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Cartago City is located in the central valley of Costa Rica. Situated at the southern foot of the Irazu volcano and characterized by rugged mountainous topography, the city in general is exposed to multiple natural hazards including floods, volcanic eruption, and pyroclastic flows. Indeed, the city has experienced catastrophes in 1724, 1861, 1891, 1928, and 1951. The most recent one was a combination of pyroclastic flows and several floods in 1963–1964. This catastrophe caused US$3.5 million of economic damage as well as 20 deaths (ICE, 1966).

4 Heat exchanger experiments To study the performance of the ferritic 18 Cr‐2 Mo steel under actual heat exchanger conditions, large scale model heat exchangers were fabricated. After experiments to fabricate heat exchanger plates under standard stretch‐forming conditions, our investigations were confined to heat exchangers of the tubular type.

1 Introduction Some interesting new developments have taken place in recent years in the field of ferritic stainless steel (1–16). As a material for chemical apparatus, the common highly alloyed chromium steels as listed in national standards (e.g. in the German Standard DIN 17440) have only found limited applications. The reasons are sensitivity of several of these chromium alloyed stainless steels to intergranular corrosion (especially after welding), lower corrosion resistance compared to austenitic stainless steels, and difficulties in fabricating (especially welding). It has been shown (1–16) that the intrinsic drawbacks of customary ferritics can be overcome by metallurgical measures, primarily keeping the amount of carbon and nitrogen extremely low. The solubility in the ferrite for these two elements in rather low, both occupying interstitial sites. Stainless steels of the type dealt with in this paper are therefore sometimes termed Extra Low Interstitial (ELI)‐ferritic stainless steels. At sufficiently low concentrations of carbon and nitrogen (and some other elements), the sensitivity of ferritic stainless steels to intergranular corrosion is definitely lowered, and their ductility at ambient temperature is increased, i.e. the transition temperature is lowered. An advantage of these steels is their resistance to stress corrosion cracking. They have, so far, shown no sensitivity against chloride stress corrosion cracking under realistic operating conditions. For this reason, cooling water systems using river water with a high chloride content represent a suitable field of application for these steels. They can be welded up to a wall thickness of 3mm without sensitisation and undue loss of impact strength so that tubes for heat exchangers can be made of these steels. Their development has led to alloys ranging from 18 Cr‐2 Mo‐0 Ni to about 28 Cr‐2 Mo‐4 Ni. The present paper will only deal with the 18 Cr‐2 Mo steel because this material can be compared in price and properties with the standard 18 Cr‐9 Ni‐2 Mo austenitic stainless steel. In addition, the material in question has now become available in the form of pipe and sheet.

One important element for effective local disaster risk management (DRM) is community participation. However, this is not automatic in Costa Rica. Moreover, communities do not always continue DRM activities after a project or promotional campaign by the government. Indeed, little knowledge exists regarding long-term project sustainability of local DRM activities. Based on this, the present chapter discusses whether and how communities realize long-term DRM activities, an important factor for enhancing local DRM capacity, in a sustainable manner. The study conducts semi-structured interviews in the communities in Cartago City, Costa Rica as a means of evaluation; these are communities where the local DRM project has been implemented for more than ten years.

This study aims to identify the gaps in current policy and propose a viable framework for policy improvement regarding people-centered tsunami early warning chain in Padang City. The objectives are: to describe the gaps and flaws in the current policy regarding local tsunami early warning chain, to identify potential actors to be involved in the tsunami early warning chain and to assess the roles and capacity of actors, and their potential for involvement in early warning.

This study is an exploratory study using social network analysis (SNA) on regulations and other legal documents, and primary data sources from a focus group discussion and semi-structured interviews.

The study found that the existed regulation lacks extension nodes to relay warnings to the populations at risk, often referred to as “the last mile.” Moreover, receiving warning information from both formal and informal sources is important to mobilize people evacuation more effectively during an emergency. The study found that mosque communities and disaster preparedness leaders are the potential actors who should be involved in the local early warning chain.

The research findings were presented as a recommendation to Padang City Government and have been legalized as the new tsunami early warning chain procedure in the Padang City Mayor Regulation 19/2018.

