IMO revises Guidelines for the approval of fixed dry chemical powder fire-extinguishing systems for the protection of ships carrying liquefied gases in bulk

The International Maritime Organization has revised the Guidelines for the approval of fixed dry chemical powder fire-extinguishing systems for the protection of ships carrying liquefied gases in bulk.

This circular has been issued on December 5th, 2022.

The Maritime Safety Committee, at its eighty-sixth session (27 May to 5 June 2009), having considered the proposal by the Sub-Committee on Fire Protection, at its fifty-third session, approved Guidelines for the approval of fixed dry chemical powder fire-extinguishing systems for the protection of ships carrying liquefied gases in bulk (MSC.1/Circ.1315).  

The Committee, at its 106th session (2 to 11 November 2022), approved the Revised guidelines for the approval of fixed dry chemical powder fire-extinguishing systems for the protection of ships carrying liquefied gases in bulk (MSC.1/Circ.1315/Rev.1), prepared by the Sub-Committee on Ship Systems and Equipment, at its eighth session (28 February to 4 March 2022), as set out in the annex.  

Member Governments are invited to apply the annexed Revised Guidelines for the approval of fixed dry chemical powder fire-extinguishing systems installed on or after 1 July 2023 for the protection of ships carrying liquefied gases in bulk, and bring them to the attention of ship designers, shipowners, equipment manufacturers, test  laboratories and other parties concerned.

The expression "installed on or after 1 July 2023" means:

• for ships for which the building contract is placed on or after 1 July 2023, or in the absence of the contract, constructed on or after 1 July 2023, any installation date on the ship; or
• for ships other than those ships prescribed in paragraph above, a contractual delivery date for the equipment or, in the absence of a contractual delivery date, the actual delivery date of the equipment to the ship on or after 1 July 2023.

This circular supersedes MSC.1/Circ.1315.

Existing fixed dry chemical powder fire-extinguishing systems for the protection of ships carrying liquefied gases in bulk approved based on MSC.1/Circ.1315 and installed before 1 July 2023 should be permitted to remain in service as long as they are serviceable.

Annex

1 Application

These Revised Guidelines apply to fixed dry chemical powder fire-extinguishing systems for the protection of on-deck cargo areas of ships carrying liquefied gases in bulk in accordance with SOLAS regulation II-2/1.6.2 and chapter 11 of the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code).

2 Definitions  

2.1 Caking is a chemical reaction between dry chemical powder and moisture that causes individual particles of the medium to bind together to form an aggregate mass.

2.2 Dry chemical powder is an extinguishing medium composed of finely divided solid chemical products consisting of one or more components, which may be combined with additives to improve its characteristics to prevent packing and caking (moisture absorption) and to ensure consistent flow characteristics.  

2.3 Dry chemical powder unit is a complete system including dry chemical storage container(s), pressurizing gas storage container(s), controls, piping and hand hose lines.  

2.4 Gas point is a defined point in the discharge of a dry chemical powder unit when the discharge of dry chemical powder ends, and is marked by a change in the nozzle stream to the discharge of primarily pressurizing gas.  

2.5 Hand hose line is a hand-held dry chemical powder nozzle covering cargo areas not covered by a monitor, that is normally closed and opened by the individual operating the device at or just before the nozzle.  

2.6 Monitor is a fixed dry chemical powder nozzle protecting cargo loading and discharge manifold areas.  

2.7 Packing is a phenomenon that occurs when dry chemical powder stored in a container is subjected to vibration causing the smaller particles to move to the bottom of the container and the larger particles to travel to the top.  

2.8 Pressurizing medium is the gas used to expel the dry chemical from the system, usually dry nitrogen.  

3 Principal requirements for the dry chemical powder and the system  

3.1 The system should be capable of manual release. A manual release station should be located adjacent to each hand hose line and each monitor. A back-up release station should be provided at the fixed dry chemical powder unit. The operation of any manual release station should initiate the pressurization of the fixed dry chemical powder unit and begin the discharge of dry chemical powder to all connected hand hose lines and monitors.

