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Wear behavior of boronized GGG‐80 ductile cast iron were studied against WC‐Co ball for determining the effect of boronizing time and temperature.

Ball on disk arrangement was used for determination of tribological properties of boronized ductile cast iron depending on process time and temperature. Boronizing treatment was performed on GGG‐80 ductile cast iron using salt bath immersion boronizing technique at 850 and 950°C for 2‐8 h. Friction and wear tests were carried out at dry test conditions under 2, 5 and 10 N loads with 2.5 m/min sliding speed.

The result showed that the friction coefficient values ranged from 0.12 to 0.2 depending on the process parameters. The higher the treatment temperature and the longer the treatment time, the thicker the boride layer, the more the FeB phase and the higher the specific wear rate became. The specific wear rate of boronized ductile cast irons depending on process time, temperature and applied load against WC‐Co ball ranged from 1.25 × 10⁻⁵ to 42.45 × 10⁻⁵ mm³/Nm. Values of coefficient of boronized ductile cast irons increases with increase in load in the wear test and increase in boronizing time and temperature.

The study deals with only ductile cast irons and their tribological properties.

The results are very useful for practical applications and academic study. There is a little number of studies on the boronizing of cast irons. This study will be helpful for the researcher studied on boronizing of cast irons.

The properties of the tribological properties of ductile cast irons have not explained detail in the earlier study. There are new results in this study on the tribological properties of boronized ductile cast irons. Because of this, the paper is original.

Pipeline systems throughout the world have been receiving increased attention over the last few years. In part, this has been due to the rise in use of new materials, but it is also the result of the growth in awareness of the need for a reliable supply of clean, potable water.

The purpose of this paper is to analyze conditional failure rates, and prioritize water pipelines for replacement based on their expected failure rate where pipes are grouped based on age and pipe type. Thus, predictions can be made on the expected number of breaks in future years.

The time to failure of a pipe can be characterized by the stochastic properties of the population as a whole, from which the likelihood of component failure is derived. When the corresponding failure rate is plotted against time, a bathtub‐shaped curve results. The bathtub curve assists in determining maintenance schedules depending on the age of the pipe. Failure rates help determine whether the rates are more than an acceptable best practice threshold to signal replacement.

Ductile iron pipes had the highest failure rates, followed by asbestos cement pipes; PVC and concrete cylinder pipes had the lowest failure rates, but because concrete cylinder pipes are very time‐consuming to repair and very expensive to install, only PVC pipes are recommended on the basis of this study. Cast iron pipes fit the bathtub shape; ductile iron and asbestos concrete were somewhat bathtub shaped, though the early phase period was not apparent; the bathtub curve for concrete cylinder was fully inverted; while PVC pipes showed zero probability of failure during the middle period. The shapes of bathtub curves drawn on conditional failure rates were similar to those for the failure rates. The bathtub curves indicate that the general failure performance of pipe materials is somewhat contrary to general principles in manufacturing.

Analysis of failure serves a practical purpose for water utilities to allocate funds for pipe maintenance and prepare a schedule for pipe replacement, so as to provide the best quality services and safe drinking water to users of the utility.

The proper prioritization of water supply pipes for repair and replacement is of great social importance to the public at large, which expends considerable funds to maintain their drinking water supply.

The study of bathtub curves has not been seen before in the analysis of water supply pipes. A unique discovery is that the traditional shape of the bathtub curve is not always applicable for water supply pipes.

The purpose of this paper is to investigate performance times from a quality engineering perspective for response and repair of pipes at a public utility. The objective is to scientifically determine the pipe that offers the most desirable downtime (DT) and time to repair (TTR).

Four types of water supply pipes – concrete cylinder (CC), cast iron (CI), ductile iron (DI), and polyvinyl chloride (PVC) – in prevalent use at the City and County of Honolulu Board of Water Supply were analyzed to determine the pipe type that is most consistently repaired to desired performance specifications. Data for mean downtime (MDT) and mean time to repair (MTTR) were used to evaluate the stability and capability of the repair processes for each pipe type. The analysis was completed through the use of control charts, operating characteristic (OC) curves, and process capability indices.

The results of the analysis indicated that CI pipes were the worst material in terms of DT and TTR. The control charts for MDT for all pipe types, and the MTTR for CI and CC pipes, were found to be out of statistical control, but the control charts for the MTTR of DI and PVC pipes were discovered to be in control. According to the OC curves, in which the hypothesis stated that the average MDT or MTTR was between the specification limits, there was a high tendency in all pipe types to accept the hypothesis when it was true. However, the probability of type I errors was high from operational standards at the USL level. Process capability analyses found that only CC pipes were able to meet performance design specifications; however, repair times are extremely large for CC pipes. Overall, it is recommended that CI pipes be replaced when the opportunity arises.

This investigation serves to address a major query in asset management at the public utility, that of which pipes should be selected during design and procurement from a maintenance perspective. In addition, the study helps to understand the trend of DT and TTR for the various pipes.

