What are Class of bulkhead as per SOLAS ?

Class A

  • Are divisions forming bulkheads and decks that are;
    • Constructed of steel or equivalent
    • suitably stiffened
    • Prevent passage of smoke and flame to the end of one hour standard fire test
    • Insulated using non-combustible material so that average temperature on un-exposed side does not rise above 139oC and point temperature above 180o The time duration for which the bulkhead complies with this , governs its class
      A-60— 60 Min
      A-30— 30 Min
      A-15 —15 Min
      A-0 —0 Min

Class B

  • These are divisions formed by bulkheads, decks, ceilings and lining
    • Prevent passage of flame for first half hour of standard fire test
    • Insulated so average un-exposed side temperature does not rise more than 139oC above original and no single point rises more than 225oC above original .
    • B-15 -15 Min
      B-0 -0 Min
    • Constructed of non-combustible material and all materials entering the construction are similarly non-combustible except where permitted.

Class C

  • These are divisions constructed of approved non-combustible materials. Combustible veneers are allowed where they meet other criteria
  • Main vertical zones Divided by Class A bulkheads and not exceeding 40m in length
You may also know :
  • Transverse Bulkheads serve to :
  • Subdivide a ship against flooding and spread of fire
  • Support Decks & Superstructures
  • Resist racking stresses
  • “Margin line” means a line drawn at least 76mm below the upper surface of the bulkhead deck at the side of a ship, and assumed for the purpose of determining the floodable length of the ship
  • Bulkhead Deck :
  • It is usually the freeboard deck
  • For Collision Bulkhead it is the uppermost continuous deck
  • For Afterpeak Bulkhead it may be one deck above load water line, provided this deck is made watertight to the stern or to a watertight transom floor.


About the author

Manish Mayank

Graduated from M.E.R.I. (Mumbai). A cool, calm, composed and the brain behind the development of the database. The strong will to contribute in maritime education and to present it in completely different and innovative way is his source of inspiration.


  • Please do correction for class A
    …average temperature of the unexposed side does not rise above 140C of the original temperature, nor will the temperature at any point including a joint rise above 180C above original temperature.

  • Plz edit.

    Collision bulkhead definition and freeboard definition.

    Very useful notes. Thanks very much.

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