Structural integrity

Overview

Guidance is provided below to assist duty holders to comply with the structural integrity requirements of the UK regulations for offshore installations with particular reference to the Offshore Installations (Offshore Safety Directive) (Safety Case etc.) Regulations 2015 (SCR2015) (SI 2015/398) and the Offshore Installations and Wells (Design and Construction etc.) Regulations (DCR) (SI 1996/913).

Structural integrity is fundamental to the safety of the workforce.  It is assured by inherently safe design based on good practice and must be maintained throughout the installation lifecycle by an appropriate management system of inspection, analysis and repair.

Structural failure could cause the immediate total loss of an installation, with little chance of survival.  Failure could arise through:

  • Overloading and / or inherent weakness
  • Deterioration due to ageing or from fabrication defects
  • Damage due to accidental or rare events
  • Inappropriate operator actions (eg during jack-up jacking and preloading operations)

HSE's Structural Integrity Management Information Sheet for offshore installations addresses the integrity management of all types of offshore installation, including fixed platforms and mobiles (jack-ups, semi-submersibles, FPSOs), and the threat to structural integrity from major hazards.  The main topic areas are:

  • Structural integrity management:
    • Underwater integrity of fixed installations (including deterioration)
    • Topside structural integrity and fabric maintenance
    • Integrity of floating / mobile installations (hull and deck)
    • Integrity of jack-up legs, spud can and leg / hull connections
  • Major hazard risk management:
    • Extreme weather and metocean conditions
    • Dynamic response (boat impact and seismic)
    • Fire and explosion response (loading; response; acceptance criteria; control measures)
    • Foundation failure

Guidance and standards

The safe operation of offshore installations is reliant on the availability of appropriate guidance and standards. HSE has been committed to influencing the development of ISO standards from the outset to ensure that they are directly relevant to the UK offshore environment and that the standards provide adequate structural integrity provisions in support of the UK's offshore legislative safety regime.

HSE Guidance

The tables below set out the information available on our website.

Offshore Information Sheets

Offshore information sheets provide good practice guidance on a range of technical issues. For Structural Integrity, the relevant offshore information sheets are noted below:

Fixed Installation Extreme Weather Project

HSE are reviewing the effects of extreme weather on fixed offshore installations. A project was commissioned to assess current knowledge of extreme metocean conditions and associated loadings. This was then compared to current codes of practice. The Extreme Environmental Loading Study page provides further details on:

  • Current project status
  • Overview of the next steps in this project
  • Links to the project research reports which have been completed.

Inspection Guide

The Structural Integrity Inspection Guide outlines an approach to the inspection of duty holder's arrangements with respect to Structural Integrity Management (SIM), and the key areas that inspectors should consider when inspecting this topic. It also sets out the criteria for satisfactory and unsatisfactory performance factors against which duty holder performance will be rated.

Other

Additional general guidance can be found in the following documents. They provide general information relating to how inspectors will assess the acceptability of safety cases as well as the basis for successful health and safety management.

Standards

The offshore regulatory regime is underpinned by standards which define industry good practice. Various structural integrity standards are used in the design and operation of offshore installations, produced and published by API, NORSOK, DNV, BSI and ISO. The ISO 19900 series of standards for the design and reassessment of offshore installations provides detailed guidance on the design and operation of offshore installations and has been developed over a period of time with a view to harmonising industry practice internationally. HSE’s structural inspectors have played an active role in the development of ISO standards for offshore structures. However, the use of other standards is historical. When other standards are used in place of ISO, it is expected that duty holders will consider where the selected standard may not meet the requirements of the relevant ISO standard and address the matter in any reassessment of the structural integrity.

Research and Development

HSE has funded a substantial body of research focused on challenging issues which face the industry. The findings are published in research reports. Completed research reports in structural integrity can be divided into six key technical areas (TA1-TA6) with miscellaneous projects in TA7. 

  • TA1 - Structural integrity management of offshore installations (floating, fixed and jack-up installations; topsides and substructure), including ageing and life extension considerations
  • TA2 - Dynamic loading (including seismic and boat impact) and response
  • TA3 - Foundation failure (including jack-up site investigation)
  • TA4 - Materials technology (such as high strength steels, ship steels, concrete, cold climate effects etc.)
  • TA5 - Uncertainties in extreme weather hazards
  • TA6 - Fire and explosion response
  • TA7 - Miscellaneous
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Updated 2023-04-25