Overview
ISO 3904:1990 - Shipbuilding and marine structures - Clear-view screens (rotating portholes) specifies design, construction, designation and installation requirements for rotating clear-view screens used on ships. The standard sets dimensional tolerances, material and mechanical properties, electrical equipment rules and installation criteria to ensure continuous clear vision in harsh marine weather by rotating a glass disk at high speed.
Key topics and technical requirements
- Function: A motor-driven glass disk rotates at high speed to remove spray, rain, hail and snow and prevent fogging, maintaining a clear view.
- Classification: Three types by motor position:
- Type A: Motor eccentric at top of frame
- Type B: Motor eccentric at side of frame
- Type C: Motor mounted at center of the disk
- Rotation speed: Disk rotation must be at least 1600 rpm.
- Clearance (play): Max gap between outer edge of the glass disk and the frame is 2 mm.
- Balance and eccentricity: Disks must be dynamically balanced; axial and radial mass eccentricity limits are specified (see table references in the standard).
- Materials:
- Frame (dormant): Aluminium or copper alloy meeting prescribed mechanical properties.
- Other metal parts: Aluminium alloy, copper alloy or corrosion‑resistant steel.
- Seals: Natural or synthetic rubber, hardness 35–40 DIDC (per ISO 48).
- Glass disk: Tempered safety glass (clear) in accordance with ISO 3254.
- Electrical equipment:
- Cables, switches and control gear must comply with IEC/CEI 92.
- Motors should follow IEC/CEI 34 recommendations; motors are located inside the vessel and need not be fully watertight (IP33 acceptable).
- Anti‑interference (radio suppression) devices are required to prevent electromagnetic disturbance.
- Defrosting provision: Heating/defrosting is not mandatory but designs must allow retrofit of such systems.
- Designation format: Standardized naming (e.g., Hublot tournant ISO 3904 - A - 330 - CU - 34) that includes type, nominal size, frame material code and power supply reference.
Applications and who uses it
ISO 3904 is used by:
- Shipbuilders and naval architects specifying wheelhouse windows and portholes
- Marine equipment manufacturers designing clear‑view screens and replacement glass disks
- Classification societies and shipyards for compliance checks and installations
- Ship operators and retrofitting specialists upgrading bridge visibility systems
Typical applications include bridge/window installations, steerage windows and direct bulkhead mountings where continuous clear vision in adverse weather is essential.
Related standards
- ISO 3254 - Tempered safety glass for ship windows
- ISO 48 - Rubber hardness testing (DIDC)
- IEC (CEI) 34 - Rotating electrical machines
- IEC (CEI) 92 - Shipboard electrical installations
Keywords: ISO 3904, clear-view screens, rotating portholes, shipbuilding standard, marine structures, glass disk, installation requirements, marine electrical equipment.
