DNV—GL — PIPELINE SUBSEA REPAIR

Another recommended practice prepared and released by DNV GL classification society. The opening section of the document provides general introductory information about pipeline IMS, i.e. integrity management system, application of the document, and pipeline failure causes, statistics and repair systems. The second section is dealing with the basic safety philosophy - the content of this section also covers systematic review, qualification and limit state design.

The next three sections cover the pipeline repair activities, design basis and exposures. The fourth section is devoted to the fitting design including failure causes and modes, fitting strength and grip capacity, seal capacity and other aspects. The remaining sections of the publication are dealing with the installation of the pipelines and attachment to them, seal protection design, limitations imposed at the misalignment, control and monitoring, activation etc., isolation plugs including testing of the associated isolation tools, hot tapping covering structural integrity and failure modes, welding and testing considerations, quality assurance, documentation etc.

The appendices provide additional information about the design factors and code breaks, typical tests and fitting capacity, failure statistics and risk assessment, checklist for qualification, design resistance etc.