3.2 The system and its components should be designed to withstand ambient temperature changes, vibration, humidity, shock, impact and corrosion normally encountered on the open deck of ships, and manufactured and tested to the satisfaction of the Administration, in accordance with the criteria given in the appendix.  

3.3 Dry chemical storage should be designed to maintain the conditions on board in accordance with the manufacturer's recommendations.

3.4 Systems should be designed for the discharge characteristics and flow rates of a specific dry chemical powder medium (formulation and physical nature of composition). The specific type of dry chemical powder medium in the system should not be changed unless testing to verify performance is conducted by a laboratory to the satisfaction of the Administration. Different dry chemical powder media should not be mixed.  

3.5 Dry chemical storage containers should be designed to pressure codes  of practice acceptable to the Administration, for the maximum system pressure developed at 55ºC.  

3.6 Dry chemical powder should be tested as specified in the appendix.  

3.7 A means for pressurizing the system using an inert gas, which is normally dry nitrogen, in high pressure cylinders should be provided. The inert gas should be industrial grade with a dew point of -50ºC or lower. Pressure gauges should be provided for monitoring the  contents of the cylinders. A pressure regulator should be installed to reduce the gas pressure to the required system operating pressure.  

3.8 The quantity of expellant gas should be adequate for the system to discharge the entire charge of dry chemical powder within the time period specified in paragraph 1 of the appendix. If multiple gas cylinders are provided, they should be arranged with normally closed cylinder valves that are automatically opened by a pilot system when a release station is actuated. Each cylinder should have, in addition, the capability of manual operation.

3.9 System piping should be arranged to ensure that the required flow rates are achieved at each hand hose line and monitor. Flow through the piping should be based on flow calculation methods determined by the test laboratory for the specific dry chemical powder medium and equipment used.  

3.10 Hand hose line nozzles, monitors and hose couplings should be constructed o brass or stainless steel. Piping, fittings and related components, except gaskets, should be designed to withstand 925ºC.  

3.11 Dry chemical storage container pick-up tubes and related internal structures should be shown to be resistant to corrosive effects of the dry chemical medium.

3.12 Dry chemical storage containers should have a fill opening of at least 100 mm to allow onboard recharging and suitable connections to allow the dry powder charge to be fully agitated with nitrogen, in accordance with the system manufacturer's maintenance instructions.  

3.13 Operating instructions for the system should be placed at each operating station.  

3.14 Recharging instructions should be provided on a permanent nameplate affixed to the fixed dry chemical powder unit. As a minimum, the instructions should indicate the required type of dry chemical powder, the manufacturer of the powder and the required charge. The required pressurizing medium pressure, number of cylinders and regulator valve setting should also be provided.

3.15 An approved design, installation, operation and maintenance manual should be provided to the shipowner for each type of fixed dry chemical powder unit.  

4 Onboard testing  

After installation, the pipes, valves, fittings and assembled systems should be subjected to a tightness test and functional testing of the remote and local release stations.

Testing arrangements are to involve discharge using dry chemical powder from all monitors and hand hose lines on board, but a full discharge of the installed quantity of dry powder is not required.

This testing can also be used to satisfy the requirement that the piping is free of obstructions, in lieu of blowing through with dry air all the distribution piping.

However, after completion of this testing, the system, including all monitors and hand hose lines, are to be blown through with dry air; but only for the purpose of the system subsequently being clear from any residues of dry chemical powder.

Appendix

Approval tests

Except for paragraph 5, a fully charged fixed dry chemical powder unit conditioned at 21 ± 3ºC for at least 24 h should be used.  

Characteristics of the system  

1 Discharge duration test

A fixed dry chemical powder unit should have a discharge duration of at least 45 s with all attached hand hose lines and monitors operating. The hand hose lines should be fully deployed for this test.

To conduct the test, the hose lines and monitors should be held in a horizontal position and their discharge valves fully opened.

The duration of discharge should be measured from the time dry chemical powder begins flowing from all attached devices until the gas point is reached at the first nozzle.  

