Background to the ISO 19905-Series and an Overview of the New ISO 19905-1 for the Site-Specific Assessment of Mobile Jack-Up Units
Authors: Hoyle Mike , Stiff John James , Hunt Rupert J. 
Published: April 2012

This keynote paper describes the place, significance and development of the ISO19905-series standards (Mobile Offshore Units) within the 19900-series ofoffshore structures standards. It provides an overview of both the new standardfor the site-specific assessment of jack-ups, ISO 19905-1 [ref. 1], and thesupporting technical report, ISO/TR 19905-2 [ref. 2]. The Technical Reportcontains background information and a detailed example "go-by" calculation, afeature previously found to be extremely useful. The paper is one of seven in aseries outlining the key technical aspects of the development of ISO 19905-1and their significance in relation to the SNAME T&RB 5-5A source document[ref. 3]. The planned ISO 19905 3, site-specific assessment of floating units, will be described, but not discussed in any detail.

In 1996, ISO Work Group 7, part of Sub-Committee 7, was formed and mandated bythe parent ISO Technical Committee, ISO/TC67, to develop the jack-up siteassessment standard using SNAME T&RB 5-5A as the basis. While thedevelopment of 5-5A, first published in 1994, was rigorous, conscientious, andbased on state of the art knowledge, the published document contained much thatwas new, controversial and perceived by some to be too conservative. Consequently the IADC and others sponsored many projects to advance the processand accuracy of site assessment. Some of this work was incorporated intorevisions of 5-5A, but after 19905-1 started to be developed, much was takendirectly into that document, bypassing 5-5A. This paper provides an overview ofthe projects undertaken and the process used to develop ISOs 19905-1 and19905-2. Other papers in the session give the detailed background to thechanges from 5-5A.

The approach chosen in ISO 19905-1, although sometimes different from that inSNAME and other relevant ISO 19900 series standards, has been developed toembrace new technology whilst providing a site assessment methodology forjack-ups that is robust, calibrated against the best-practice application of5-5A, and allowing for improved technology/computing capability.

The Jack-Up site-assessment ISO will be increasingly used throughout the worldand it is vital that potential users are confident that the standard has asound provenance.

Introduction

This paper is the first of a series of complementary papers describingtechnical aspects of the development of ISO 19905-1 in relation to the SNAMET&RB 5-5A source document. The other papers are:23342: Dowdy et al., " Environmental Actions in the New ISO for theSite-Specific Assessment of Mobile Jack-Up Units", 23040: Tan et al., " Structural Modelling and Response Analysis in the New ISOStandard for the Site-Specific Assessment of Mobile Jack-Up Units"23521: Wong et al., " Foundation Modelling and Assessment in the New ISOStandard for the Site-Specific Assessment of Mobile Jack-Up Units"23071: Frieze et al., " Structural Acceptance Criteria in the New ISO Standardfor the Site- Specific Assessment of Mobile Jack-Up Units"23337: Kudsk et al., " Long-Term Applications in the New ISO Standard for theSite-Specific Assessment of Mobile Jack-Up Units"22949: Stiff et al., " Benchmarking of the New ISO Standard for theSite-Specific Assessment of Mobile Jack-Up Units"