(IV-7-3) General Safety

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Rules IV Industrial Services Part 7 Offshore Technology Chapter 3 General Safety Section 8 Active Fire Protection G Fixed Gas Fire Extinguishing Systems G.1 CO 2 fire extinguishing systems G.1.1 Initiation The system is to be arranged for manual initiation of 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 personnel is present in the protected space when the gas is released. G.1.2 Design CO 2 cylinders, associated pressure components and piping shall be approved in respect of materials, design and manufacture. Special attention is to be paid to the risk of icing of quick-flooding lines. G.1.3 Pipes G.1.3.1 The pipes for conveying the gas shall be provided with control valves so marked, as to indicate clearly the compartments to which the pipes are led. G.1.3.2 Wherever possible, welded pipe connections are to be used for CO 2 systems. For detachable connections which cannot be avoided and for valves and fittings, flanged joints are to be used. For pipes with a nominal bore of less than 50 mm, welded compression type couplings may be used. Threaded joints may be used only inside protected spaces. G.1.3.3 All pipes are to be suitably protected against corrosion. G.1.3.4 In piping sections where valve arrangements introduce sections of closed piping (e.g. 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.1.4 Valves and fittings Valves and fittings in the lines from the cylinders to the control valves have to be designed for a nominal pressure of 100 bar, the lines from the control valves to the nozzles for a nominal pressure of 40 bar. G.1.5 Nozzles Discharge nozzles and piping shall be arranged so as to provide effective distribution of gas. G.1.6 Quantity of gas G.1.6.1 The quantity of gas carried shall be sufficient to give a minimum quantity of free gas equal to 35 % of the entire volume of the largest space to be protected. If two or more adjacent spaces protected by CO 2 are not entirely separate, they shall be considered as forming one space. G.1.6.2 The calculation is to be based upon a gas volume of 0.56 m 3 per kg of CO 2 . G.1.6.3 The system is to be so designed that 85 % of the required gas can be discharged into the space within 2 minutes. G.1.7 Gas storage G.1.7.1 Gas cylinder storage rooms or areas shall be situated at a safe and readily accessible position and be effectively ventilated in acc. to an applicable standard used for the design of the system. Any entrance to storage rooms should preferably be from the open deck and in any case shall be independent of the protected space. Access doors shall be gastight and open outward. Bulkheads and decks, which form the boundaries of such rooms, shall be gastight and adequately insulated to prevent a temperature exceeding 45 °C inside the CO 2 room. Any of the boundaries which are contiguous with the protected space are to be A-60 Class divisions. Edition 2013 Germanischer Lloyd Page 8–8
Rules IV Industrial Services Part 7 Offshore Technology Chapter 3 General Safety Section 8 Active Fire Protection G.1.7.2 Pressure relief devices associated with CO 2 cylinders, tanks or manifolds are to be so arranged, that when operated there will be no danger to personnel from the resultant discharge of CO 2 . G.1.7.3 Provision is to be made for changing the cylinders and checking the contents by weighing or by other approved means. G.1.8 Warning Means shall be provided for the automatic giving off audible and visual warning of the release of CO 2 gas into any space to which personnel normally has access. The alarm shall operate before the gas is released for a period of time suitable to evacuate the space to be flooded, but not less than 20 s. G.1.9 Control The means of control of any such fixed gas fire extinguishing system shall be readily accessible and simple to operate and shall be located in a release box in a safe area outside the protected space. Two controls shall be provided, one for opening the distribution valve and one for opening the CO 2 gas cylinders. G.1.10 Ventilation Means shall be provided for stopping automatically all ventilation fans and closing openings serving the protected spaces, before the medium is released. G.1.11 Arrangement plan A general arrangement plan has to be exhibited in the Control Centre, the operating stations and the CO 2 rooms, showing the arrangement of the CO 2 system. G.1.12 Warning signs Warning signs shall be displayed at the accesses to the CO 2 room and to spaces protected by the system. G.1.13 Tests After completion of the system, pressure and tightness tests in acc. to an applicable standard used for the design of the system and free passage tests have to be performed. G.2 Extinguishing systems using gases other than CO 2 G.2.1 General G.2.1.1 Systems using extinguishing gases other than CO 2 shall be type approved in accordance with a standard acceptable to GL. G.2.1.2 No fire extinguishing gas shall be used which is carcinogenic, mutagenic or teratogenicity at concentrations expected during its use or which is not considered to be environmentally acceptable. No fire extinguishing gas shall be used in concentrations greater than the cardiac sensitization level NOAEL (No Observed Adverse Effect Level), without the use of the release arrangements and alarms as provided in G.2.6. In no case an extinguishing gas is permitted to be used in concentrations above its LOAEL (Lowest Observed Adverse Effect Level) nor its ALC (Approximate Lethal Concentration). G.2.1.3 New installations of halogenated hydrocarbon (halon) systems are not permitted. G.2.1.4 For systems using halocarbon clean agents the system shall be designed for a discharge of 95 % of the design concentration in not more than 10 s. For systems using inert gases, the discharge time shall not exceed 120 s for 85 % of the design concentration. Edition 2013 Germanischer Lloyd Page 8–9
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(IV-7-3) General Safety

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