Section 11 System arrangement requirements

11.1.2 The BWTS is to be provided with a by-pass and isolation or override arrangement to effectively isolate it from the ship’s ballast system and any essential ship system to which it is connected. The arrangement of the by-passes or overrides of the BWTS is to be consistent with the Operation Maintenance and Safety Manual approved by the Flag Administration during Type Approval.

11.1.3 The by-pass and isolation arrangements are to meet the electrotechnical requirements of Pt 5, Ch 25, 9.1 General as applicable.

11.1.4 When it is required to have an automatic shutdown of the BWTS for safety reasons, this must be as per Pt 5, Ch 25, 9.1 General 9.1.2.

11.1.5 Under normal operating conditions of ballasting and de-ballasting given in the Ballast Water Management Plan (BWMP), the adequacy of the generating plant capacity installed on the vessel is to be demonstrated by an electrical load analysis. For retrofit installation on existing ships, a revised electrical load analysis with preferential trips of non-essential services can be accepted.

11.1.6 The BWTS is to be operated in accordance with the requirements specified in the Type Approval Certificate (TAC) issued by the Flag Administration.

11.1.7 The BWTS is to be operated within its Treatment Rated Capacity (TRC) as specified in the TAC. This may require limiting of the ship’s ballast pump(s) flow rate. In case the maximum capacity of the ballast pump(s) exceeds the maximum TRC of the BWTS specified in the TAC issued by the Flag Administration, there is to be a limitation in the BWMP giving a maximum allowable flow rate for operating the ballast pump(s) that shall not exceed the maximum TRC of the BWTS.

11.1.8 The BWTS’s components including pressure vessels, piping Class I or II, filters and switchboards, section boards and distribution boards are required to be designed, constructed and tested and certified as per relevant requirements of LR Rules.

11.1.9 Where a vacuum or overpressure may occur in the ballast piping or in the ballast tanks due to the height difference or injection of inert gas or nitrogen (N₂), a suitable protection device is to be provided (i.e. P/V valves, P/V breakers, P/V breather valves, pressure safety relief valves or high/low pressure alarms).

The pressure and vacuum settings of the protection device are not to exceed the design pressure of the ballast piping (BWTS categories 3a and 3b) or ballast tank (BWTS categories 3a, 3b and 3c), as applicable.

For BWTS categories 3a, 3b and 3c, the inert gas or nitrogen product enriched air from the inert gas system and from the protection devices installed on the ballast tanks (i.e. P/V valves, P/V breakers or P/V breather valves) is to be discharged to a safe location*(1) and (2) (see Pt 5, Ch 25, 1.2 Definitions) on the open deck.

11.1.10 When the ballast tanks are considered hazardous areas, the hazardous area is to include the outlet of the protection devices: with reference to Pt 6, Ch 2, 14.2 Hazardous areas 14.2.5 the areas on the open deck, or semi-enclosed spaces on the open deck, within 1,5 m of their outlets are to be categorised hazardous Zone 1 and with reference to Pt 6, Ch 2, 14.2 Hazardous areas 14.2.6, an additional 1,5 m surrounding the 1,5 m hazardous Zone 1 is to be categorised hazardous Zone 2. Any source of ignition such as anchor windlass or opening into chain locker is to be located outside the hazardous areas. Further requirements of Pt 6, Ch 2, 14.2 Hazardous areas 14.2.5 are to be complied with as applicable.

11.1.12 Electric and electronic components are not to be installed in a hazardous area unless they are of certified safe type for use in the area. Cable penetrations of decks and bulkheads are to be sealed when a pressure difference between the areas is to be maintained. (See also Pt 6, Ch 2, 14.5 Installation of electrical equipment and Pt 6, Ch 2, 14.9 Cable and cable installation.)

11.1.13 Inert gas systems installed for de-oxygenation BWTS (categories 3a, 3b, 3c and 8) are to be designed in accordance with the following requirements:

1. International Code for Fire Safety Systems (FSS Code), Ch 15 Inert Gas Systems requirements
   • Inert gas system and Gas-safe space are defined in 2.1.2, 2.1.3;
   • for all inert gas systems, the general requirements of sections 2.2.1.3, 2.2.1.4, 2.2.2.1, the safety measures as per 2.2.2.2, 2.2.2.3, 2.2.2.6, indicators and alarms as per 2.2.4.1 to 2.2.4.5 with the exception of clauses 2.2.4.5.1.3 and 2.2.4.5.3;
   • for flue gas and inert gas generator systems, the system requirements of sections 2.3.1.1.2, 2.3.1.2, 2.3.1.4.2, 2.3.1.5, 2.3.1.6 with the exception of clause 2.3.2.2.1;
   • for nitrogen generator systems, the system requirements 2.4.1.3, 2.4.1.4 and 2.4.2.
   1. For inert gas systems installed for in-tank de-oxygenation BWTS (category 8): the requirements of 2.2.3.1, 2.2.3.2 except 2.2.3.2.6, 2.2.3.2.7 and 2.2.3.2.10.
      In general, when applying FSS Code Ch 15 requirements to inert-gas based BWTS, the following modifications are to be considered:

