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 139^oC and point temperature above 180^o 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 139^oC above original and no single point rises more than 225^oC 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

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Purpose:

• Transverse Bulkheads serve to :
• Subdivide a ship against flooding and spread of fire
• Support Decks & Superstructures
• Resist racking stresses

Definitions

• “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.