6.5 Additional purging and gas-freeing
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6.5 Additional purging and gas-freeing

 Gas-freeing is required on non-inerted product carriers more frequently than on crude carriers, both because of the greater need for tank entry and inspection, especially in port, and for venting vapours of previous cargoes. On inerted product carriers any gas-freeing operation has to be preceded by a purging operation (regulation 62.2.4), but gas-freeing for purely quality reasons may be replaced by purging only. In addition purging may be required on the basis outlined in 6.1.3 above.

It should be recognised that:

  • .1 there are increased risks of air leaking into inert tanks and of inert gas leaking into a tank being entered;

  • .2 purging is not a prerequisite of gas-freeing when the hydrocarbon gas content of a tank is below 2% by volume;

  • .3 the operation of gas-freeing for product purity and where tank entry is not contemplated does not require the atmosphere to have an oxygen content of 21% by volume.

Parent topic: 6 Product Carriers
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