Giacobbe F.,ISPESL |
Mazzocchi V.,ISPESL |
Engineering Failure Analysis | Year: 2010
Reformer furnaces are used in petrochemical industry to produce hydrogen. Their most critical components are radiant tubes, where extreme temperature and pressure conditions required the deployment of high alloyed austenitic HP grade steels, owing to their superior strength to creep rupture and good corrosion resistance. Nevertheless, these high strength alloys undergo damage when process conditions allow coke deposition and maintenance procedures are not carried properly.Two radiant tubes, coming from two different plants and made of HP40Nb and HP40Nb microalloy steels respectively, are investigated here to highlight the endured damage after 85,000-96,000. h of service at maximum temperature of ∼950°C. Light optical microscopy (LOM) and scanning electron microscopy (SEM) analyses both confirmed significant aging in both tubes, as revealed by a substantial microstructural evolution consisting of phases transformation and precipitation, as well as cavitation and incipient microcracking in the bulk. Mechanical testing demonstrated the considerable worsening of mechanical properties following such a microstructural deterioration.However, noticeable differences between the two tubes were discovered as far as type and distribution of damage, and extent of the aged zone. The small differences in alloys composition seem not sufficient alone to explain such dissimilarity in behaviour because, in addition to creep damage, one tube showed also clear evidence of carburization. Instead it is argued that differences in process conditions (i.e. temperature, pressure chemical composition of process fluids and steam-hydrocarbon ratio) and cleaning maintenance for decoking (i.e. type and frequency) may have synergistically triggered different damage mechanisms responsible for the different form of degradation on each reformer tube. © 2010 Elsevier Ltd.
Traversi D.,University of Turin |
Villa S.,University of Turin |
Acri M.,SMAT S.p.A. |
Pietrangeli B.,ISPESL |
And 2 more authors.
AMB Express | Year: 2011
Methanogen populations and their domains are poorly understood; however, in recent years, research on this topic has emerged. The relevance of this field has also been enhanced by the growing economic interest in methanogen skills, particularly the production of methane from organic substrates. Management attention turned to anaerobic wastes digestion because the volume and environmental impact reductions. Methanogenesis is the biochemically limiting step of the process and the industrially interesting phase because it connects to the amount of biogas production. For this reason, several studies have evaluated the structure of methanogen communities during this process. Currently, it is clear that the methanogen load and diversity depend on the feeding characteristics and the process conditions, but not much data is available. In this study, we apply a Real-Time Polymerase Chain Reaction (RT-PCR) method based on mcrA target to evaluate, by specific probes, some subgroups of methanogens during the mesophilic anaerobic digestion process fed wastewater sludge and organic fraction of the municipal solid waste with two different pre-treatments. The obtained data showed the prevalence of Methanomicrobiales and significantly positive correlation between Methanosarcina and Methanosaetae and the biogas production rate (0.744 p < 0.01 and 0.641 p < 0.05). Methanosarcina detected levels are different during the process after the two pre-treatment of the input materials (T-test p < 0.05). Moreover, a role as diagnostic tool could be suggested in digestion optimisation. © 2011 Traversi et al; licensee Springer.
Franzetti A.,University of Milan Bicocca |
Gandolfi I.,University of Milan Bicocca |
Raimondi C.,University of Milan Bicocca |
Bestetti G.,University of Milan Bicocca |
And 5 more authors.
Bioresource Technology | Year: 2012
The aims of this work were the characterisation and the evaluation of potential environmental applications of the bioemulsifiers produced by Variovorax paradoxus 7bCT5. V. paradoxus 7bCT5 produces a mixture of high molecular weight polysaccharides. The extracellular bioemulsifiers were able to produce a thick stable oil/water emulsion and maintained the emulsification activity after boiling and at low temperatures. Environmental behavior and impact of bioemulsifiers release were assessed by evaluating biodegradability, toxicity and soil sorption. Respirometric tests showed that moderate biodegradability occurred by soil bacterial inoculum. Furthermore, the produced compounds did not show any toxic properties through different ecotoxicological tests. The K d values ranged from 1.3 to 7.3L/kg indicating a high sorption affinity of the bioemulsifier molecules to soil particles. The soil sorption affinity likely affected the bioemulsifier ability to remove hydrocarbons from contaminated soils. In fact, V. paradoxus 7bCT5 bioemulsifiers significantly increased the removal of crude-oil from sandy soil compared to water. © 2012 Elsevier Ltd.