2 Maximum length of piping and fittings test  

The discharge duration test should be conducted with the maximum length of discharge piping, elbows, tees and other fittings to be used on board, as recommended by the manufacturer.

One nozzle should be located at the maximum height for which approval is requested.  

3 Discharge range test  

Dry chemical powder monitors should have a minimum discharge range as follows:  

Monitor flow rate   Minimum range  
10 kg/s     10 m  
25 kg/s     30 m  
45 kg/s     40 m  

For monitors with a discharge rate between the above listed values, the minimum range should be determined by interpolation. The test should be conducted with the monitor positioned, 1 metre above the floor. The monitor should be capable of achieving the minimum range for at least 40 s of the 45 s discharge.  

4 Flow rate test  

The minimum flow rate of each type of hand hose line nozzle should be at least 3.5 kg/s and each type of monitor should be at least 10 kg/s. The minimum flow rate should be determined based on the average of three discharge tests.

The tests should be conducted with the nozzle/monitor discharged for at least 30 s. The fixed dry chemical powder unit should be placed on a load cell or weighed before and after testing to determine the quantity of medium discharged during the test.  

5 Minimum temperature test

A fully charged fixed dry chemical powder unit conditioned at the minimum expected storage temperature for at least 24 h should be capable of discharging at least 85% of the dry chemical medium with all attached hand hose lines and monitors operating.

The minimum expected storage temperature should be determined by the Administration.

6 Hand hose line hydrostatic test  

A full-length representative sample of a hand hose line should be subjected to a hydrostatic pressure equal to two times the maximum operating pressure that would be developed in the line by a fully charged unit with the nozzle discharge valve closed.

The hose should be capable of withstanding this test pressure for a period of 1 min without rupturing.  

7 Salt spray test  

7.1 Representative samples of valves, pressure regulators, gauges, releasing controls and related components that will be installed at locations exposed to the weather should be subjected to a salt spray within a fog chamber. Prior to exposure, any components with inlet or outlet orifices should be sealed.  

7.2 The salt solution should be a 20% by mass sodium chloride solution in distilled water. The pH should be between 6.5 and 7.2 and the density between 1.126 g/mL and 1.157 g/mL when atomized at 35ºC. Suitable means of controlling the atmosphere in the chamber should be  provided. The specimens should be supported in their normal operating position and exposed to the salt spray (fog) in a chamber having a volume of at least 0.43 m3 in which the exposure zone should be maintained at a temperature of 35 ± 2ºC. The temperature should be recorded at least once per day, at least 7 h apart (except weekends and holidays when the chamber normally would not be opened). Salt solution should be supplied from a recirculating reservoir through air-aspirating nozzles, at a pressure between 0.7 bar (0.07 MPa) and 1.7 bar (0.17 MPa). Salt solution run-off from exposed samples should be collected and should not return to the reservoir for recirculation. The samples should be shielded from condensate dripping.  

7.3 Fog should be collected from at least two points in the exposure zone to determine the rate of application and salt concentration. The fog should be such that for each 80 cm2 of collection area, 1 mL to 2 mL of solution should be collected per hour over a 16 h period and the salt concentration should be 20 ± 1% by mass.  

7.4 The samples should withstand exposure to the salt spray for a period of 30 days. After this period, the samples should be removed from the fog chamber and allowed to dry for 4 to 7 days at a temperature of 20°C to 25°C in an atmosphere having a relative humidity not greater than 70%.  

7.5 Following the drying period, the samples should be examined for evidence of failure. Any operating components should be functionally tested to verify continued operability. Gauges should remain watertight for at least 2 h when immersed in 0.3 m of water.  

Characteristics of the dry chemical powder  

8 Temperature test  

Dry chemical powders should be tested at a temperature of 55°C or higher.  

9 Dry chemical powder tests  

Dry chemicals should be tested in accordance with ISO 7202:2018, as amended by paragraph 8 above.

10 Characteristics of the fire test  

The dry chemical powder should be demonstrated capable of  extinguishing fires in liquefied gas cargoes.

