ISO/TC 67/SC 7/WG 7 - Site specific assessment of mobile offshore units (MOUS)

This document specifies requirements and provides recommendation and guidance for the elevated site-specific assessment (SSA-E) of independent leg jack‑up units for use in the petroleum and natural gas industries. It addresses: a) occupied non-evacuated, occupied evacuated and unoccupied jack‑ups; b) the installed (or elevated) phase at a specific site. It also addresses the requirement that the as-installed condition matches the assumptions used in the assessment. This document does not address the site-specific assessment of installation and removal (SSA-I). To ensure acceptable reliability, the provisions of this document form an integrated approach, which is used in its entirety for the site-specific assessment of a jack‑up. When assessing a jack-up operating in regions subject to sea ice and icebergs, it is intended that the assessor supplements the provisions of this document with the relevant provisions relating to ice actions contained in ISO 19906 and procedures for ice management contained in ISO 35104. This document does not address design, transit to and from site, or installation and removal from site. This document is applicable only to independent leg mobile jack-up units that are structurally sound and adequately maintained, which is normally demonstrated through holding a valid recognized classification society, classification certificate. Jack‑ups that do not hold a valid recognized classification society certificate are assessed according to the provisions of ISO 19902, supplemented by methodologies from this document, where applicable. NOTE 1 Well conductors can be a safety-critical element for jack‑up operations. However, the integrity of well conductors is not part of the site-specific assessment process for jack‑ups and is, therefore, not addressed in this document. See A.1 for guidance on this topic. NOTE 2 RCS rules and the IMO MODU code (International Maritime Organisation Mobile Offshore Drilling Unit code) provide guidance for the design of jack-ups.

This document specifies requirements and recommendations for the site-specific assessment of mobile floating units for use in the petroleum and natural gas industries. It addresses the installed phase, at a specific site, of manned non-evacuated, manned evacuated and unmanned mobile floating units. This document addresses mobile floating units that are monohull (e.g. ship-shaped vessels or barges); column-stabilized, commonly referred to as semi-submersibles; or other hull forms (e.g. cylindrical/conical shaped). It is not applicable to tension leg platforms. Stationkeeping can be provided by a mooring system, a thruster assisted mooring system, or dynamic positioning. The function of the unit can be broad, including drilling, floatel, tender assist, etc. In situations where hydrocarbons are being produced, there can be additional requirements. This document does not address all site considerations, and certain specific locations can require additional assessment. This document is applicable only to mobile floating units that are structurally sound and adequately maintained, which is normally demonstrated through holding a valid RCS classification certificate. This document does not address design, transportation to and from site, or installation and removal from site. This document sets out the requirements for site-specific assessments, but generally relies on other documents to supply the details of how the assessments are to be undertaken. In general: — ISO 19901‑7 is referenced for the assessment of the stationkeeping system; — ISO 19904‑1 is referenced to determine the effects of the metocean actions on the unit; — ISO 19906 is referenced for arctic and cold regions; — the hull structure and air gap are assessed by use of a comparison between the site-specific metocean conditions and its design conditions, as set out in the RCS approved operations manual; — ISO 13624‑1 and ISO/TR 13624‑2[1] are referenced for the assessment of the marine drilling riser of mobile floating drilling units. Equivalent alternative methodologies can be used; — IMCA M 220 is referenced for developing an activity specific operating guidelines. Agreed alternative methodologies can be used. NOTE RCS rules and the IMO MODU code[13] provide guidance for design and general operation of mobile floating units.

ISO/TR 19905-2:2012 provides a commentary to some clauses of ISO 19905-1 including background information, supporting documentation, and additional or alternative calculation methods as applicable and also provides a detailed sample 'go-by' calculation. ISO 19905-1 specifies requirements and guidance for the site-specific assessment of independent leg jack‑up units for use in the petroleum and natural gas industries.

