How to Age Gracefully – Pipeline Life Extension. SPE 182262 By Allison Selman, Atteris Pty Ltd Rex Hubbard, Atteris Pty Ltd, 13 Oct 2016

This paper presents the engineering process for performing a design life extension study (or design requalification) for an offshore pipeline system. The principles and process however, could be applied to design requalification of any physical asset.

Every pipeline system is designed for a theoretical maximum duration called its design life. In some instances there may be a requirement to continue operations beyond this date. This paper provides guidance on the technical life extension processes and procedures and it focusses on the engineering that is required to provide adequate assurance for safe continued operations.

This paper presents the two main international guidelines that are typically used: NORSOK Y-002 and ISO 12747. The life extension process will be discussed step-by-step with guidance on technical considerations at each stage.

A case study example is used to demonstrate how the process has been applied to assess the fitness for service of an offshore pipeline system for an additional 10 years. The case study describes some of the key engineering assessments which may be required to support the life extension assessment and includes an example of a probabilistic corrosion assessment that enabled deferral of a high cost subsea-to-shore inspection pigging campaign.

Pipeline life extension opens up many development opportunities, especially in challenging economic conditions. If a pipeline can be re-used or re-purposed for future developments then significant CAPEX reductions can be achieved for small, nearby developments. To enable this opportunity the risks of continued operation must be fully understood following a systematic and comprehensive approach to assess the risks. Once the risks are understood then they can be adequately managed through a proactive integrity management program.