(IV-7-3) General Safety

More documents

Recommendations

Info

Rules IV Industrial Services Part 7 Offshore Technology Chapter 3 General Safety Section 8 Active Fire Protection G.2.2 Calculation of the supply of extinguishing gas G.2.2.1 The supply of extinguishing gas shall be calculated based on the net volume of the protected space, at the minimum expected ambient temperature using the design concentration specified in the system's type approval Certificate. G.2.2.2 The net volume is that part of the gross volume of the space which is accessible to the free extinguishing gas including the volumes of the bilge and of the casing. Objects that occupy volume in the protected space shall be subtracted from the gross volume. G.2.2.3 The volume of free air contained in air receivers located in a protected space shall be added to the net volume unless the discharge from the safety valves is led to the open air. G.2.2.4 For systems with centralized gas storage for the protection of more than one space the quantity of extinguishing gas available need not be more than the largest quantity required for any one space so protected. G.2.3 Gas containers G.2.3.1 Containers for the extinguishing gas or a propellant needed for the discharge shall comply in respect of their material, construction, manufacture and testing with the relevant Rules on pressure vessels. G.2.3.2 The filling ratio shall not exceed that specified in the system's type approval documentation. G.2.3.3 Means are to be provided for the installation’s/ unit's personnel to safely check the quantity of medium in the containers. G.2.4 Storage G.2.4.1 Centralized systems Gas containers in centralized systems are to be stored in a storage space complying with the requirements for CO 2 storage spaces, see G.1.7, with the exception that storage temperatures up to 55 °C are permitted, unless otherwise specified in the type approval Certificate. G.2.4.2 Modular systems G.2.4.2.1 All systems covered by these requirements may be executed as modular systems (with the gas containers, and containers with the propellant if any, permitted to be stored within the protected space) provided the conditions of G.2.4.2.2 through G.2.4.2.9 are complied with. G.2.4.2.2 Inside a protected space, the gas containers shall be distributed throughout the space with bottles or groups of bottles located in at least six separate containers. Duplicate power release lines have to be arranged to release all bottles simultaneously. The release lines shall be so arranged that in the event of damage to any power release line, five sixth of the fire extinguishing gas can still be discharged. The bottle valves are considered to be part of the release lines and a single failure shall include also failure of the bottle valve. For systems that need less than six containers (using the smallest bottles available), the total amount of extinguishing gas in the bottles shall be such that in the event of a single failure to one of the release lines (including bottle valve), five sixth of the fire extinguishing gas can still be discharged. This may be achieved by for instance using more extinguishing gas than required so that if one bottle is not discharging due to a single fault, the remaining bottles will discharge the minimum five sixth of the required amount of extinguishing gas. This can be achieved with minimum two bottles. However, the NOAEL value calculated at the highest expected engine room temperature may not be exceeded when discharging the total amount of extinguishing gas simultaneously. Systems that cannot comply with the above (for instance where it is intended to locate only one bottle inside the protected space) are not permitted. Such systems shall be designed with bottle(s) located outside the protected space, in a dedicated room complying with the requirements for CO 2 storage spaces (see G.1.7). Edition 2013 Germanischer Lloyd Page 8–10
Rules IV Industrial Services Part 7 Offshore Technology Chapter 3 General Safety Section 8 Active Fire Protection G.2.4.2.3 Duplicate sources of power located outside the protected space shall be provided for the release of the system and be immediately available, except that for machinery spaces, one of the sources of power may be located inside the protected space. G.2.4.2.4 Electric power circuits connecting the containers shall be monitored for fault conditions and loss of power. Visual and audible alarms shall be provided to indicate this. G.2.4.2.5 Pneumatic or hydraulic power circuits connecting the containers shall be duplicated. The sources of pneumatic or hydraulic pressure shall be monitored for loss of pressure. Visual and audible alarms shall be provided to indicate this. G.2.4.2.6 Within the protected space, electrical circuits essential for the release of the system shall be heat resistant, e.g. mineral-insulated cable or equivalent. Piping systems essential for the release of systems designed to be operated hydraulically or pneumatically shall be of steel. G.2.4.2.7 Not more than two discharge valves shall be fitted to any container. G.2.4.2.8 The containers shall be monitored for decrease in pressure due to leakage or discharge. Visual and audible alarms in the protected space and in the control station stand shall be provided to indicate this. G.2.4.2.9 Each container is to be fitted with an overpressure release device which under the action of fire causes the contents of the container to be automatically discharged into the protected space. G.2.5 Piping and nozzles G.2.5.1 Wherever possible, pipe connections are to be welded. For detachable pipe joints, flange connections are to be used. For pipes with a nominal internal diameter of less than 50 mm threaded welding sockets may be employed. Threaded joints may be used only inside protected spaces. G.2.5.2 Flexible hoses may be used for the connection of containers to a manifold in centralised systems or to a rigid discharge pipe in modular systems. Hoses shall not be longer than necessary for this purpose and be type approved for the use in the intended installation. Hoses for modular systems are to be flame resistant. G.2.5.3 Only nozzles approved for use with the system shall be installed. The arrangement of nozzles shall comply with the parameters specified in the system's type approval Certificate, giving due consideration to obstructions. In the vicinity of passages and stairways nozzles shall be arranged such as to avoid personnel being endangered by the discharging gas. G.2.5.4 The piping system shall be designed to meet the requirements stipulated in G.2.1.4. G.2.5.5 In piping sections where valve arrangements introduce sections of closed piping (manifolds with distribution valves), such sections shall be fitted with a pressure relief valve and the outlet of the valve shall be led to the open deck. G.2.6 Release arrangements and alarms G.2.6.1 The system is to be designed for manual release only. If, in addition to manual release option also an automatic release is provided, suitable measures have to be implemented and approved by GL to ensure that no personal is present in the protected space when the gas is released. The controls for the manual release are to be arranged in lockable cabinets (release stations), the key being kept conspicuously next to the release station in a locked case with a glass panel. Separate release stations are to be provided for each space which can be flooded separately. The release stations shall be arranged near to the entrance of the protected space and shall be readily accessible also in case of a fire in the related space. Release stations shall be marked with the name of the space they are serving. G.2.6.2 Centralized systems shall be provided with additional means of releasing the system from the storage space. Edition 2013 Germanischer Lloyd Page 8–11
Page 1 and 2: IV Rules for the Certification and
Page 3 and 4: Rules IV Industrial Services Part 7
Page 13: Rules IV Industrial Services Part 7
Page 29: Rules IV Industrial Services Part 7

(IV-7-3) General Safety

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?