IMO Unifies SOLAS Convention Regulations

The International Maritime Organization (IMO) has issued Circular providing unified interpretations of SOLAS regulation XII/6.5.1, in relation to the protection of cargo holds from loading and discharge equipment, and regulation XII/6.5.3, regarding failure of cargo hold structural members and panels. Member Governments and international organizations are invited to use the annexed unified interpretations as guidance when applying relevant provisions of SOLAS chapter XII to bulk carrier construction, for ships constructed on or after 1 July 2006, and to bring the unified interpretations to the attention of all parties concerned.

Regulation XII/6.5.1 – Protection of cargo holds from loading/discharge equipment:

• The protection of the structure of the cargo holds should be achieved by structural design features such as mandatory application of classification society “grab notation”.
• The protection of hatchways and coamings from grab wire damage may be achieved by fitting protection bars (e.g., half-round bar) on the hatch-side girder (e.g., upper portion of top-side tank plates), hatch-end beams and the upper portion of hatch coamings.

Regulation XII/6.5.3 – Failure of cargo hold structural members and panels:

• Stiffening structural member means a stiffener attached to a structural plating panel.
• For the purpose of this interpretation, cargo area includes hatchway coamings, top-side tanks, side shells, longitudinal bulkheads of double-side skin construction, bilge hopper tanks and double bottom, but excludes hatchway covers.
• Structural members of a cargo hold are the hatchway coamings, transverse bulkheads, panel plates of the top-side tanks and bilge hopper tanks facing the cargo hold, inner bottom, side shell of single-side skin construction or longitudinal bulkhead of double-side skin construction.
• The term “single failure of one stiffening structural member” is generally considered to mean localized mechanical damage such as local permanent deformation, cracking or weld failure that might result from accidental damage within the cargo hold.
• The design considerations should be such that a single localized damage, which is of a size that is likely to be detected, should not lead to complete collapse of the stiffened panel under a load equal to the maximum allowable design still water load plus 80% of the maximum lifetime dynamic load.
• If the damage is a crack or welding damage, immediate fracture propagation should be avoided; This may be achieved by appropriate design and selection of materials.
• The intent of the regulation regarding the external hull envelope within the cargo area is addressed through the structural design requirements that meet the environmental and operational loads defined in the relevant requirements of classification societies.

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