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PART IX
MAINTENANCE AND TESTING

General

55. (1) As the safety arrangements are an integral part of the inert gas system, it is important for ship’s staff to give special attention to them during any inspection.

(2) Inspection routines for some of the main components are dealt with in this section.

Inert Gas Scrubber

56. (1) Inspection may be made through the manholes; checks should be made for corrosion attacks, fouling and damage to:

1. scrubber shell and bottom;
   
2. cooling water pipes and spray nozzles (fouling);
   
3. float switches and temperature sensors;
   
4. other internal components such as trays, plates and demister filters.

(2) Checks should be made for damage to non-metallic parts such as:

1. internal linings;
2. demisters;
3. packed beds.

Inert Gas Blowers

57. (1) To a limited degree, internal visual inspection will reveal damage at an early stage; diagnostic monitoring systems greatly assist in maintaining the effectiveness of the equipment; an acceptable level of availability of blowers is ensured by fitting two equal blowers or, alternatively, supplying and retaining on board a spare impeller with a shaft for each blower; visual inspection through the available openings in the blower casing is adequate for this purpose.

(2) An inspection of inert gas blowers should include:

1. internal inspection of the blower casing for soot deposits or signs of corrosive attack;
   
2. examination of fixed or portable washing system;
   
3. inspection of the functioning of the fresh water flushing arrangements, where fitted;
   
4. inspection of the drain lines from the blower casing to ensure that they are clear and operative;
   
5. observation of the blower under running conditions for signs of excessive vibration, indicating too large an imbalance.

Deck Water Seal

58. (1) This unit must be maintained in good condition as it performs an important function; corroded inlet pipes and damage to float controlled valves are not uncommon; the overboard drain line and connection are also possible sources of trouble.

(2) An inspection of the deck water seal should include:

1. opening for internal inspection to check for:
   1. blockage of the venturi lines in semi-dry type water seals;
   2. corrosion of inlet pipes and housing;
   3. corrosion of heating coils;
   4. corroded or sticking floats for water drain and supply valves and level monitoring.
2. testing for function:
   1. automatic filling and draining (check with a local level gauge if possible);
   2. presence of water carry-over (open drain cocks on inert gas main line) during operation.

Non-return Valve

59. The non-return valve should be opened to check for corrosion and also the condition of the valve seat; the valve should be tested in operation.

Scrubber Effluent Line

60. The scrubber effluent line cannot normally be inspected internally except when the ship is in dry dock; the ship side stub piece, referred to in paragraph 27(3)(b), and the overboard discharge valve should be inspected at each dry-docking period.

Testing of Other Units and Alarms

61. (1) A method should be devised to test the functioning of all units and alarms; it may be necessary to simulate certain conditions to carry out an effective testing programme.

(2) Such a programme should include checking:

1. all alarm and safety functions;
   
2. the functioning of the flue gas isolating valves;
   
3. the operation of all remotely or automatically controlled valves;
   
4. the functioning of the water seal and non-return valve (with a backflow pressure test);
   
5. the vibration level of the inert gas blowers;
   
6. for leakages: deck lines in systems four years old or more should be examined for gas leakage;
   
7. the interlocking of the soot blowers;
   
8. oxygen-measuring equipment, both portable and fixed, for accuracy by means of both air and a suitable calibration gas.

Suggested Maintenance Programme

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