An API task group has developed the process for assessment of existing platforms to determine fitness for purpose; this has been released as a draft supplement to API RP 2A. The process is prescriptive, with criteria based upon consequence of failure in terms of life safety and environmental impact. Platforms are assessed according to either design basis check or analysis. Two levels of analysis may be used, with increasing complexity and decreasing conservatism design level and ultimate strength. Design level analysis is similar to that used in new platform design, while ultimate strength analysis attempts to provide an unbiased estimate of platform capacity. This paper describes the draft API assessment process and associated acceptance criteria. The criteria are based on over forty years of successful operations, field experience, and detailed investigation of platform failures and survivals in past hurricanes, notably hurricane Andrew. The draft process is currently being tested through a joint industry project, with over 20 participating operators and contractor. BACKGROUND In 1992, an API task group was established with the objective of developing guidelines for assessment (i.e., demonstrate fitness for purpose) of existing platforms. The impetus for developing assessment guidelines was the evolution of platform design practice over the past forty years, resulting in new platform design standards which are considerably more stringent than those used earlier. Concerns were raised by the Minerals Management Service (MMS) regarding the adequacy of older structures, prompted also by the expiration of initial operating permits and by the occurrence of significant environmental events such as hurricane Juan (1985) and the Loma Prieta earthquake (1989). Hurricane Andrew (1992) provided further justification for establishing assessment guidelines, as well as a large amount of reliable information useful in this regard. An API task group, chaired by Kris Digre of Shell, was directed to develop a supplement to the API document, "Recommended practice for Planning, Designing and Constructing Fixed Offshore Platforms - Working Stress Design" (RP 2A - WSD) 20th edition. The supplement was to provide guidance on assessment of fried offshore platforms located in US waters, addressing metwean, earthquake, and ice loading. The task group effort was divided among seven supporting work groups:assessment process,condition assessment,loading,structural,foundations,operational/mitigation measures, andacceptance criteria. Considerable interaction was required between the groups, particularly in establishing criteria. The task group completed the work within one year and issued a draft supplement prior to the International Workshop on Reassessment and Re-qualification of Offshore Production Structures held in New Orleans in December of 1993 [1]. Discussion of the draft supplement was a principal topic at the workshop, and the recommended prescriptive assessment procedure was widely endorsed [1]. The purpose of this paper is to describe the assessment process developed by the API task group and contained in the draft supplement to RP 2A, to discuss the evolution of this assessment process, and to provide justification for the specified acceptance criteria. Discussion will be restricted to the metocean assessment process and criteria; ice and earthquake loading assessments are addressed in [2].

API Recommended Practices for the design and operation of GoM platforms have evolved in recent years due to the impact of large hurricanes in the Gulf of Mexico. This evolution of the API offshore practice is based primarily on work performed by the API HEAT Committee, interim API guidelines (e.g., API 2INT-EX), results from updated technology, and the ultimate harmonization of API RP 2A and ISO 19902. This paper summarizes the latest version of the proposed API RP 2SIM (Structural Integrity Management) and clarifies the intent and basis for the proposed revisions to previous draft versions of API RP 2SIM. Background API RP 2SIM (RP2SIM) has been the subject of recent papers that clearly explain its overall intent, philosophy, and link to international and existing API practices. In summary, SIM (Structural Integrity Management) is a rational framework for evaluating the integrity of a structure through its entire life cycle. SIM was first incorporated into international practice in the mid-1990s in Draft E of ISO 19902. ISO 19902 was officially published in 2007. RP2SIM incorporates sections of ISO 19902, API RP 2A 21st Ed. (Section 14 and Section 17) and API 2INT-EX as a basis with a significant expansion in explanation and clarification. RP 2SIM has been organized around the framework of the overall SIM process consisting of Data, Evaluation, Strategy and Program. The main sections of the document are as follows:–Section 1: Introduction, Purpose and Scope–Section 2: Normative References–Section 3: Definitions and Acronyms–Section 4: Structural Integrity Management Process–Section 5: Surveys–Section 6: Damage Evaluation–Section 7: Structural Assessment Process–Section 8: Assessment Criteria and Loads - API 20th Edition and Earlier Platforms–Section 9: Assessment Criteria and Loads - API 21st Edition and Later Platforms–Section 10: Mitigation and/or Risk Reduction–Section 11: Decommissioning The reader is referred to O'Connor et al. (2005) and Puskar et al. (2006) for further details on each of these sections. RP2SIM will replace the portion of API Bulletin 2INT-EX related to fixed platforms. The original intent of 2INT-EX was an " interim?? guidance document based upon results of the HEAT studies that indicated an assessment was recommended for fixed high consequence L-1 and A-1 structures and floating structures located in the Central Region of the GoM. The Central Region is the location of the largest increase in the estimated extreme hurricane conditions. The " interim?? notation for the EX Bulletin designates that it will be ultimately replaced by other API documents, in this case RP2SIM for fixed platforms. 2INT-EX will be fully replaced once the associated floating structure API documents have been updated to account for assessment, with this work currently underway within API.

