Deluge system
A deluge system is normally the main firefighting system on any Offshore installation, used to protect process-areas, drilling-areas and other high-risk areas. A Deluge system is normally an automatic system, which is triggered by a fire detector in the protected area, and which is using water as the extinguishing agent.
A deluge system consists basically of a Deluge Control Valve, and a distribution piping network with open deluge nozzles. The Deluge Valve is normally closed, and the distribution pipework is dry. The deluge valve is activated automatically when a fire is detected. The distribution piping network is then immediately pressurized, and all nozzles in the system starts flooding the protected area with a predetermined application rate of water.
The deluge valve
is usually installed on a skid together with piping, isolation valves, bypass and
test/drain facility.
Application Deluge
system.
A deluge system may be
used to protect almost any area as it provides:
§
Flame
extinguishment
§
Cooling
§ Fire
control
Deluge systems, using
water or water/foam, will extinguish fires in any, or in a combination, of the
following ways:
§
Surface
Cooling
§
Smothering,
by produced steam
§
Emulsification
§
Dilution
§
Other
factors
Except in very rare
cases, where the application of water may cause certain chemicals to burn or
explode, deluge systems will have a beneficial effect on all types of
fires. Even in cases, such as fires in leaking, pressurized Gas equipment,
where flame extinguishment cannot be achieved, the overall cooling effect, with
the resulting protection of adjacent equipment, will prevent the fire from
spreading and will greatly reduce the damage to both equipment and structure.
The extinguishing
effect of water on Hydro-Carbon pool-fires can be greatly increased using
various types of foaming agent, such as AFFF or ATC.
Hazard types where Deluge
Systems are used:
- Hydrocarbon fires
- Wellhead Area
- Drill floor
- Process Areas
- Storage and Piping facilities
- Gas (Jet) fires
- Wellhead Area
- Drill floor
Material used for Deluge system
One of the major
considerations, when specifying a Deluge System, is resistance against corrosion.
A deluge system will be operated, for testing purposes, only a limited number
of times per year, and yet be required to be fully functional 24 hours a day,
365 days per year. Time has proven the Norwegian Offshore environment very
hostile to equipment, especially those in contact with seawater, which is
stale, i.e. which is not being refreshed continuously.
For this reason, the
material requirements are constantly under development, and there has, on the
Norwegian sector, been a progression, from Steel (Galvanized) over Bronzes
(CuNiFer piping, Bronze valves) and High Molybdenum (6Mo) Stainless Steels to,
now, Titanium.
§
Titanium,
all piping and valves
§ Titanium, with Deluge Valve and permanently wetted Isolation valves in Titanium and normally dry downstream valves and accessories in Al. Bronze
§
CuNi 90/10
piping, with Deluge Valve and isolation valves in Al. Bronze
§
Stainless
Steel 316L piping and valves. (Note: normally used with Cathodic protection)
§ Galvanized
piping, with Bronze (Gunmetal) Deluge Valve and Rubber Lined valves.