Question

(a) During the weighment of CO2 bottles required for total flooding of Engine room, it was observed that few bottles are less than the original capacity. State the reasons for the same and checks / tests to be made prior refilling.

(b) With reference to MSCI /Circ. 1318/Rev. 1, high pressure cylinders (CO2 bottles) are subjected to an internal inspection and hydrostatic test. State the stipulated criteria for such hydrostatic test and periodic test interval of high pressure cylinders (CO2 bottles).

Answer 1

Part (a)

CO2 BOTTLES LESS THAN ORIGINAL CAPACITY - REASONS, CHECKS/ TESTS BEFORE REFILLING

Reasons for the bottles being less than the original capacity:

Leakage of CO2 from the bottles (through the valve, seals, or a damaged bottle) over time.
The bottle was not fully charged at the last refill.
A faulty/ leaking valve or a damaged bottle.
The bottle was discharged/ partially discharged (e.g. during a test or a false activation).
Temperature effects (the weight/ pressure varies with temperature, but the charge weight should be constant).

Checks/ tests to be made prior to refilling:

Weigh the bottle and compare with the original/ marked charge weight to confirm the deficiency.
Inspect the bottle and valve for damage, corrosion, leakage and the condition of the seals.
Check the bottle's test/ inspection date (the bottle must be within its test period).
Leak-test the valve/ bottle (e.g. soapy water/ leak detector) to identify any leak.
If the bottle is within its test period and not damaged, it can be refilled to the correct charge weight.
If the bottle is due for test or is damaged, it must be tested/ inspected before refilling (see part b).

Part (b)

HYDROSTATIC TEST AND PERIODIC TEST INTERVAL OF HIGH-PRESSURE CO2 CYLINDERS (MSC.1/Circ.1318/Rev.1)

Per MSC.1/Circ.1318/Rev.1, high-pressure CO2 cylinders are subjected to an internal inspection and a hydrostatic test at periodic intervals.
The stipulated criteria for the hydrostatic test: The cylinder is filled with water and pressurised to the test pressure (typically 1.5 times the working/ charging pressure, or as specified by the standard/ Class). The cylinder must withstand the test pressure without permanent deformation, leakage or failure. The test is carried out by an approved/ competent body.
The periodic test interval: High-pressure CO2 cylinders are subjected to the internal inspection and hydrostatic test at intervals of 10 years (as per the IMO/ MSC circular and the relevant standards). The test interval may be reduced if the cylinder is damaged or if required by the flag/ Class.
The cylinder is also subjected to an internal inspection (visual/ borescope) at the same interval to check for corrosion, damage and the internal condition.

✓ Verified Model Answer (Text Solution)

CO2 BOTTLES LESS THAN ORIGINAL CAPACITY - REASONS, CHECKS/ TESTS BEFORE REFILLING

Reasons for the bottles being less than the original capacity:

Checks/ tests to be made prior to refilling:

HYDROSTATIC TEST AND PERIODIC TEST INTERVAL OF HIGH-PRESSURE CO2 CYLINDERS (MSC.1/Circ.1318/Rev.1)