3 Outer duct in gas fuel piping systems (paragraphs 5.4.4 and 5.13.2.4)
1 In section 3, add a new paragraph 3.1 as follows:
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"The expression "duct" in 5.4.4 and 5.13.2.4 should mean to include the
equipment enclosure required in 16.4.3.1 and 16.4.3.2 (e.g. GVU enclosure)
as well as the structural pipe duct intended to contain any release of gas
from inner pipe or equipment. The term "structural pipe duct" should mean an
outer duct forming part of a structure such as a hull structure or
superstructure or deck house, where permitted, other than gas valve unit
rooms.
The gas valve unit rooms should be:
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.1 gastight toward other enclosed spaces;
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.2 equipped with mechanical exhaust ventilation having a capacity of at least
30 air changes per hour and arranged to maintain a pressure less than the
atmospheric pressure; and
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.3 able to withstand the maximum built-up pressure arising in the room in
case of a gas pipe rupture, as documented by suitable calculations taking
into account the ventilation arrangements.
2 Renumber the remaining paragraphs as new paragraphs 3.2 and 3.3 accordingly."