drums. Entry to be made in ORB-I  for the collection of the oily-water mixture into drums. 

c. A weekly entry in ORB-I for the retention of the mixture in the drums is required to be made until it is disposed to shore facility or burnt in the incinerator. An entry for incineration of disposal to shore facility is also be made in ORB-I.

d. Tanks will be inspected before and after the cleaning. The oily garbage generated during the cleaning process is required to be incinerated or disposed to shore facilities, the entry of this operation is required to be made in GRB.

B. List the precaution to be taken before entering and while cleaning the progress.

A bilge tank is an enclosed space, which requires all the precautions for entering an enclosed space viz planning for entering, ventilation of space, permit for entering, testing of the atmosphere, the entry in the space and work in space.

a. Planning and risk assessment for entering: 

• Prior to entering an enclosed space, all personnel who are to be involved in the work should meet to define the purpose of entering the space, identify the steps required to achieve the purpose, identify the risks involved, develop a plan of action; and agree on responsibilities.
• Under the Master's authority, an officer should be designated with responsibility for the work and for compliance with related procedures; Enclosed spaces should not be entered until it is confirmed that the atmosphere is safe and then only for a specifically authorised purpose.
• The tank cleaning plan should not permit personnel to enter a tank unless it is confirmed safe for entry. Atmosphere testing should be done by personnel trained in the use of the equipment used considering the manufacturer's recommendations for calibration. 
• A trained attendant be responsible for initiating emergency procedures in the event of an incident; should be designated who should remain outside the entrance to the enclosed space. Their primary function is to maintain a safety watch over the work and personnel involved and to maintain communications. 
• Identification and mitigation of physical hazards, identification of safety, fire-fighting, communication, escape and rescue and other equipment and tools required;
• Information to personnel entering enclosed spaces on the particular hazards of the operation, how to maintain safe operating conditions in the enclosed space; and a review of emergency procedures, including that:
• The rescue party leader should coordinate operation from close to the enclosed space access but should NOT enter the space;
• Sufficient personnel should be available to recover a casualty from the enclosed space;
• The rescue team should have sufficient personnel, all trained in the use of rescue equipment and first aid; and A decision to recover a casualty from the enclosed space should assess the nature of the injury and the need for immediate first aid against the risk associated with remaining longer in the space.

b. Ventilation of space: 

Allow sufficient time for the ventilation of the space naturally and mechanically. Guard any opening for accidental and unauthorized entry.

c. Permit for entry: 

Prior to allowing personnel to enter an enclosed space, an entry permit should be issued. It is recommended that the permit should be signed by the Master or a designated officer with sufficient knowledge and experience of the procedures requiring compliance. The entry permit should contain a clear indication as to its maximum period of validity, which should not exceed 8 hours. It should also describe the maximum permitted time between testing of the atmosphere and entry of personnel into the space. Except for entering a cargo tank, A separate permit for entry into more than one enclosed space is required to be issued as defined in the company's SMS. 

d. Testing of the atmosphere: 

Atmosphere testing should be done by personnel trained in the use of the equipment used considering the manufacturer's recommendations for calibration. The atmosphere must be tested for oxygen content, flammable gases, toxic vapours.

A safe for entry rest reading is as follow;

Oxygen % vol- (21%)

Hydrocarbon % LFL - less than 1% 

Toxic gases ppm - less than 50% OEL of the specific gas.

e. Entry in space: 

During entry, ensure the space is suitably illuminated, Wear the right PPE, continue to ventilate the space, test the atmosphere at regular intervals, communicate regularly, be alert and leave the space when requested or if you feel ill.

After entry, ensure all equipment and personnel are removed from the space, close the access of the space to prevent unauthorized entry, close the entry permit, reinstate any system as appropriate.

f. Work in space: 

Ventilation should be continuous while personnel are inside the space and the atmosphere should be monitored at appropriate intervals, including by the use of personal multi-gas detectors. If personnel begin to feel dizzy or unwell they should leave the space immediately. In particular, tests should be made before the resumption of work after a break and prior to re-entry.

Hot work in an enclosed space should only be carried out when all applicable regulations and safety requirements have been met and a hot work permit has been issued in addition to the tank entry permit. A full risk assessment should also be carried out and risk mitigation measures implemented before any work commences.

C. Explain what all checks are to be carried out, before and after cleaning.

Tank drawing and inspection records should be consulted for details that may influence the cleaning process eg. potential pockets or drainage systems. A visual external inspection of the tank should complement the review, taking into account proposed drainage routes, recirculation loops and positive isolation positions.

Tank roofs shall be externally inspected only after records have been reviewed for potential corrosion problems and then by a minimum of two persons. The tank surrounds should be inspected to ascertain access possibilities, firefighting resources and potential sources of ignition.

The extent of cleaning is dependent on the reasons why the tank is to be cleaned. A range of possibilities, therefore, exists according to the reasons for the cleaning and the condition experienced upon an inspection at an early stage in the process.

It is recommended that after initial gas-freeing the tank is inspected to ascertain the full extent of the cleaning process.

Hot Work Standard of cleaning

This is the degree of cleaning required to enable hot work to take place in the tank. After removal of all products and sludges, the tank must be tested to demonstrate a gas-free condition. The gas-free condition applies to all void spaces and under the tank bottom plates.

After the tank plates have been cleaned to show a waxy, greasy film they are to be washed to a metal finish. This may be achieved by:

• hot water washing.
• cold water spray or jetting under high pressure.
• diesel washing.
• kerosene washing.
• chemical washing with detergents.
• manual wiping.

The cleaning method selected will depend on the product stored, the degree of cleanliness already achieved and the local means available. If diesel washing is selected then it should be applied at very low pressure, the tank atmosphere continuously monitored and the residue washed off the walls with water.

Washing with hydrocarbons having a higher volatility than kerosene is prohibited. The selection of any detergents should be considered carefully taking into account any toxic vapours that may be released.

Wash water containing chemicals, detergents or oils will be detrimental to the efficiency of the site interceptors and will require additional treatment and disposal.

Inspection Standard of cleaning

This is similar to Hot work standard but requires a higher finish on welded and bolted areas. Any abrasives used should not contain silica.

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