Meireles I.,University of Aveiro |
Renna F.,ATB Riva Calzoni Spa |
Renna F.,University of Bari |
Matos J.,University of Lisbon |
Bombardelli F.,University of California at Davis
Journal of Hydraulic Engineering | Year: 2012
The nonaerated region may occupy a large portion of the skimming flow in steep, stepped spillways, particularly for relatively high unit flow rates. In spite of the numerous contributions on the hydraulic properties at both the inception point of air entrainment and the aerated region, much less is known regarding the flow in the nonaerated region. In this paper, new empirical evidence, based on an extensive data set obtained during several years in a large-scale facility, sheds light on the features of the nonaerated-flow region. Diverse ways to locate and estimate the main hydraulic properties at the inception point are first discussed and compared. Then, expressions capable of characterizing the main flow variables along the nonaerated region are presented, namely, the boundary-layer development, the velocity distribution, the equivalent clear-water depth, the characteristic depth taking into account the free-surface unsteadiness due to turbulence, and the energy dissipation. The energy dissipation is observed to be larger than that for smooth spillways, although much smaller than values typically reported for aerated flows at the toe of stepped spillways. © 2012 American Society of Civil Engineers.
Renna F.M.,ATB Riva Calzoni SpA |
Zenocchini P.,ATB Riva Calzoni SpA |
Guerini A.,ATB Riva Calzoni SpA |
Fratino U.,DICATECH |
International Journal on Hydropower and Dams | Year: 2013
Howell Bunger valves are used widely as control structures and as emergency release devices because of their capacity to control the flow discharge and dissipate surplus energy. This paper, through the analysis of a large set of experimental data, deals with the main features of these valves, summarizing some observations which may help in improving the valve design. The main conclusions are based on the valve data collected during the experimental tests carried out jointly by the research teams of a primary valve manufacturer (ATB Riva Calzoni) and Politecnico di Bari. The results are compared with relevant literature.
Frizell K.M.,Bureau of Reclamation |
Renna F.M.,ATB Riva Calzoni SpA |
Renna F.M.,University of Bari |
Matos J.,University of Lisbon
Journal of Hydraulic Engineering | Year: 2013
Cavitation on spillways has proven to be an undesirable condition. The formation of vapor-filled bubbles and cavities and their eminent collapse has led to significant damage to major spillway components and appurtenant structures worldwide. Although stepped spillways are thought to be less prone to cavitation damage than smooth spillways, designers continue conservative practices regarding specifying stepped spillways at many sites. Using laboratory experiments in a specialized reduced ambient pressure chamber, cavitation was shown to form on stepped geometries that are representative of typical stepped spillways currently in service. Experiments in a nonaerated closed conduit revealed the strength and extents of the highly intense shear layer that forms above the step tips, and the friction characteristics were determined and compared with results from previous researchers. Advanced techniques for detecting cavitation characteristics along with high-speed videography have given additional insight into the flow features that drive the formation of cavitation. Finally, a correlation between the critical cavitation index and the common friction factor is shown, extending the data that also includes shear layers resulting from uniformly distributed roughnesses, jets, and wakes. © 2013 American Society of Civil Engineers.
Application of the specifications in ASME Code Case 2605-1 to verify the creep-fatigue interaction in pressure apparatuses made of 2.25Cr-IMo-V steel [Applicazione delle prescrizioni in ASME Code Case 2605-1 per la verifica dell'interazione creep - Fatica in apparecchi in pressione realizzati in 2.25Cr-IMo-V]
Guerra B.A.,ATB Riva Calzoni S.p.A. |
Cecchi A.,ENI S.p.A |
Grandicelli R.,IIS SERVICE |
Pagano S.,IIS SERVICE |
Cosso G.L.,ATB Riva Calzoni S.p.A.
Rivista Italiana della Saldatura | Year: 2011
In the latest edition of the ASME Code, criteria for fatigue assessment in pressure vessels manufactured with 225Cr-IMo-Vsteel are given up to operating temperatures not exceeding 371 °C (700 °F), whilst the design temperature typically adopted (454 °C) is significantly higher. In order to plug this gap, ASME has recently published the Code Case 2605-1, considering the interaction between fatigue and creep phenomena. Material creep behaviour is in particular represented through the "Omega" approach, recently introduced by the API 579-1/ASME FFS-I standard. This article has been written with the aim to present the application of Code Case prescriptions for the fatigue assessment of items F90101AIB (Hot High Pressure Separator), manufactured by ATB Riva Calzoni S.p A. on behalf of ENI R&M. In particular the manufacturing procedures followed in vessels construction and the numerical analyses performed for the assessment of components are described in detail, highlighting, with special attention, those features which mainly affect evaluation results.
Experimental characterization of the Electroslag Strip Cladding (ESSC) with Multi Strip technology, Twin type [Caratterizzazione sperimentale del processo di placcatura ad elettrdscoria (ESSC) con tecnica multi strip tipo Twin]
Sabattoli L.,ATB Riva Calzoni spa |
Lancini I.,ATB Riva Calzoni spa |
Volpi A.,ATB Riva Calzoni spa |
Alghisi J.,Welding Technology srl |
Garbarino G.,IIS Progress srl
Rivista Italiana della Saldatura | Year: 2015
The industrial process that combines increased productivity with controlled dilution is ESSC (Electroslag Strip Cladding). The paper aims to overcome the current ESSC process limitations, analyzing the possible benefits introduced by Multi Strip technology, Twin type. The tests with combinations of carbon steel coated with Alloy 625 and Type 347 deposit on creep resistant low alloy steel were conducted.