Representative equipment should be subjected to full-scale fire tests to the satisfaction of the Administration. Fire test using heptane should be carried out in accordance with ISO 7202 standards, item 13.3.

10.1 Characteristics of fires to be extinguished during the fire test

10.1.1 The fire test should be conducted using heptane as outlined in section 8 of ISO 7165:2017 standards for a Class B fire, except as outlined in section 9 of the appendix to these Revised Guidelines.

10.1.2 The fire tests should be conducted in a controlled space/area with no restrictions on air supply with agreed standard test equipment. Wind speed should not exceed 3 m/s during the fire tests and oxygen concentration should not be lower than 20% throughout the fire test. The fire tests may be performed outside.

10.2 Establishment of acceptance criteria for extinguishment in the fire test

10.2.1  Test requirements:  

• .1  temperature: 0°C to +30°C;
• .2  powder application rate should be measured;
• .3  the design of the hand hose line (including the nozzle) should be determined by the manufacturer and recorded in the test report; the system installed on board should match the qualification tests and be in accordance with the minimum requirements of resolution MSC.370(93); and
• .4  10 second discharge time after extinguishment;

10.2.2  Test fire arrangement/apparatus:

• .1 design and capacity of the storage tank containing the powder should be specified; similar storage tank should be on board in accordance with these qualification tests;
• .2  operating pressure of the extinguishing system should be recorded;
• .3  size and length of the piping should be recorded; and
• .4  the design of the fixed monitor (including the nozzle) should be determined by the manufacturer and recorded in the test report; the system installed on board should match the qualification tests and be in accordance with the minimum requirements of resolution MSC.370(93).

10.2.3 The fire tray should be constructed in accordance with paragraph 8.4.3 of standard ISO 7165:2017. The dimensions of fire tray should be based on the class 144B test fire given in table 9 of standard ISO 7165:2017.

10.2.4  The following parameters should be measured and recorded:  

• .1 heptane volume for the fire scenario;  
• .2 the discharge pressures at the inlet of fixed monitor and at the hand hose, at the outlet of the dry chemical powder container and at the outlet of the pressurizing gas container;  
• .3 the mass of the dry chemical powder before and after the fire test; and
• .4 the time for extinction should be recorded for each test. The average time over all the tests performed is the extinction time.

10.2.5 Acceptance criteria:  

• .1 the fire should be extinguished;  
• .2 for any given configuration, the test should be performed three times out of which two should be  successful. The maximum used powder quantity necessary to extinguish the fire in the three tests is the quantity needed to extinguish the fire; and  
• .3 tests should be performed in such a way that they do not rely on skills of the fire-fighter operating the equipment and, therefore, a fixed monitor or hose line should be used.

10.2.6 Operation of the fire-fighting system during the tests:  

• .1 the fires should be extinguished within discharge time for the fire from the activation of the fixed dry chemical powder unit;
• .2 for the fire a re-ignition test should be carried out to demonstrate that not all the fuel has been consumed; and
• .3 the monitor or hose line should be discharged continuously. The operator may move but should attack the fire from one side of the pan only, which should be the side judged most difficult to extinguish the fire.

11 Approval of the fire-extinguishing system

1 The Type Approval Certificate for fire-extinguishing system should include at least the following:

• .1 allowable storage temperature lower and higher range for the system;
• .2 name of the specific dry chemical powder tested and approved with the system;
• .3 allowable storage time;
• .4 approved manufacturer's product manual; and
• .5 checking/analyses intervals.

12 Dry chemical powder storage  

Notwithstanding paragraph 8 above, the dry chemical powder should be tested for the expected maximum temperature to which it will be exposed during its storage on board and labelled accordingly.

RELEVANT DOCUMENTS (AVAILABLE ONLY TO SUBSCRIBERS):

REVISED GUIDELINES FOR THE APPROVAL OF FIXED DRY CHEMICAL POWDER FIRE-EXTINGUISHING SYSTEMS FOR THE PROTECTION OF SHIPS CARRYING LIQUEFIED GASES IN BULK

Amendments to the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code)