Giornale Italiano di Medicina del Lavoro ed Ergonomia | Year: 2010
Legislative decree n.81 of 9 April 2008 promulgated pursuant to article 1 of law n.123 dated 3 August 2007 and amended by Legislative Decree n. 106 of 3 August 2009 - is the legislative text that changed the field of health and safety at work. This Text represents the mainstream of national legislation to protect workers against work's diseases. The B-BS system is a technique based on scientific disciplines that allows to modify behaviors related to safety, to reduce the influence of the human error component in the dynamics of most accidents. The aim of this article is to make a comparison between the requirements outlined by D.lgs. 106/09 and the implementation of protocols for B-BS in business, highlighting critical issues and possible contact points. Although it is strictly necessary to apply the legislative decree by the companies, it is also important for the workers to perform safe behaviors, according to the same dictates of legislation. For this reason it is essential to analyze the compatibilities between the legislative text (D.lgs 106/09) and the B-BS system, to create a multidisciplinary culture of safety and to build safer and healthier work environments. © PI-ME, Pavia 2010.
Materials at High Temperatures | Year: 2010
New non-destructive examination methods have been available for many years. These include time of flight diffraction and phased array methods. These are routinely used for inspection of welds. Work is ongoing at ISO and CEN for standardization of these methods. First the time of flight diffraction was drafted and now ISO and CEN are working on a standard for phased arrays. These drafts are used for welding inspections. The acceptance criteria is in draft form for time of flight diffraction which will be followed by that for phased array. Standards are already available for base material phased array inspection such as the ASTM document ''Standard Guide for Evaluating Performance Characteristics of Phased Array Ultrasonic Examination Instruments and Systems''. Several ASME code-cases have been issued in recent years on weld inspection. Qualification for the ASME code is also planned for this novel technique. © 2010 Science Reviews 2000 Ltd.
Rondinone B.M.,ISPESL |
Boccuni F.,ISPESL |
Scandinavian Journal of Work, Environment and Health | Year: 2010
Objectives: In 2000-2001, the Italian National Institute for Occupational Safety and Prevention (ISPESL) carried out a survey to identify the research priorities in the field of occupational safety and health (OSH). The present study, carried out in 2007-2008, was a follow-up designed to (i) review the themes identified earlier, (ii) detect emerging issues linked to new risks and forms of work, and (iii) look for any shifts in focus. The survey was extended to cover not only research but also the concept of knowledge transfer. Methods: In the first round, ISPESL distributed questionnaires to the heads of both university occupational medicine departments and prevention departments in local national health units (known as ASL in Italy) asking respondents to identify OSH priority themes. In the latest survey, covering both research and the need for knowledge transfer, the same experts were asked to rank the importance of the earlier-identified topics and list any emerging issues in the OSH field. Results: The two most important themes identified were "work accidents" and "occupational carcinogenesis". In the overall sample and among ASL experts, they received the 1st and 2 nd highest mean scores. The university respondents also prioritized them but in reverse order. Some of the new priority topics included: risks associated with nanotechnologies; assessment of psychosocial and organizational risks; migration and work; and cost-benefit analysis of prevention. Conclusion: In light of the findings, efforts are urgently needed to identify research and knowledge transfer priorities related to workers' health and safety on an international scale using a standardized method in order to obtain comparable results, avoid wasteful duplication of resources, and reduce occupational accidents and illness.