      • The terms ‘cargo tank’ and ‘cargo piping’ are to be replaced by ‘ballast water tank’ or ‘ballast water piping’ as relevant;
      • The term ‘cargo control room’ is to be replaced by ‘BWTS control station’ as relevant;
      • Requirements for slop tanks on combination carriers are to be disregarded;
      • When applying FSS Code 15.2.2.4.5.1.1, the acceptable oxygen content is to be specified by the manufacturer. 5 per cent oxygen content need not necessarily be applied.
2. Pt 5, Ch 15, 7 Inert gas systems on Tankers of 8,000 tonnes DWT and above as applicable. The terms ‘cargo tanks’ and ‘cargo piping’ are to be understood as ‘ballast tanks’ and ‘ballast piping’ respectively. For de-oxygenation BWTS (categories 3a, 3b, 3c and 8), the requirements in Pt 5, Ch 25, 11.1 General requirements 11.1.13.(a) prevail.

11.1.14 When cavitation is the BWTS treatment process or part of the BWTS treatment process, the design and the wall thickness or grade of materials or inside coating or surface treatment of the part of the piping where the cavitation is taking place is to be specifically considered.

11.2.1 Hazardous area classification is to be in accordance with Pt 6, Ch 2, 14.2 Hazardous areas.

11.2.2 BWTS using ozone generators (categories 7a and 7b) and de-oxygenation BWTS using inert gas generator with treated flue gas from main or auxiliary boilers or gas from an oil or gas-fired gas generator (categories 3b and 3c) are to be located outside the cargo area in accordance with Section 2.3.1.1.2 of FSS Code Ch 15. This requirement does not apply to inert gas generators for which FSS Code Ch 15/2.4.1 and Pt 5, Ch 15, 7 Inert gas systems on Tankers of 8,000 tonnes DWT and above.

11.2.4 In case two independent BWTS systems are not fitted, one for ballast tanks located within the cargo area and the other one for ballast tanks located outside thw cargo area, non-hazardous areas are not to be rendered hazardous by the use of the BWTS or its connections with the ballast system. Specific arrangements where only one single in-line BWTS (categories 1, 2, 3a, 3b, 4, 5, 6, 7a and 7b) could be accepted are given in Section 13.

11.2.5 The transfer of ballast water from hazardous to non-hazardous areas is not permitted except for sampling, see Pt 5, Ch 25, 11.2 Additional requirements for tankers 11.2.7. Ballast arrangements on ships carrying liquefied gases in bulk will be subject to special consideration.

11.2.6 Isolation between the ballast piping serving the ballast tanks inside the cargo area and that serving the ballast tanks outside the cargo area is to be in accordance with the following requirements:

1. Interconnection between the ballast piping serving the ballast tanks located within the cargo area and the ballast piping serving the ballast tanks located outside the cargo area may be accepted if an appropriate isolation arrangement is provided.
2. The means of appropriate isolation described in Pt 5, Ch 25, 11.2 Additional requirements for tankers 11.2.6.(c) is necessary for the interconnection in the case of active substance piping such as N₂ gas piping, inert gas piping, neutraliser piping, fresh water piping for filter cleaning, compressed air piping for remaining water purge and sea water piping for adjusting the salinity, etc. regardless of the diameter of the piping. For active substance piping and neutraliser piping (both up to DN50) only, alternative isolation arrangements, preferably on the open deck, offering equivalent safety and gas tightness may be considered for penetration of the bulkhead separating the non-hazardous machinery space from a hazardous area (such as the cargo pump-room) at as high an elevation in the machinery space as possible, preferably just below the main deck. The arrangements are to provide suitable protection measures in addressing the pollution hazards and safety concerns due to the potential migration of hydrocarbons or flammable or toxic liquids or vapours from the hazardous areas.

   The means of appropriate isolation described in Pt 5, Ch 25, 11.2 Additional requirements for tankers 11.2.6.(c) need not be applied to the sampling lines described in Pt 5, Ch 25, 11.2 Additional requirements for tankers 11.2.7.

3. The means of appropriate isolation is to be one of the following:
   1. Two non-return valves with positive means of closing in series with a spool piece (also mentioned ‘means of dis-connection’ in Annex I); or

      

      Note As an alternative to positive means of closure, an additional valve having such means of closure may be provided between the non-return valve and the spool piece.
   2. Two non-return valves with positive means of closing in series with a liquid seal at least 1,5 m in depth; or

      

      Note As an alternative to positive means of closure, an additional valve having such means of closure may be provided between the non-return valve and the liquid seal.

