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ENHANCEMENT OF INSPECTION AND MAINTENANCE OF INDUSTRIAL STRUCTURES USING RELIABILITY BASED METHODS AND EXPERT SYSTEMS

Objective

Some indus tries have developed probabilistic methods and tools to estimate a structure's lifetime. Yet these studies which can usually be used at the design stage do not correctly take into account the effect of time (new information, degradation, ...). Up to now no studies have been made to take this information into account, although it is believed that they could lead to an optimization of the inspection and maintenance strategies on any industrial unique structure. Such studies would be most useful in industries involving large multi-element structure, and most evidently in the offshore, nuclear and petrochemical fields where inspection can represent a large percentage of the operating costs, while not always resulting in significant risk reduction costs. The main object is to optimize inspection and maintenance schemes for complex structures by developing probability computation methods and reliability studies for existing structures as well as for future works, and to use the existing methods in order to develop the capability of updating the probability of failure during the life of the structure while taking explicitly into account new information and optimizing the inspection strategy.
A database used for the reliability calculation and for the knowledge based system (KBS) was assembled. An original method, capable of handling time variant reliability problems, was then implemented numerically, and on optimisation module taking into account new information and data on inspection costs was created. It yields an inspection plan for a given element. The method and numerical tool was successfully tested and RAMINO was designed.
RAMINO provides a rational frame for the collected data and the numerical methods developed, complemented with the knowledge obtained from elicitations of field experts and from the collection of non numerical data.
Since the end of the project, partial results were used to develop IMREL (Inspection and Maintenance using Reliability) which was merged with the DGXVII THERMIE project RISC (Reliability Based Inspection Scheduling for fixed offshore platforms). These softwares are marketed by TSC in the United Kingdom and RCP in Muenich.

New ferritic alloys have been developed on an industrial scale (100 kg) with greater erosive wear and corrosion resistance than previously available materials. Towards this goal, high aluminium (24-24% by weight) content iron aluminide intermetallic alloys were produced, tested and manufactured into various products.

Optimum compositions and processing techniques have been specified for the production of environmentally resistant iron aluminide alloys for elevated temperature applications.
Various transformation techniques have been established for the production of standard products from such materials.
A preliminary materials database has been established, showing the materials to have high strength and toughness with excellent corrosion and erosion resistance at elevated temperatures.
Use of ion aluminide alloys as protective coatings has significantly enhanced the mechanical properties of both 316L stainless steel and inconel 600 nickel based superalloys at elevated temperatures by improving the resistance to environmental attack.
Oxide dispersion strengthening of iron aluminide by mechanical alloying has resulted in the production of a creep resistant material with high environmental resistance.

Iron aluminide alloys are being field tested as intake valves in automotive applications. In addition, iron aluminide coatings will be developed for the protection of environmentally sensitive components in elevated temperature applications.

Coordinator

GERTH
Address
Avenue Larribau Cstjf
64018 Pau
France

Participants (6)

COMPUTATIONAL SAFETY AND RELIABILITY
Denmark
O.C. COMSULTING ENGINEERS AND PLANNERS A/S
Denmark
SIEMENS AG
Germany
SOCIETE FRAMATOME
France
Address
Tour Framatome
92084 Paris La Defense
Synthesis Srl
Italy
TECHNISCHE UNIVERSITÄT MUNCHEN
Germany
Address

München