Giornale Italiano di Medicina del Lavoro ed Ergonomia | Year: 2010
The 81/08 Decree gives a strategic role to the processes that provide information, knowledge and training, regarded as fundamental measures to improve health and safety conditions in the workplace. The most important aim of health and safety training is to acquire skills to carry on duties according to safety principles in the company. Competence consists of the possession and application of integrated knowledge, skills and behaviors. To achieve these results, it is essential the desire of the organization, at all levels, to invest on learning and development, highlighting the benefits arising from the adoption of safe behavior by workers. Different methodologies contribute to this aim, including those developed within the behavioral sciences, such as the BehaviorBased Safety (B-BS), which is based on the development of safe behaviors, through the implementation of a registration system for behavior, feedback and positive consequences. This report will make a comparison between the elements that characterize health and safety training provided by the D. Lgs. 81/08 and the enforcement of protocols for B-BS in companies. © PI-ME, Pavia 2010.
Bragatto P.A.,ISPESL |
Agnello P.,ISPESL |
Ansaldi S.M.,ISPESL |
Journal of Loss Prevention in the Process Industries | Year: 2010
At Seveso plants, duty holders must have a complex system for assessing and managing risks. The pillars of this system are the safety report and the safety management system, with a number of underlying documents. The strength of the system is the high standardization of these documents. Regulations, standard codes and guidelines define content, structure and formats. The weakness is the high complexity. Managers and workers perceive documents as difficult to understand and far from actual operations. Major threats for the credibility of documents (and therefore for the safety systems) come from the continuous organizational and technical changes, which in a short time can make most documents obsolete; as well as by near misses, which continuously show the holes in safety systems. A big effort is required to follow up the plant changes and the near misses. In order to help safety managers, a new software has been developed. At Seveso plants, it has been possible build an integrated digital representation, because all documents are perfectly structured. This representation may be used both for updating the relevant documents after a change and to improve documents after a near miss or an accident. In this way, safety documents are always up to date and trustworthy and the huge knowledge, which is usually hidden inside safety documents, is clearly revealed and revived. The approach is basically "knowledge based" and the intention is to provide safety managers with an easy and simple tool. IRISonLine is a software that has been developed by ISPESL to provide safety managers of "Seveso" establishments with a tool for improving the management of change and of near misses. © 2010 Elsevier Ltd.
International Journal of Pressure Vessels and Piping | Year: 2010
EN12952-4 provides a method for calculation of in-service low cycle fatigue damage. The procedure describes the calculation of low cycle fatigue damage of boiler components during operation. Temperature, pressure, temperature differences, strain, etc. are considered in the determination of actual damage level.The EN12952-4 also includes creep calculation and creep-fatigue combined calculation, but this part, essential for Remaining Life Assessment, it is not in the scope of this paper.The European standard provides also calculation examples, even if only by computer data logging system it is possible to apply the procedure.Fatigue calculation, as well as creep and creep-fatigue calculation, is essential for modern HRSG plants, where the changing of operational conditions is quite often applied. © 2010 Elsevier Ltd.
Engineering Fracture Mechanics | Year: 2010
The 21/4Cr1Mo (P22) is present in most of structural high-temperature applications, as results from a review on materials employed for the construction of both power and chemical plants. So, it fits well for an experimental activity in the laboratory as reference material. ISPESL, the Italian Certification Agency, carried out a low-budget program of creep and low-cycle fatigue (LCF) tests at 550 °C; the specimens (twelve plus two spare) of as-fabricated material came from a thick-wall pipe with a certified circumferential weld. They were base metal and cross-weld fusion-line centered ones. Comparison of the resistance curves obtained from LCF tests with those from codes (ASME and ISPESL) showed for the base metal good correspondence; therefore, showed the reliability of the test proceeding. For the weld it showed instead conservatism reduction at high-strain levels for the ASME design curve; moreover, it revealed an insufficient conservatism of the reduction factor proposed, which is 1/2, for the lower bound ISPESL curve. Comparison of the resistance curves obtained from creep tests with those from codes showed this: for both the base metal and weld there are a good correspondence and acceptable (low) conservatism of the strength reduction factor (SRF) proposed; for the load and temperature levels considered in the tests, it equals one. Still, the creep tests duration was within thirty hundred hours each; therefore the levels of the applied load (150.2-100. MPa) were not as low as those in typical operation conditions. For these cases, the code (ASME) proposes a lower-than-unity SRF: thus, longer tests (lower levels of the applied load) would be useful, also extending the activity to other materials. © 2010 Elsevier Ltd.