A shipyard is a heavy industrial facility with a high fire risk during the construction, repair and dismantling of vessels. The same picture appears on every project: welding, grinding, painting and fuel transfer all run in the same shift. NFPA 312 (Fire Protection of Vessels During Construction, Conversion, Repair, and Lay-Up) defines the rules for dry dock fire systems, hot work permits and gas-free certificates in this chaotic environment. On site, not even a welding machine should be switched on until these three items are in place.
Dry Dock Fire System
- Seawater main: a hydrant every 60 m, supplied at 4,000 L/min
- Foam monitor: AFFF or F3 fixed monitor, 10,000 L/min
- Mobile pump: diesel-driven for access under the hull, usually trailer-mounted
- Dock-side water curtain: a water curtain line above the timber staging
Hot Work Permit
- NFPA 51B: the hot work standard; not a single arc is struck without a permit
- Fire watch: a second person separate from the worker, continuing the watch for at least 30 minutes after the work ends
- Spark blanket: stops sparks falling below or onto the side deck
- Portable extinguisher: 2A:40B:C within 1.5 m of the work point
- Flammable liquids: at least 10.7 m separation, or a physical barrier in between
Gas-Free Certificate
Before any tanker repair begins, a marine chemist steps in:
- An AIHA-certified marine chemist tests the tank in person; there is no remote approval
- Oxygen: 19.5-23.5%
- Lower explosive limit (LEL): below 10%
- H₂S: below 10 ppm
- CO: below 50 ppm
- Benzene (crude oil tankers): below 0.5 ppm
The certificate is valid for 24 hours and is re-verified at the start of every shift. "It was clean yesterday" is not accepted on site.
Onboard Fixed CO₂
- Engine room: CO₂ total flooding under the SOLAS FSS Code
- Design concentration: 40% (diesel), 50% (gas-fuelled machinery)
- Manual release: release from two separate controls is required, with an interlock against discharge on a false alarm
- Special case: LNG carriers favour IG-541 or water mist instead of CO₂
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Download SprinkCalc on the App StoreNFPA 312, NFPA 51B, SOLAS FSS Code, OSHA 29 CFR 1915, AIHA Marine Chemist. NFPA 312 Vessels Construction standard.