ISO 19905-1:2023

Overview

ISO 19905-1:2023 - Oil and gas industries including lower carbon energy - Site-specific assessment of mobile offshore units - Part 1: Jack-ups: elevated at a site provides requirements, recommendations and guidance for the site-specific elevated assessment (SSA‑E) of independent leg jack‑up units when elevated at a specific site. The standard applies to occupied non‑evacuated, occupied evacuated and unoccupied jack‑ups in petroleum and natural‑gas (and lower‑carbon energy) operations and requires that the as‑installed condition matches the assessment assumptions. It does not cover installation/removal (SSA‑I), transit, design, or well conductor integrity.

Key technical topics and requirements

• Scope and applicability
  • Targets independent leg mobile jack‑ups that are structurally sound and adequately maintained (typically demonstrated by a recognized classification society certificate).
  • Jack‑ups without valid classification are assessed under ISO 19902, with applicable methodologies from ISO 19905‑1.
• Data collection
  • Systematic assembly of jack‑up data, site/operational data, metocean, geophysical/geotechnical, earthquake and ice data.
• Actions and load cases
  • Treatment of metocean actions (waves, currents, wind), functional loads, displacement‑dependent and dynamic effects, earthquakes and ice actions (where applicable).
• Structural modelling
  • Modular modelling approach covering legs, hull, leg‑to‑hull connections, spudcan and foundation, mass modelling and levels of finite‑element (FE) representation.
• Foundations and geotechnical analysis
  • Assessment of foundation behaviour: spudcan reaction, leg penetration, yield interaction, foundation stiffness, vertical‑horizontal capacity envelopes and acceptance checks.
• Assessment methodology
  • Integrated approach - provisions are intended to be used in their entirety to ensure acceptable reliability.
• Special conditions
  • For ice regions, assessors should supplement ISO 19905‑1 with ISO 19906 (ice actions) and ISO 35104 (ice management procedures).
• Exclusions & notes
  • Well conductor integrity, installation/removal procedures and design standards are outside the scope.

Practical applications - who uses this standard

• Offshore operators and asset owners conducting site acceptance and relocation risk analyses.
• Structural, offshore and geotechnical engineers performing SSA‑E modeling, FE analysis and foundation checks.
• Classification societies, regulators and project managers validating compliance and permitting elevated jack‑up operations.
• Consultants and risk assessors preparing site‑specific reports for operations planning, life‑extension studies and safety cases.

Related standards (for implementation)

• ISO 19902 - Assessment of offshore structures (used when classification is absent).
• ISO 19906 - Arctic offshore structures / ice actions (supplement for ice regions).
• ISO 35104 - Ice management procedures.
• IMO MODU Code and recognized class rules - design and operational guidance references.

Keywords: ISO 19905-1:2023, SSA-E, jack-ups, site-specific assessment, mobile offshore units, metocean, structural modelling, spudcan, geotechnical analysis, classification society.