Overview
ISO 5778:1998 - Ships and marine technology - Small weathertight steel hatches - defines standard dimensions, materials and manufacture quality for small weathertight steel hatches used on board ships. The standard ensures interchangeability of hatch covers intended for loading operations and access to storage compartments and dry cargo holds. It also requires compliance with applicable statutory rules (for example, the International Convention on Load Lines 1966, LLC66) and leaves non‑critical dimensions to the manufacturer.
Key topics and technical requirements
- Nominal sizes: Standard nominal sizes include 630×630, 630×830, 830×630, 830×830, 1030×1030 and 1330×1330 mm, based on inside coaming dimensions.
- Coaming and cover geometry: Upper coaming detail, corner shapes (square or rounded) and edge chamfering/rounding to protect the hatch seal.
- Cover plate: Specific cover plate dimensions with larger plates (>830×830 mm) requiring additional stiffening in line with Load Lines Regulation 16(2).
- Hatch seal: Resilient seal cross-section of 45×20 mm; initial compression allowed 2 mm and maximum compression limited to 4 mm using a depth stop.
- Fittings and fastenings:
- Two hinges per hatch with oval holes to allow seal compression.
- Closing devices using toggle bolts and wing nuts; wing nuts sized for single-person tightening without tools.
- Toggle bolt threads to conform to ISO 262 (metric screw thread sizes).
- Materials:
- Coamings, covers and primary fittings: weldable steel with minimum tensile strength of 340 N/mm² (shipbuilding quality).
- Toggle bolts and pins: corrosion‑resistant materials, minimum tensile strength 350 N/mm².
- Seal material suitable for marine service with durable sealing/resealing properties.
- Manufacture & finish: Components must be free from distortion and sharp edges; blast cleaning and priming are required to inhibit corrosion.
- Weathertightness testing: Completed hatch assembly installed on board must pass a hose test or equivalent to the satisfaction of the regulatory representative.
- Designation: Example - "Hatch ISO 5778 - 830 × 630".
Applications and users
ISO 5778 is directly useful for:
- Shipbuilders and shipyards specifying or manufacturing small weathertight steel hatches.
- Naval architects and marine designers detailing hatchways, coamings and cover fittings.
- Hatch manufacturers and suppliers seeking interchangeable, standardized hatch designs.
- Classification societies, flag state inspectors and regulatory authorities for conformity checks and weathertightness tests.
- Maintenance and repair yards specifying replacement hatches or retrofits.
Note: These hatches are not suitable for tank access or escape hatches.
Related standards
- ISO 262 - general-purpose metric screw threads (referenced for toggle bolt and wing nut threads).
- International Convention on Load Lines 1966 (LLC66) - referenced for load line and stiffening requirements.
Keywords: ISO 5778:1998, small weathertight steel hatches, shipbuilding, hatch dimensions, coaming, hatch seal, weathertightness testing, LLC66, marine technology.