Quality water supply is of paramount social importance in modern cities.

A quality engineering approach to asset management for pipe systems at public utilities that serves to add a new dimension to asset performance analysis is adopted.

Materials Science and Technology Although corrosion is not specifically mentioned in the terms of reference of the recently announced Working Party on Materials Science and Technology formed under the auspices of the Institution of Chemical Engineers, it obviously must be one of the subjects for consideration. It is interesting to note the careful balance between theory and practice maintained when choosing the members of this Working Party, as only too often in such projects is the tendency towards overlooking the latter in favour of the former. That this is not so may be seen from the fact that approximately one‐third of the members are academic, the remainder being from research associations and industrial and national laboratories. Also, some 20% belong to the Institution of Chemical Engineers. Another important feature which should ensure success is the wide variety of interests of the industrial members, these including paper, concrete, rubber, plastics, ceramics, glass and, of course, metals.

Underground cast iron and steel pipelines are used for the conveyance of potable water for domestic supply and steel pipelines are used to transport fresh water in fire water mains in both installations onshore and on offshore oil and gas platforms. Seawater is conveyed by pipeline for industrial cooling applications.

Summary Corrosion is not a new phenomenon. It is only recently, however, that the damage it causes has been fully recognised. The cost must not only be measured in the metal destroyed, but the enormous cost of replacement, maintenance and repair.

U.S.S.R. Oxygen and nitrogen in metallised surfaces. One of the most important considerations in the matter of extending the life of units or components under rolling friction conditions or corrosion is the use of different pseudo‐alloys on a steel base, and the chemical composition and nature of these ‘alloys,’ especially in the matter of oxygen and nitrogen content. Electro‐metallising is briefly described. The micro‐structure of a steel metallised pseudo‐alloy is shown and discussed. Characteristic features are porosity and heterogeneity, the former amounting to 10 to 15%. Methods of analysis, especially for oxygen and nitrogen, include anodic solution and separation of non‐metallic inclusions (including oxides) in powder form. Nitrogen content averaged 0.13% and oxygen 2.7% (without manganous oxide). An x‐ray study was made of the phase constitution of non‐metallic inclusions, with tabulated results and x‐ray photographs. Analyses of the pseudo‐alloys for carbon manganese, sulphur, phosphorus and silicon are also tabulated. —(L. V. Krasnichenko et al., Zh. prikl. Khim. (J. Appl. Chem.), 1958, (8), 1170–1174.)

The results of a study of friction welding of ductile cast iron using stainless steel interlayer are presented. Based on the microstructure evolution at the region close to the ductile cast iron‐stainless steel interface, the phenomena accompanying the process of joining were evaluated. Therefore, the purpose of this paper is to take a closer look into metallurgical phenomena accompanying the friction welding of ductile cast iron.

In this paper, ductile cast iron and austenitic‐stainless steel are welded using the friction welding method. The tensile strength of the joints was determined using a conventional tensile test machine. Moreover, the hardness across the interface ductile cast iron‐stainless steel interface was measured on a metallographic specimen. The microstructure of the joints was examined using light metallography as well as electron microscopy. In this case, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied. Energy Dispersive X‐ray analysis (EDS) was carried out across the section of friction welded ductile iron‐stainless steel interface.

On the basis of careful analysis of experimental data it was concluded that the process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the ductile cast iron‐stainless steel interface. This leads to an increase of carbon concentration in stainless steel where chromium carbides were formed, the size and distribution of which was dependent on the distance from the interface.

The main value of this paper is to contribute to the literature on friction welding of ductile cast iron.

The purpose of this paper is to inform facility managers of the type of failure affecting certain pipe types more than others. This is useful in asset management as preventive maintenance can be undertaken for those pipe types that experience high probabilities of failure.

The probability of a specific pipe type failing given the cause of break, age at failure, pipe diameter, and type of soil at the location of the break was found using inventory and main break data from the Honolulu Board of Water Supply (HBWS). Bayes’ theorem was then applied to find the posterior probabilities of failure starting from the prior probabilities of failure.

It was observed that the greatest probabilities of failure involved corrosion, pipes aged between 20‐30 years, 8″ pipes, and pipes in fill material. The pipe types were ranked and scored based on their probability of failing due to break cause, age, diameter, and soil type. Cast iron pipes were shown to have the highest probability of failing. As such, attention should be given to replace segments of cast iron pipes as they reach the end of their service lives.

This study serves to address a major query in asset management at a public utility, that of which pipes should be selected for replacement when they reach the end of their service life. In addition, this study helps to understand the causes of failure for the various types of pipe.

The importance of having reliable water supply at low cost has immense social implications in modern communities. To deliver such service, water pipe assets have to be managed efficiently.

This paper addresses the probability of failure in a straightforward manner that the water utility can easily apply to its own data, both in its design and asset management.