Welding repairs that involve removal and replacement of large sections of piping systems.
Source: API 570, Piping Inspection Code: In-service Inspection, Rating, Repair, and Alteration of Piping Systems, Fourth Edition, February 2016, with Addendum May 2017. Global Standards
Major repairs are those which require shut down of normal operations for an extended period of time (does not include routine dry-docking/ maintenance shutdown).
Source: Guidance Notes on Petroleum and Natural Gas (Safety in Offshore Operations) Rules, 2008, Oil Industry Safety Directorate (India), 2012. Regulatory Guidance