Vulnerability of welded joints and active damage mechanisms in petrochemical plants and processes: reliability through programming of risk based inspection (RBI) – Part II

Abstract

The special process of welding still plays a key role in the fabrication of pressurised 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 (RBI) method, with the aim of prioritising and optimising the inspection strategy, focusses attention on the criticality of welded joints with the framework of problems related to both simple mechanical vulnerability and physico-chemical 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 optimising 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

Italian translation of the paper presented at EUROJOIN 7 – GNS5 Technical Session: “Reliability of welded components and structures” Venice Lido. 21-22 May 2009.

Additional information

Notes on contributors

G. Canale

Giancarlo Canale obtained his degree in mechanical engineering from the Faculty of Engineering, University of Genoa in 1986, and entered the Italian Welding Institute in 1987, becoming involved in training and technical support in the field of the construction and operation of pressure tanks and piping, operating in the refinery and energy production sectors. In 1995 he was appointed as director with responsibility for management of the Sicily branch of the IWI. In 2000 he became central Manager for the IWI branches and commercial manager. In 2005 he became director of the engineering division of the IWI. He is currently technical Director at IIS Service. He is certified as a European/International Welding Engineer and Level 3 EN 473.

M. De Marco

Marco De Marco obtained his degree in Chemical Engineering from the University of Genoa in 2000. He has been an official of the Italian welding Institute since 2002 and has been mainly involved in activities relating to the problems of monitoring and interpretation of corrosion phenomena, weldability, material selection, failure analysis; he has also participated in the planning and execution of process plant inspection activities. He is a certified European/International Welding Engineer (IWE). NACE corrosion Technologist and NACE Coating Inspector Level I. He has participated in several NACE working parties for the revision of documents relating to corrosion monitoring and control.

S. Pirica

Stefano Pinca obtained his degree in Mechanical Engineering from the University of Genoa in 1994. He has been an Official of the Italian Welding Institute since 1995, and is currently manager of the Engineering sector at IIS Service, where he is involved in consultancy for calculations in relation to welded structures and components, evaluation of reliability and planning Risk based Inspection programs. He is a Certified European/International Welding Engineer and Level 2 PT-MT-RX EN 473.