NFPA 302-2020 Fire Protection Standard for Pleasure and Commercial Motor Craft.
NFPA 302-20206.1 General Requirements. 6.1.1 Exhaust systems shall comply with the following: (1) They shall be gastight to hull interiors. (2) All connections shall be accessible. (3) They shall be supported to minimize failure from vibra‐ tion, shock, expansion, and contraction. (4) They shall have no threaded fttings into nonmetallic exhaust system components. (5) They shall have no discharge from other devices into the exhaust other than from engine-cooling water. 6.1.1.1 In addition to the requirements of 6.1.1, exhaust systems on gasoline engines shall be designed and installed to reduce the production of carbon monoxide by providing the minimum restrictions to exhaust gas fow practicable. 6.1.2 Wherever personnel or combustibles can come in contact with hot surfaces, effective protection shall be provided by water-jacketing, lagging, or shielding, or by guards or engine enclosures. 6.1.3 Exhaust Supports. 6.1.3.1 For wet exhaust systems, hangers, brackets, or other means used to support metallic exhaust systems shall be noncombustible within 6 ft (1.8 m) of the engine connec‐ tion(s). 6.1.3.2 For dry exhaust systems, hangers, brackets, or other means used to support metallic exhaust systems shall be noncombustible. 6.1.4 Except for outboard engines, a means to indicate loss of exhaust-cooling water shall be provided so that it is effective at all helm positions. 6.1.5 Non-propulsion engines shall be permitted to use an automatic shutdown device to meet the requirements of 6.1.4. 6.1.6 A separate exhaust system shall be provided for each engine.
6.2.3 The requirements of 6.2.1 and 6.2.2 shall not apply to components furnished as part of an original equipment manu‐ factured (OEM) engine assembly. 6.2.4 The requirements of 6.2.1 and 6.2.2 shall not apply to components of stern-drive and jet-drive installations where exhaust is discharged through the drive system. 6.2.5 Copper shall not be used in contact with dry diesel exhaust gases or within six pipe diameters downstream from the point of water entry in water-cooled exhaust systems. 6.2.6 As installed, nonmetallic exhaust system components shall retain watertight integrity for 2 minutes after a total loss of cooling water, with the engine operating at full power. 6.3 Hose Connections. Except for single-clamped hose furnished for specifc use as part of an OEM engine assembly, hose connections shall be double clamped. 6.4 Temperature Protection. The exhaust turbine side of non- water-jacketed turbochargers and unjacketed, single-wall, dry exhaust components shall be installed so that the temperature of adjacent combustible surfaces shall not exceed 200°F (94°C).NFPA 302 pdf download.