An API task group has developed a process for the assessment of existing platforms to determine their fitness for purpose. This has been released as a draft supplement to API RP 2A-WSD, 20 th edition'. Details and the background of this work are described in a companion paper 2 •

This paper provides insights and interpretations regarding the use of API RP2A-WSD 22nd Edition. In 2010, OTC paper #20837 discussed modifications beingmade to and reasons behind the changes to API 2A-WSD in conjunction with othernew API standards, 2MET, 2EQ, 2SIM and 2GEO and the elimination of APIBulletins 2INT-MET, 2INT-DG and 2INT-EX. In this paper, emphasis is placed onuse of the 22nd Edition in combination with the other new standards. General API RP 2A-WSD 22nd Edition was balloted in 2011 and approved by 96% of thevotes cast. There were over 339 individual comments (the vast majorityeditorial) with some 21 still in final resolution by API TG13 at the time thispaper was written. This has resulted in the API RP 2A-WSD 22nd Edition finaltable of contents to include the following (with reference to the 21st EditionSection in parentheses):Section 1: ScopeSection 2: Normative ReferencesSection 3: Terms, Definitions and AcronymsSection 4: Planning (21st Edition Section 1)Section 5: Design Criteria and Procedures (21st Edition Section 2)Section 6: Structural Steel Design (21st Edition Section 3)Section 7: Strength of Tubular Joints (21st Edition Section 4)Section 8: Fatigue (21st Edition Section 5)Section 9: Foundation Design (21st Edition Section 6)Section 10: Other Structural Components and Systems (21st Edition Section7)Section 11: Material (21st Edition Section 8)Section 12: Drawings and Specifications (21st Edition Section 9)Section 13: Welding (21st Edition Section 10)Section 14: Fabrication (21st Edition Section 11)Section 15: Installation (21st Edition Section 12)Section 16: Inspection (21st Edition Section 13)Section 17: Accidental Loading (21st Edition Section 18)Section 18: Reuse (21st Edition Section 15)Section 19: Minimum and Special Structures (21st Edition Section 16)Annex A (Informative): API 2A-WSD 21st Edition vs. 22nd EditionCross-referenceAnnex B (Informative): CommentaryBibliography Changes from OTC paper #20837 and specific topics of importance in using thenew API Standards are discussed below.

The four muclmats wh@h supported the 1353 ft. water depth BullwinMe jacket prior to corner pile installation are unique in size and capability. They were built with 5 ft. deep skirts thus enabling them to: 1) better resist lateral forces, 2) mobilize a greater bearing capacity, 3) provide for an uplift, i.e., suction capacity, and 4) set down "on an uneven seabed. Finally, by injecting nitrogen under the mats they could be used as elevating devices to level the jacket. The design considerations for fabrication, launch, seastate loading, soil behavior, platform dyn"amics and recovery from soil/mudmat failure are presented.