Computed radiography deployed by a subsea remotely operated vehicle

Abstract

Arguably, the Remotely Operated Vehicle (ROV) business traditionally understands the word 'Inspection' as a general or close visual record of a subsea item using a remote camera and other data-gathering peripherals such as sonar, bathymetric and profilers. Subsea NDT methods with ROVs are generally confined to cathodic potential surveys, single-point wall thickness measurements and flooded member detection. Conventional NDT is usually diver-deployed in hyperbaric habitats more than in the wet, usually to test for welding defects. In contrast, topsides plant inspection is synonymous with NDT and invariably means components undergo some form of non-destructive examination to provide integrity information. In addition, the last 15 years or so has seen a revolution in NDT systems and inspection companies have gradually introduced 'Advanced' NDT systems to their range of services, to meet the ever-increasing demands from Risk Based Inspection (RBI) approaches to managing pressure systems. The upstream oil and gas industry is now applying the same RBI approach subsea, but with the ever-present HSE restrictions on using divers in addition to deeper water exploration and production, there is a growing requirement for ROV-deployed NDT systems.