Section 3 Use of Natural Gas as Fuel

301. General

Boilers, gas turbines and internal combustion engine using produce gas as fuel are to comply with the requirements given in Pt 7, Ch 5, Sec 16 of Rules for the Classification of Steel Ships in addition to requirements given in this Chapter.

302. Ventilation systems

1. The ventilation of boiler and engine rooms is to be carried out at pressures which exceed atmos- pheric pressure. Main ventilation systems are to be independent of all other ventilation systems. The number of pressure fans for boiler and engine rooms are to be such that capacity is not reduced by more than 50%, if one fan is out of operation.

2. Ventilation systems are to ensure good air circulation in all spaces, and in particular, ensure that there is no possibility of the formation of gas pockets in any space.

303. Gas fuel supply systems

Gas processing systems including storage vessels, compressors, separators, filters, pressure control valves, etc., are to be located in hazardous areas and separated from boiler and engine rooms by gas- tight bulkheads.

304.

Enclosed spaces above decks having boilers and engines

1. Enclosed spaces above decks having boilers and engines using produced gas as fuel, are to have ventilation systems providing at least 30 air changes per hour.

2. These spaces are to be fitted with gas detection systems to alarm at 20% L.E.L., and to activate automatic shutdown of the gas supply at 60% L.E.L.

3. The automatic shutdown valve is to be located outside the space. This valve is also to be activated upon loss of the required ventilation in the enclosed space, and upon detection of abnormal pres- sure in the gas supply line.

305. Gas containing hydrogen sulfide(H2S)

1. For produced gas containing hydrogen sulfide(H2S), provisions are to be made for gas sweetening, unless the equipment manufacturer has certified the suitability of the equipment for sour gas appli- cation, and the equipment is located in a freely ventilated open space.

2. To bring fuel gas containing H2S to the equipment located in an enclosed machinery space, the sour gas is to be sweetened. Additionally, the machinery space is to be equipped with H2S gas

detectors. ppm.

The detectors are to be set to alarm at 10 ppm and to activate the shutdown valve at 50