This research investigated local tsunami early warning dissemination in Padang City using SNA. The study demonstrates a close collaboration between researchers, practitioners and the community.

The purpose of this paper is to investigate the electrochemical corrosion behavior of type 444 stainless steel (SS) in synthetic tap water from 25°C to 80°C, i.e. the operation environment of the electric water heater.

The corrosion behavior was studied by using electrochemical measurements such as electrochemical impedance spectroscopy and polarization curve. The specimen surfaces were observed with scanning electron microscopy. The passive films were characterized with X-ray photoelectron spectroscopy.

In the typical tap water, 444 SS passivates spontaneously under different temperatures. The passive films formed at higher temperatures contain relatively less Cr-species and more Cl⁻ ions, resulting in lower polarization resistances. The stable pitting corrosion takes place in the potential region of oxygen evolution as the temperature increases to about 55°C. The critical Cl⁻ concentration of pitting corrosion reduces from about 160 mg L⁻¹ to 60 mg L⁻¹ with changing temperature from 25°C to 80°C.

The pitting corrosion probability was assessed through the statistical analysis of tap water quality. The results are useful for the application of 444 SS as well as the design of electric water heater.

This paper shows the variation of polarization resistance, pitting potential, passive film composition and critical pitting chloride concentration with the temperature of tap water. It is of great significance for the development and application of SS in tap water environments.

PITTING CORROSION generally takes the form of localised corrosive attack at closely defined points, whose area constitutes only a minute part of the total surface of the steel. The considerably higher rate at which the steel goes into solution at these points causes the cavities to grow in depth, and may ultimately result in perforation. Fig. 1. The rate of pitting corrosion is largely determined by the proportion of the total cathodic to the total anodic area. The anodic current and the cathodic current flowing in the corrosion cell are equal.

Super304H steel is a new fine-grained austenitic heat-resistant stainless steel developed in recent years, and it is widely used in high temperature section superheater and reheater tubes of ultra-supercritical thermal power units’ boiler. Currently intergranular corrosion (IGC) has occurred in a few austenitic stainless steel tubes in ultra-supercritical units and led to boiler leakage. The purpose of this paper is to find a nondestructive method to quickly and easily detect IGC of austenitic stainless steel tube.

This paper uses the nonlinear characteristics of ultrasonic propagation in steel tube to detect the IGC of Super304H tube.

The experimental results show that the nonlinear coefficient generally increases sensitively with the degree of IGC; hence, the nonlinear coefficient can be used to assess IGC degree of tubes, and the nonlinear coefficient measurement method is repeatable for the same tube.

A theory of how IGC would affect the ultrasonic signals and lead to a nonlinear response needs further research.

A nondestructive method to quickly and easily detect IGC is provided.

Using ultrasonic nonlinear coefficient to assess IGC degree of tubes is a new try.

This paper provides a new way to test IGC.

Damage of engineering structures is a nonlinear evolutionary process that spans across both material and structural levels, from mesoscale to macroscale. This paper aims to provide a comprehensive review of damage analysis methods at both the material and structural levels.

This study provides an overview of multiscale damage analysis of engineering structures, including its definition and significance. Current status of damage analysis at both material and structural levels is investigated, by reviewing damage models and prediction methods from single-scale to multiscale perspectives. The discussion of prediction methods includes both model-based simulation approaches and data-driven techniques, emphasizing their roles and applications. Finally, summarize the main findings and discuss potential future research directions in this field.

In the material level, damage research primarily focuses on the degradation of material properties at the macroscale using continuum damage mechanics (CDM). In contrast, at the mesoscale, damage research involves analyzing material behavior in the meso-structural domain, focusing on defects like microcracks and void growth. In structural-level damage analysis, the macroscale is typically divided into component and structural scales. The component scale examines damage progression in individual structural elements, such as beams and columns, often using detailed finite element or mesoscale models. The structural scale evaluates the global behavior of the entire structure, typically using simplified models like beam or shell elements.

To achieve realistic simulations, it is essential to include as many mesoscale details as possible. However, this results in significant computational demands. To balance accuracy and efficiency, multiscale methods are employed. These methods are categorized into hierarchical approaches, where different scales are processed sequentially, and concurrent approaches, where multiple scales are solved simultaneously to capture complex interactions across scales.