      Note 2. For ships operating in cold weather conditions, freeze protection should be provided in the water seal. A portable heating system can be accepted for this purpose.
   3. Automatic double block and bleed valves and a non-return valve with positive means of closing.

      

      Note . As an alternative to positive means of closure, an additional valve having such means of closure may be provided after the non-return valve.
4. The above-mentioned means of appropriate isolation in Pt 5, Ch 25, 11.2 Additional requirements for tankers 11.2.6.(c) is to be provided on the open deck in the cargo area.
   Note 1. When the fore peak tank is ballasted with the piping system serving the other ballast tanks within the cargo area, the means of appropriate isolation Pt 5, Ch 25, 11.2 Additional requirements for tankers 11.2.6.(c) and Pt 5, Ch 25, 11.2 Additional requirements for tankers 11.2.6.(d) are not required in-between the fore peak tank and the common ballast water piping serving the other ballast water tanks within the cargo area.

11.3.1 Where the operating principle of the BWTS involves the generation of a dangerous gas, the following requirements are to be satisfied:

1. Gas detection in spaces: Gas detection equipment is to be fitted in the spaces where dangerous gas could be present, and an audible and visual alarm is to be activated both locally and at the BWTS control station in the event of leakage.

   The gas detectors are to be located as close as possible to the BWTS components where the dangerous gas may accumulate.

   For flammable gases and explosive atmosphere including but not limited to hydrogen, the construction, testing and performance of the gas detection devices is to be in accordance with IEC 60079-29-1, IEC 60079-29-2, IEC 60079-29-3 and/or IEC 60079-29-4, as applicable.

   Where other hazards are considered, such as toxicity, asphyxiation, corrosive and reactivity hazards, a recognised standard acceptable to LR is to be selected with due consideration of the specific gases to be detected and due consideration of the performance of the detection device with regards to the specific atmosphere where it is used.

2. Oxygen sensors: In spaces where inert gas generator systems are fitted (BWTS categories 3b and 3c) or nitrogen generators are fitted (BWTS categories 3a and 8), at least two oxygen sensors are to be positioned at appropriate locations (as required by paragraph 2.2.4.5.4 of Chapter 15 of the FSS Code as amended by IMO resolutions up to MSC.410(97)) to trigger an alarm when the oxygen level falls below 19 per cent. The alarms are to be both audible and visual and are to be activated inside the space, at the entry into the space and inside the BWTS control station.

   For BWTS categories 7a and 7b, at least two oxygen sensors are to be positioned at appropriate locations in the following spaces. Spaces where ozone generators are fitted; spaces where ozone destructors are fitted; or spaces where ozone piping is routed to trigger an alarm when the oxygen level rises above 23 per cent. The alarms are to be both audible and visual and are to be activated inside the space, at the entry into the space, and inside the BWTS control station.

   Automatic shutdown of the BWTS is to be arranged when the oxygen level rises above 25 per cent. Audible and visual alarms independent from those specified in the preceding paragraph are to be activated prior to this shutdown.

3. Ozone sensors: For BWTS categories 7a and 7b, at least one ozone sensor is to be provided in the vicinity of the discharge outlet to the open deck from the ozone destructors addressed in Pt 5, Ch 25, 1.2 Definitions 1.2.5 to trigger an alarm when the ozone concentration level rises above 0,1 ppm. The alarm is to be both audible and visual and is to be activated in the BWTS control room. In addition, at least two ozone sensors are to be positioned at appropriate locations in the following spaces: spaces where ozone generators are fitted; spaces where ozone destructors are fitted; or spaces where ozone piping is routed.

   These sensors are to trigger an alarm when the ozone concentration level rises above 0,1 ppm. The alarms are to be both audible and visual and shall be activated at the following locations: inside the space; at the entry into the space; and inside the BWTS control room.

   Automatic shutdown of the BWTS is to be arranged when the ozone concentration measured from any one or both of the two sensors inside the space rises above 0,2 ppm.

