This presentation will describe pipeline isolation tooling and techniques that enable safe repair or modification of pressurised pipelines. Double block and bleed pipeline isolation methods will be explained for piggable and unpiggable pipeline systems. Examples will be presented highlighting the benefits of double block and bleed pipeline isolation and how they are applicable to scenarios such as: • Emergency pipeline repair • Retrospective installation of pigging facilities – making unpiggable pipelines piggable • Removal and replacement of a pipeline section, or a deadleg • Installation, repair or replacement of pipeline valves (Subsea Isolation Valves, Emergency Shutdown Valves, PLR isolation Valves) • Pipeline infrastructure development - new pipeline tie-ins into existing pipelines • Decommissioning, disconnection or retirement of pipeline sections or deadlegs Concluding with recent case studies where double block and bleed isolation has facilitated repair or modification of Major Subsea Pipelines in the North Sea. In one case 40% of UK oil production was dependent on a successful isolation.