ISO 8314:1987

Overview

ISO 8314:1987 is an International Organization for Standardization (ISO) standard that specifies dimensions and materials for trunnion pieces used in span bearings and lead block bearings on ship derrick booms. It defines geometry, nominal sizing, material grades, tolerances and basic assembly guidance for trunnion pieces and locating bolts used in cargo handling and lifting gear on ships.

Key topics and technical requirements

• Three trunnion types:
  • Type A - single lower eye
  • Type B - centrally‑located eye
  • Type C - two eyes (one upper, one lower)
• Nominal size: a numerical designation derived from the permissible load at the eyes (expressed in kilonewtons) for ordering and reference.
• Materials:
  • Trunnion piece: minimum material grade Fe 360 (steel) per ISO 630
  • Bolt/pin: minimum material grade Fe 430 per ISO 630
  • Option for higher quality: heat‑treated quenched steels compliant with ISO 683/1 when required
• Dimensions and tolerances:
  • Main dimensions are given in millimetres in figures and tables of the standard (Figures 1–3, Tables 1–2)
  • Certain eye and fork dimension values align with ISO 6043
  • Dimensional tolerances correspond to tolerance grade ST 34 per ISO 286/1
• Assembly guidance:
  • Illustrative assembly examples are provided (not prescriptive for bracket construction)
  • Bolts/pins must be secured by a suitable device; washer use is optional and may be positioned above or below the trunnion depending on derrick lashing
  • Bolt shape and length should suit the design of the bearing bracket

Applications and who uses the standard

ISO 8314 is directly applicable to professionals involved in shipboard cargo handling and lifting equipment:

• Shipbuilders and shipyards specifying and manufacturing derrick boom components
• Naval architects and structural designers detailing span bearings and lead block bearings
• Classification societies and surveyors reviewing compliance for safety and design acceptance
• Equipment manufacturers, procurement teams and quality inspectors ensuring material and dimensional conformity
• Maintenance engineers and refit yards replacing or ordering trunnion pieces and pins

Related standards

Key related ISO documents referenced by ISO 8314 include:

• ISO 630 - Structural steels
• ISO 683/1 - Heat‑treatable steels (for higher quality requirements)
• ISO 286/1 - ISO system of limits and fits (tolerances)
• ISO 6043 - Eye and fork assemblies under tension load (main dimensions)
• ISO 8147 - Shipbuilding and marine structures - derrick rigs and components (vocabulary and related definitions)

ISO 8314 helps ensure consistent, safe, and interchangeable trunnion components for shipboard lifting gear by standardizing dimensions, materials and basic assembly practices.