4. Gas detection in double walled pipes or pipe ducts: Inside double walled spaces or pipe ducts required by Pt 5, Ch 25, 11.3 Special requirements for BWTS generating dangerous gas or dealing with dangerous liquids (categories 2, 3a, 3b, 3c, 4, 5, 6, 7a, 7b and 8) 11.3.2.(a).(i), sensors are to be provided for the detection of hydrogen leakages (BWTS categories 4, 5 and 6 when relevant) or oxygen leakages (BWTS categories 7a and 7b) or ozone leakages (BWTS categories 7a and 7b). The sensors are to activate an alarm at the high concentration level settings and automatic shutdown of the BWTS at the high-high concentration level settings described in Pt 5, Ch 25, 11.3 Special requirements for BWTS generating dangerous gas or dealing with dangerous liquids (categories 2, 3a, 3b, 3c, 4, 5, 6, 7a, 7b and 8) 11.3.1.(a) to Pt 5, Ch 25, 11.3 Special requirements for BWTS generating dangerous gas or dealing with dangerous liquids (categories 2, 3a, 3b, 3c, 4, 5, 6, 7a, 7b and 8) 11.3.1.(c).
   Note As an alternative to the sensor for the gas detection, monitored under-pressurisation inside the double walled spaces or pipe ducts may be provided with an alarm and automatic shutdown of the BWTS in case of loss of the under-pressurisation. This may be achieved by monitoring the pressure inside the double walled spaces or pipe ducts.
5. Hydrogen: For in-line full flow electrolysis BWTS (category 4), in-line side-stream electrolysis BWTS (category 5) and in-line injection BWTS using a chemical which is stored on board (category 6): the hydrogen de-gas arrangement (when provided) is to be provided with redundant ventilation fans and redundant monitoring of the ventilation system.

   In addition, the ventilation fan is to be certified explosion proof and have a spark arrestor to prevent ignition sources entering the ventilation system where hydrogen may be present in explosive concentrations.

   Audible and visual alarms and automatic shutdown of the BWTS are to be arranged for respectively high and high-high levels of hydrogen concentration. The open end of the hydrogen by-product enriched gas relieving device is to be led to a safe location*(3) (see Pt 5, Ch 25, 1.2 Definitions) on the open deck.

6. Vents: The open ends of the inert gas or nitrogen gas enriched air (BWTS categories 3a, 3b, 3c and 8) or oxygen-enriched air vent pipes (BWTS categories 3a, 7a, 7b and 8) are to be led to a safe location*(1) and (2) (see Pt 5, Ch 25, 1.2 Definitions) on the open deck.

11.3.3 For BWTS using chemical substances or dangerous gases which are stored on board for either:

• storage or preparation of the active substances (BWTS categories 2 and 6);
• storage or preparation of the neutralisers (BWTS categories 4, 5, 6, 7a and 7b); or
• recycling the wastes produced by the BWTS (BWTS category 2);
  handling procedures are to be in accordance with the Material Safety Data Sheet and BWM.2/Circ.20 Guidance to ensure safe handling and storage of chemicals and preparations used to treat ballast water and the development of safety procedures for risks to the ship and crew resulting from the treatment process, and the following measures are to be taken as appropriate:

  1. The materials or inside coating used for the chemical storage tanks, piping and fittings are to be resistant to such chemical substances.
  2. Chemical substances (even if they are not defined as dangerous according to Pt 5, Ch 25, 1.2 Definitions) and gas storage tanks are to be designed, constructed, tested, inspected, certified and maintained in accordance with:
     • for independent tanks permanently fixed on board containing dangerous liquids (e.g. sulphuric acid, H₂SO₄) or dangerous gas (e.g. oxygen, O₂) the LR Rules for pressure vessels of Class I or II as applicable, see Pt 5, Ch 11 Other Pressure Vessels;
     • for independent tanks permanently fixed on board not containing dangerous liquids (e.g. sodium sulphite, sodium biosulphite or sodium thiosulfphate neutralisers) and not containing dangerous gas (e.g. nitrogen, N₂): the Classification Rules or other industry standard recognised by the Classification Society;
     • for portable tanks: the IMDG Code or other industry standard recognised by the Classification Society;
     • Atmospheric storage tanks will be considered for non-hazardous and non-toxic chemicals not requiring inert gas blanketing and with negligible vapour pressure.
  3. When the chemical substances are stored inside integral tanks, the ship's shell plating is not to form any boundary of the tank.
  4. Dangerous liquids and dangerous gas storage tank air pipes are to be led to a safe location*(1) and (2) (see Pt 5, Ch 25, 1.2 Definitions) on the open deck.
  5. An operations manual containing chemical injection procedures, alarm systems, measures in case of emergency, etc. is to be provided and kept on board.
  6. Dangerous liquid storage tanks and their associated components, such as pumps and filters, are to be provided with spill trays or a secondary containment system of sufficient volume to contain potential leakages from tank openings, gauge glasses, pumps, filters and piping fittings.

Further to the safety and/or pollution assessment of the concerned chemical substances, consideration is to be provided for segregation of the drains from such spill trays (or secondary containment system) or piping systems from the engine room bilge system or from the cargo pump-room bilge system, as applicable. When necessary, arrangement is to be provided within the spill trays (or within the secondary containment system) for the detection of dangerous liquid or dangerous gas as defined respectively in Pt 5, Ch 25, 1.2 Definitions.