NDTnet 1998 Aug, Vol.3 No.8

Full-Text - Abstract

A riser forms the connection between the top side of an offshore platform and a pipeline on the sea-bed. Such pipeline systems may be equipped with launch and receive facilities for cleaning and general intelligent pigging of the entire pipeline. In this paper a new approach for a detailed ultrasonic inspection of the risers only is explained, based on the application of umbilical operated tools with on-line presentation of results.

For risers, which are usually encased or not accessible from the outside, alternative to intelligent pigging, inspection from the outside is impractical and often impossible. In this case, cable operated inspection from the inside is more practical and can provide full coverage over the entire height. Single side access from the platform must be arranged to utilize such cable operated tools. This requires shutting down, Repressurization, opening of riser and filling the riser with a liquid, unless it is an oil riser.

Apart from power supply and hoisting equipment no other facilities are needed. The umbilical allows full control over the tool speed and performance and above all on-line presentation of the inspection results. These are very attractive features for pipeline owners as this decreases the risks.

This paper also describes the rationale behind an Alskan platform and pipeline operator (UNOCAL) for the selection of and experience with RTD cable tools.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

Publication Contact:
7th ECNDT, Park Alle 345, DK-2605 Broendby, Denmark, Fax: +45 46 26 70 11, Email: 101373.3414@compuserve.com