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Investigations of sand-water induced erosive wear of AISI 304L stainless steel pipes by pilot-scale and laboratory-scale testing
Get PDFThe repair costs of erosion damage caused by solid particle impingement from transporting slurries and other particle-laden liquids in pipes can be extremely high. In the absence of accurate predictive models, routine monitoring of the pipe wall thickness or the use of sacrificial coupons are required to warn of erosion damage or impending loss of containment. Apart from advantages for plant maintenance, the environmental, safety and production implications are enormous. Identification of critical pipe components susceptible to high levels of damage, and innovative ways to ameliorate the damage, has been an active topic of research for decades. Recent work at University of Nottingham and University of Southampton [Wear 250 (1–12) (2001) 771] has sought definitions of flow fields and particle dispersions and their relationship to erosive wear to facilitate the development of new designs and geometries for slurry handling equipment.This paper covers research that has been aimed at determining the distribution of erosion rates and the erosion mechanisms that occur over wetted surfaces within pilot-scale pipe systems handling water–sand mixtures at 10% by volume concentrations and at a mean fluid velocity of approximately 3 m/s. Experiments are presented which have been conducted on a test section consisting of an upstream straight pipe section followed by a bend (with a radius of curvature of 1.2 bore diameter) within a 78 mm diameter pipe test loop. The whole loop and test section was manufactured from AISI 304L stainless steel. The wall wear rates, obtained by gravimetric measurements, as a function of time are discussed. Circumferential erosion penetration and mechanisms at discrete locations have been measured by surface profilometry on replicas and scanning electron microscopy after cutting-up the pipe sections. The erosion rates and patterns are compared to those predicted by erosion models linked to computational models for the impact velocity and impact angle in bend and straight sections. Bend wear patterns are further compared to flow visualisation results from a transparent flow loop and electrical resistance tomography (ERT) to confirm the placement of particle burdens. The erosion rates, expressed as volume loss per impact (determined gravimetrically and via computer models) in bends are found to agree well with simple laboratory-scale water–sand jet impingement tests on planar stainless steel samples. The pipe loss data alone represents a significant resource for future erosion researchers to reference
Upstream swirl-induction for reduction of erosion damage from slurries in pipeline bends
No full textIndustries which transport slurries and other particle-laden liquids in pipes expend the equivalent of millions of pounds every year to repair erosion damage caused by solid particle impingement. It is against this background that the perceived relationship between pipeline erosion and imposed swirling flow fields in pipe bends is important. Definitions of flow fields and particle dispersions which minimise erosive wear are sought to facilitate the development of new designs and geometries for slurry handling equipment. Such an approach is pertinent to industries handling valuable or hazardous material in the face of increasing safety, efficiency and economic requirements. Robust erosive wear models must be developed to explore the advantages of swirl flow and subsequent particle dispersion.Collaboration between the universities of Nottingham and Southampton is aimed at the reduction of wear at critical locations in slurry handling pipelines by applying swirl-inducing pipes upstream of pipe bends. This paper details the improved particle distributions, particle impingement conditions and lower flowrates resulting from such swirl flow. These factors are discussed in terms of current erosion models and the predicted reduction in wear rates. Parallel visualisation studies using simulant particle-laden liquids augment computational modelling of the flow patterns
Comparison of predicted and experimental erosion estimates in slurry ducts
No full textComputational models for the impact velocity and impact angle in a bend have been successfully applied to the flow field and validated by electrical resistance tomography (ERT) to confirm the position of particle burdens. Particle impact parameters from this work have been used as inputs to erosion models to predict wall wastage rates in a Rc/D=1.2 bend and a upstream straight pipe section. The location of damage and the levels of wall wastage agree well with those obtained from erosion trials conducted on a full scale loop rig with AISI 304 stainless steel pipework. Well-distributed but asymmetric particulate flows of sand in water have been studied at average flow velocities of 3 m s?1. Predicted erosion damage levels and locations are compared to non-destructive ultrasonic and gravimetric measurements as well as wall thickness measurements made with a micrometer after cutting the pipe and bends sections
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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