Overview
CEN ISO/TR 19905-2:2013 (ISO/TR 19905-2:2012) is a Technical Report that provides commentary, background and worked examples to support ISO 19905-1 - the site-specific assessment standard for independent leg jack-up units used in the petroleum and natural gas industries. It is informative in nature and includes detailed sample “go-by” calculations plus alternative or additional calculation methods (for example the SIPM drag–inertia method) to help engineers apply the normative requirements in practice.
Key topics and technical content
This TR expands on many technical areas referenced in ISO 19905-1 without replacing them. Major topics include:
- Metocean data guidance (waves, currents, wind, water depths) - interpretation and use for site-specific assessments.
- Hydrodynamic modelling for legs, spudcans and submerged components:
- “Detailed” vs “equivalent” leg models, including guidance on drag and inertia coefficients.
- Effects of shielding, solidification and member length.
- Wave, current and wind load actions and how to represent them in structural and dynamic analyses.
- Soil–structure interaction including spudcan behaviour, limiting horizontal reactions and geotechnical considerations.
- Dynamic properties and response:
- Derivation of effective stiffness (K) and methods for natural period estimation.
- Damping (hysteretic and radiation), P‑Δ (negative stiffness) effects and simplified correction terms.
- Guidance on the drag–inertia method for estimating extreme dynamic response.
- Strength, interaction checks and limit states - background for interaction equations and nominal bending strength checks.
- Informative annexes: a detailed worked example calculation (Annex A), SIPM drag–inertia method (Annex B) and supporting appendices and bibliography.
Practical applications and users
This Technical Report is intended for professionals involved in site-specific assessment, design review and certification of jack-up units:
- Offshore structural and geotechnical engineers
- Naval architects and hydrodynamic specialists
- Asset owners/operators and project engineers planning jack-up deployment
- Classification societies, certifying bodies and regulators performing assessments
- Safety and risk engineers needing defensible, documented calculation approaches
Use ISO/TR 19905-2 to clarify modelling choices, validate input metocean data, implement recommended dynamic analysis methods, and follow a step‑by‑step worked calculation when applying ISO 19905-1 requirements.
Related standards
Keywords: jack-up, site-specific assessment, ISO/TR 19905-2, ISO 19905-1, metocean, hydrodynamic model, spudcan, drag-inertia, offshore structures.