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Gas detection and entryLesson 4 of 6

Fixed gas detection on tankers, gas carriers and in pump-rooms

You will know which fixed gas detection each tanker type must have, where it samples, when it must alarm, and how it is tested and kept in service.

15 minutes · For signed-up learners, free · Rules checked 20 October 2026

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Portable meters protect the person about to enter a space. Fixed systems watch spaces nobody is in: the cargo pump-room at the bottom of the ship, the ballast tanks and voids wrapped around the cargo, the hold spaces and interbarrier spaces of a gas carrier. A leak there gives no warning until vapour finds an ignition source or a crew member opens the door.

SOLAS answered these risks in two steps: continuous hydrocarbon monitoring for tanker cargo pump-rooms came with the revised chapter II-2 in force from 1 July 2002 (and was required on older tankers by 1 July 2005 at the latest), and fixed detection in the double hulls of new large oil tankers from 1 January 2012. This lesson sets out what each tanker type must have, how it must alarm, and how the crew and service technicians keep it honest.

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In this lesson

  • Try it: Which rule does each requirement come from?
  • In plain words
  • In detail
  • What the rules say
  • Flag and class notes
  • Key numbers
  • What inspectors find
  • Questions people ask
  • Quiz: 5 questions

Sources

  1. 1 IMO Resolution MSC.99(73), Amendments to SOLAS (adopted 5 December 2000, in force 1 July 2002), Annex, revised chapter II-2, regulation 1 paragraph 6.7 and regulation 4 paragraph 5.10. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.99(73).pdf
  2. 2 IMO Resolution MSC.291(87), Amendments to SOLAS (adopted 21 May 2010, in force 1 January 2012), Annex, regulation II-2/4 paragraph 5.7. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.291(87).pdf
  3. 3 IMO Resolution MSC.292(87), Amendments to the International Code for Fire Safety Systems (adopted 21 May 2010), Annex, new chapter 16, Fixed hydrocarbon gas detection systems, paragraphs 1.2 to 2.2.3.4. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.292(87).pdf
  4. 4 IMO Resolution MSC.370(93), Amendments to the IGC Code (adopted 22 May 2014; applies to gas carriers constructed on or after 1 July 2016), Annex, section 13.6. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.370(93).pdf
  5. 5 IMO Resolution MSC.176(79), 2004 amendments to the IBC Code (adopted 10 December 2004, in force 1 January 2007), Annex, section 13.2. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.176(79).pdf
  6. 6 IMO MSC/Circ.1037, Unified interpretations of the revised SOLAS chapter II-2 (28 May 2002), Annex, regulation 4.5.10. Copy published by Traficom: https://www.traficom.fi/files/media/regulation/22659-MSC_1-Circ_1037_-_tulkinta_revised_SOLAS_chapter_II-2.pdf
  7. 7 Republic of the Marshall Islands Maritime Administrator, Marine Notice 7-041-1, Entering enclosed spaces: safety precautions (Rev. Jan/2026), section 4. https://www.register-iri.com/wp-content/uploads/MN-7-041-1.pdf
  8. 8 IMO MSC.1/Circ.1527, Unified interpretations of SOLAS chapter II-2 (6 June 2016), Annex, regulation II-2/4.5.7.3.1, as published by the Marine Department of Hong Kong. https://www.mardep.gov.hk/en/msnote/pdf/msin1660anx1.pdf
  9. 9 IACS Unified Interpretation SC272, Inert gas supply to double-hull spaces (SOLAS II-2/4.5.5.1), December 2015, copy published by Türk Loydu. https://www.turkloydu.org/pdf-files/iacs-karar-ve-csr-degisimleri/iacs-es-yorumlari/UI_SC272.pdf

Free awareness training. Al Safwan Marine is not an approved training provider, so no certificate is given, and these courses are not a qualification. They don't replace STCW training, manufacturer training or the certification technicians need for this work. The manufacturer's manual and your flag's rules always come first.

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