Abstract

Encouraged by the industry, Det Norske Veritas (DNV) has taken the initiative to initiate a Joint Industry Project (JIP) that addresses issues that are not sufficiently covered by the current ISO standard for subsea umbilicals, ISO 13628-5. The main objective of this JIP is to develop a proposed draft for revision of ISO 13628-5. The JIP was started in May 2004, and the work is coordinated with on-going activities in the American Petroleum Institute (API).

The scope of work includes several topics ranging from general aspects such as establishment of a safety philosophy to detailed technical analysis of steel tube design. In the technical work emphasis is put on global analyses, fatigue and cross-section analysis, but specific issues related to testing, electrical components, metallic tubes and installation will also be addressed.

Introduction

The industry has identified several topics that are not sufficiently covered by the current international standard for subsea umbilicals, ISO 13628-5. This ISO standard is based on API Spec 17E, second edition, September 1998, and API RP 17I, first edition, August 1996. DNV has performed technical analyses and processed information from the participants covering the topics that need to be treated more extensively in the ISO standard. The activities have been coordinated with API in order to keep the ISO and API documents synchronized. The results from the JIP will be published as proposed text for a revised ISO 13628-5 in May 2005. This will then be followed by a formal ISO ballot procedure before the proposed text can be published as a new standard. This paper describes the proposed changes and the technical justifications for these proposals. All proposed changes to the standard will be based on experience among the JIP-participants.

Proposed changes to the ISO 13628-5 standard

The following tasks have been defined in the JIP.

General aspects

These aspects are proposed to be included in chapter 5 of the standard. Further, other relevant paragraphs of the ISO document have to be reviewed and the safety principles have to be implemented.

Safety philosophy

The principles and requirements stated in the current DNV Offshore Standard for dynamic risers (DNV OS-F201) /1/ has been adopted and modified to fit subsea umbilicals.

Reliability philosophy

Guidance with respect to the scope of reliability analyses is defined, and references to documents that state the general principles of such analyses are given. The focus of such analyses should be on the total system, including electrical systems.

Qualification and testing philosophy

The principles and requirements of the DNV Recommended Practice for qualification of new technology (DNV RP-A203) /2/ has been adopted and made specific for subsea umbilicals. Specific testing procedures and the use of cross-section analyses are also addressed.

List and distribution of typical engineering tasks

A table showing the typical distribution of work and preferred roles for the different companies, i.e. purchaser, contractor and manufacturer, will be included.

Design
Global analysis

It is proposed to maintain the overall structure of section 6 of the current ISO document.

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