Vulnerability of welded joints and active damage mechanisms in petrochemical plants and processes: reliability through programming of risk-based inspection – Part I

Abstract

The special process of welding still plays a key role in the fabrication of pressurized equipment for the energy processing and generation industry. Similarly, welding is extensively used in repair, modification and overlay/cladding procedures and during the maintenance operations for large plants. However, the harsh statistics relating to faults shows welded joints to be among the most ‘at-risk’ areas with regard to various active damage mechanisms. Within the framework of the management of plant risk and equipment integrity, the risk-based inspection method, with the aim of prioritizing and optimizing the inspection strategy, focuses attention on the criticality of welded joints with the framework of problems related to both simple mechanical vulnerability and physicochemical aspects such as corrosion and/or stress corrosion. The aim of this paper is to offer an overview of the interactions existing between the various active damage mechanisms in plants and welded joints in addition to indicating the criticality associated with these interactions, with the purpose of optimizing the management of plant risk and inspection strategies for resolving them.

Keywords:

• chemical engineering
• corrosion
• creep resisting materials
• elevated temperature strength
• failure
• fracture mechanics
• high pressure
• in service operations
• lifetime
• mechanical properties
• optimisation
• plants
• pressure vessels
• repair
• reviews
• risk-based inspection
• safety factors
• statistical methods
• stress corrosion
• welded joints

Notes

^‡Paper presented at EUROJOIN 7 – GNS5 Technical Session: ‘Reliability of welded components and structures’ Venice Lido, 21–22 May 2009.