Objective Steels and weldments mechanical properties- Materials and components feasibility in Europe.- The strength of the materials is mainly dependent on the Tempering Parameter (resulting of the cumulative softening effect of both tempering and PWHT). A maximum value of TP=T (20+logt) will be of 21 000 for V-modified 21/4 and 3Cr1Mo steels.- The creep properties fall in the scatter band of reference curves for all material tested.- The sensitivity to Temper Embrittlement (as evaluated by the Charpy V curve after step cooling) was found to be very low for all six materials tested, in relation with low values of J-factor.- Base materials of the new V-modified 21/4, 3 and 9Cr 1 Mo were successfully manufactured by European steel makers as very thick products.- Filler metals convenient for the welding of V-modified materials were made available in industrial conditions by the two European manufacturers involved in the research and welding and post weld heat treatment recommendations have been proposed.Hydrogen effect (with or without stress):- Autoclave exposure of specimens (without stress applied) performed in the temperature range of 575 to 650°C with time up to 4000 hours permitted to rank the steels in the following order with decreasing susceptibility:a) Standard 21/4 Cr 1 Mo steel (sensitive)b) V-modified 21/4 Cr 1 Mo steels (low sensitvity)c) V-modified 3 Cr 1 Mo steels and V-modified 9 Cr 1 Mo steel (not sensitive).In addition, it was clearly observed that the fine grain area of HAZ presents the highest hydrogen damage for all materials.- Creep tests performed in hydrogen environment showed that:1. creep rupture time and creep ductility of standard material and welds were drastically reduced, out of the code lower limit.2. the susceptibility to hydrogen is in accordance with the results of autoclave tests.Operation at higher temperatures with improved safety- The improvement of both the creep resistance and the resistance to hot hydrogen attack due to V addition is confirmed.- No deterioration of the resistance to temper embrittlement was observed after step-cooling when comparing V-modified steels and standard steel with similar high purity level C.- So, the possibility to operate at higher temperature than the standard material is clearly demonstrated.- For improving safety, a recommendation will be to adapt the in-service inspection programmes on the detection of cracks in the high stresses/high temperature welds of the oldest reactors manufactured with the standard material.Microstructural evaluation and Model sensitivity- Microstructural description of the materials was efficient from TEM/EDS by using the carbide extraction replicas technique. However, due to the non-homogeneous distribution of carbides, it was very difficult to obtain quantitative and representative results on percentage of different carbides and carbides spacing.- The nature and size of carbides were found to be modified by the exposure to temperature and hydrogen. Their chemical composition directly affects the equilibrium of methane pressure in the base materials: the model confirms the ranking of steels after autoclave tests.- After fitting the creep data to experiments in air, the creep behaviour in hydrogen of the standard and V-mod 21/4Cr 1 Mo steels was correctly predicted by the model.- FE calculations of a weld subjected to hydrogen pressure at high temperature showed that the rupture time is highly sensitive to the spacing of cavities. Unfortunately, this data is difficult to obtain.- The sophisticated model developed in this work can successfully describe the hydrogen/creep damage. However, its practical use is probably limited due to the rather large amount of input data, which are necessary to describe the material microstructure.Objectives and content High temperature, high pressure reactors are the more critical components of hydroprocessing units. The standard material for these vessels, 2.25Cr-lMo steel, has temperature limitations (max. 450øC) due to creep and hydrogen attack. In the near future reactors have to operate under higher service temperatures (up to 500øC) and higher hydrogen pressures (up to 200 bar); these conditions can only be met with new steel grades. The objective of this project is to assess and predict the behaviour of welded components, made from the new steel grades, and to reach code acceptance. The experimental work comprises weldment optimisation, and the determination of the effect of creep, hydrogen attack, and the combination of these factors under the operating conditions. The theoretical part will use the data to develop and adjust a computer model, which will be used to predict and extrapolate the material behaviour under service conditions, and which can be applied for the accurate assessment of the (residual) life of hot hydrogen vessels. The potential benefits of this work are: - increase of the conversion yield and efficiency of the hydrotreating processes, - increased market share of advanced base materials, welding consumables and pressure vessels for the European manufacturers, - enhanced safety control and prevention of damage, which will result in an increased availability of the plant and reduced maintenance costs, - the higher grade materials enable significant reduction of the wall thickness of the reactor vessels, resulting in lower weights and reduced manufacturing costs, - the acceptance of new design codes, consistent with of new European "EN" standards (under preparation). Economic impact for the European steel manufacturers, vessel manufacturers and petro-chemical industry is estimated to be approximately 100 MECU/year. These interests are reflected in the consortium for the project, which comprises the full value chain from material suppliers, via vessel manufacturers, to end-users, and research institutes. Because of the combined experience and facilities of the partners, the project is expected to be finalised successfully within 3.5 years. Fields of science agricultural sciencesagriculture, forestry, and fisheriesagriculturegrains and oilseedsnatural scienceschemical sciencesinorganic chemistryinorganic compoundsnatural scienceschemical sciencesorganic chemistryaliphatic compounds Programme(s) FP4-BRITE/EURAM 3 - Specific research and technological development programme in the field of industrial and materials technologies, 1994-1998 Topic(s) 0202 - New methodologies for product design and manufacture Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator Creusot-Loire Industrie SA EU contribution No data Address 56,Rue Clémenceau 71202 Le Creusot France See on map Total cost No data Participants (7) Sort alphabetically Sort by EU Contribution Expand all Collapse all AG der Dillinger Hütte Germany EU contribution No data Address 66748 Dillingen See on map Total cost No data Commission of the European Communities Netherlands EU contribution No data Address 1755 ZG Petten See on map Total cost No data Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek Netherlands EU contribution No data Address 501,Laan van Westenenk 501 7300 AM Apeldoorn See on map Total cost No data Nuovo Pignone Italy EU contribution No data Address Via Felice Matteucci 2 50127 Firenze See on map Total cost No data Petrogal - Petroleos de Portugal SA Portugal EU contribution No data Address Leça da Palmeira 4456 Matosinhos See on map Total cost No data Shell International Oil Products BV Netherlands EU contribution No data Address 3,Badhuisweg 3 1031 CM Amsterdam See on map Total cost No data Technische Universiteit Delft Netherlands EU contribution No data Address 2,Mekelweg 2 2628 CD Delft See on map Total cost No data