ISO 19905-3 specifies requirements and gives guidance for the site-specific assessment of mobile floating units for use in the petroleum and natural gas industries. It addresses the installed phase, at a specific site, of manned non-evacuated, manned evacuated and unmanned mobile floating units. ISO 19905-3 addresses mobile floating units that are monohull (e.g. ship-shaped vessels or barges); column-stabilized, commonly referred to as semi-submersibles; or other hull forms (e.g. cylindrical/conical shaped). It is not applicable to tension leg platforms. Stationkeeping can be provided by a mooring system, a thruster assisted mooring system, or dynamic positioning. The function of the unit can be broad, including drilling, floatel, tender assist, etc. In situations where hydrocarbons are being produced, there can be additional requirements. The requirements of ISO 19905-3 apply to the hull and stationkeeping system for all types of mobile units. The activity specific operating guideline document requirements can be modified to be appropriate to the situation being assessed. ISO 19905-3 does not address all site considerations, and certain specific locations can require additional assessment. ISO 19905-3 is applicable only to mobile floating units that are structurally sound and adequately maintained, which is normally demonstrated through holding a valid RCS classification certificate. ISO 19905-3 does not address design, transportation to and from site, or installation and removal from site. ISO 19905-3 sets out the requirements for site-specific assessments, but generally relies on other documents to supply the details of how the assessments are to be undertaken. In general: - ISO 19901‑7 is referenced for the assessment of the stationkeeping system; - ISO 19904‑1 is referenced to determine the metocean actions on the unit; - ISO 19906 is referenced for arctic and cold regions; - the hull structure and airgap are assessed by use of a comparison between the site-specific metocean conditions and its design conditions, as set out in the RCS approved operations manual; - ISO 13624‑1 and ISO/TR 13624‑2[1] are referenced for the assessment of the marine drilling riser of mobile floating drilling units. Equivalent alternative methodologies can be used; - IMCA M 220[5] is referenced for developing an activity specific operating guidelines. Agreed alternative methodologies can be used. NOTE 1 The scope of ISO 19904‑1 specifically states that its requirements do not apply to mobile units, but the methodologies given for assessing metocean actions can be used. NOTE 2 RCS rules and the IMO MODU code[4] provide guidance for design and general operation of mobile floating units.

ISO 19905-1:2016 specifies requirements and guidance for the site-specific assessment of independent leg jack‑up units for use in the petroleum and natural gas industries. It addresses: manned non-evacuated, manned evacuated and unmanned jack‑ups; the installed phase at a specific site. To ensure acceptable reliability, the provisions of this part of ISO 19905 form an integrated approach, which is used in its entirety for the site-specific assessment of a jack‑up. This part of ISO 19905 does not apply specifically to mobile offshore drilling units operating in regions subject to sea ice and icebergs. When assessing a jack-up operating in such areas, it is intended that the assessor supplement the provisions of this part of ISO 19905 with the provisions relating to ice actions and procedures for ice management contained in ISO 19906. This part of ISO 19905 does not address design, transportation to and from site, or installation and removal from site. However, it is advisable that the assumptions used in the assessment be checked against the as‑installed configuration. To ensure that the design of the jack‑up is sound and the structure is adequately maintained, this part of ISO 19905 is applicable only to independent leg jack‑ups that either: - hold a valid classification society certification from a recognized classification society (RCS) throughout the duration of the operation at the specific site subject to assessment; or - have been verified by an independent competent body to be structurally fit for purpose for elevated situations and are subject to periodic inspection, both to the standards of an RCS. NOTE 1 An RCS is an International Association of Classification Societies (IACS) member body, meeting the RCS definition given in 3.52. Jack‑ups that do not comply with this requirement are assessed according to the provisions of ISO 19902, supplemented by methodologies from this part of ISO 19905, where applicable. NOTE 2 Future revisions of this part of ISO 19905 can be expanded to cover mat-supported jack‑ups. NOTE 3 Well conductors are a safety-critical element for jack‑up operations. However, the integrity of well conductors is not part of the site-specific assessment process for jack‑ups and is, therefore, not addressed in this part of ISO 19905. Annex A provides references to other publications addressing this topic. Note 4 RCS rules and the IMO MODU code provide guidance for the design of jack-ups.

ISO 19905-1:2012 specifies requirements and guidance for the site-specific assessment of independent leg jack‑up units for use in the petroleum and natural gas industries. It addresses manned non-evacuated, manned evacuated and unmanned jack‑ups; the installed phase at a specific site. To ensure acceptable reliability, the provisions of ISO 19905-1:2012 form an integrated approach, which is used in its entirety for the site-specific assessment of a jack‑up. ISO 19905-1:2012 does not apply specifically to mobile offshore drilling units operating in regions subject to sea ice and icebergs. When assessing a jack-up operating in such areas, it is intended that the assessor supplement the provisions of ISO 19905-1:2012 with the provisions relating to ice actions and procedures for ice management contained in ISO 19906. ISO 19905-1:2012 does not address design, transportation to and from site, or installation and removal from site. However, it is advisable that the assumptions used in the assessment be checked against the as-installed configuration. To ensure that the design of the jack‑up is sound and the structure is adequately maintained, ISO 19905-1:2012 is applicable only to independent leg jack‑ups that either: hold a valid classification society certification from a recognized classification society (RCS) throughout the duration of the operation at the specific site subject to assessment, or have been verified by an independent competent body to be structurally fit for purpose for elevated situations and are subject to periodic inspection, both to the standards of an RCS. Jack‑ups that do not comply with this requirement are assessed according to the provisions of ISO 19902, supplemented by methodologies from ISO 19905-1:2012, where applicable.