Regulation 59 - Venting, purging, gas-freeing and ventilation
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Regulation 59 - Venting, purging, gas-freeing and ventilation

Parent topic: Part D - Fire Safety Measures for Tankers

59.1.5 Reference to MSC/Circ.677 and MSC/Circ.450/Rev.1, and ullage openings

  • 1 Reference is made to MSC/Circ.677 - Revised standards for the design, testing and locating of devices to prevent the passage of flame into cargo tanks in oil tankers, and MSC/Circ.450/Rev.1 - Revised factors to be taken into consideration when designing cargo tank venting and gas-freeing arrangements.

  • 2 Ullage openings should not be used for pressure equalization. They should be provided with self-closing and tightly sealing covers. Flame arresters and flame screens are not permitted in these openings.

59.1.6 Use of spill valves and systems for guarding against liquid rising

  • 1 Spill valves will normally not be considered equivalent to an overflow system.

  • 2 The system for guarding against liquid rising to a height which would exceed the design head of cargo tanks should be independent of the gauging devices.

59.1.7.2 Electrical equipment in areas next to cargo tank ventilation outlets which permit flow of small volumes of vapour

 Permitted electrical equipment:

  • .1 Areas on open deck within 3 m of cargo tank ventilation outlets which permit the flow of small volumes of vapour caused by thermal variation:

    • certified safe type equipment.

  • .2 Areas 2 m beyond the zone specified in .1 above:

    • certified safe type equipment; or
    • equipment of a type which ensures absence of sparks or arcs and absence of ignition capable surface during normal operation; or
    • equipment specifically designed for zone 2.

59.1.9.3 Electrical equipment in areas next to cargo tank ventilation outlets which permit flow of large volumes of vapour, location of anchor windlass and chain locker openings and reference to IEC 92-502

  • 1 Permitted electrical equipment:

    • .1 Areas on open deck within 6 m of cargo tank ventilation outlets which permit the flow of small volumes of vapour during loading/discharging/ballast:

      • certified safe type equipment.

    • .2 Areas 4 m beyond the zone specified in .1 above:

      • certified safe type equipment; or
      • equipment of a type which ensures, absence of sparks or arcs and absence of ignition capable surface during normal operation; or
      • equipment specifically designed for zone 2.

  • 2 Anchor windlass and chain locker openings constitute ignition hazards. They should be located at the distance required by regulations II-2/59.1.7.2, 59.1.9.3 and 59.1.9.4.

  • 3 Electrical equipment fitted in compliance with IEC 92-502 is not considered a source of ignition or ignition hazard.

59.1.9.4 Location of anchor windless and chain locker openings and reference to IEC 92-502

  • 1 Anchor windless and chain lockers openings constitute ignition hazards. They should be located at the distance required by regulations II-2/59.1.7.2, 59.1.9.3 and 59.1.9.4.

  • 2 Electrical equipment fitted in compliance with IEC 92-502 is not considered a source of ignition or ignition hazard.

59.2 Location of outlets and reference to MSC/Circ.677 and MSC/Circ.450/Rev.1

  • 1 The outlets mentioned in regulation II-2/59.2 should be located in compliance with regulation II-2/59.1.9.3 as far as the horizontal distance is concerned.

  • 2 Reference is made to MSC/Circ.677 - Revised standards for the design, testing and locating of devices to prevent the passage of flame into cargo tanks in oil tankers, and MSC/Circ.450/Rev.1 - Revised factors to be taken into consideration when designing cargo tank venting and gas-freeing arrangements.

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