FEM-Based Comparison of Mandrel Wear Resulting from Elongation of Pipes Manufactured from Various Materials on a Two-Roll Screw Rolling Mill

The present article discusses the cylindrical mandrel wear change during rolling using MISIS - 130 D mill depending on the type of rolled billets materials used. The research on the mandrel wear of the screw rolling mill during pipes elongation was carried out using the finite element method (FEM). The results of the wear modeling showed that the depth of the metal removed on the mandrel surface during stainless steel pipes elongation was higher as compared to alloyed and carbon steel pipes. The significant wear of the mandrel during stainless steel pipe rolling can be explained by the rise in the applied metal force resulting from the introduction of alloying components such as chromium and nickel into rolled billets materials. Consequently, the obtained modeling results can allow predicting the service life of working tools.

On-Line Monitoring of Biofilm Accumulation on Graphite-Polypropylene Electrode Material Using a Heat Transfer Sensor

Biofilms growing on electrodes are the heart piece of bioelectrochemical systems (BES). Moreover, the biofilm morphology is key for the efficient performance of BES and must be monitored and controlled for a stable operation. For the industrial use of BES (i.e., microbial fuel cells for energy production), monitoring of the biofilm accumulation directly on the electrodes during operation is desirable. In this study a commercially available on-line heat transfer biofilm sensor is applied to a graphite-polypropylene (C-PP) pipe and compared to its standard version where the sensor is applied to a stainless-steel pipe. The aim was to investigate the transferability of the sensor to a carbonaceous material (C-PP), that are preferably used as electrode materials for bioelectrochemical systems, thereby enabling biofilm monitoring directly on the electrode surface. The sensor signal was correlated to the gravimetrically determined biofilm thickness in order to identify the sensitivity of the sensor for the detection and quantification of biofilm on both materials. Results confirmed the transferability of the sensor to the C-PP material, despite the sensor sensitivity being decreased by a factor of approx. 5 compared to the default biofilm sensor applied to a stainless-steel pipe.

Fabrication of Low Roughness Gradient Nanostructured Inner Surface on an AISI 304 Stainless Steel Pipe via Ultra-Sonic Rolling Treatment (USRT)

Gradient nanostructure (GNS) has drawn great attention, owing to the unique deformation and properties that are superior to nanostructure with uniform scale. GNS is commonly fabricated via surface plastic deformation with small tips (of balls or shots) so as to produce high deformation to refine the coarse grains, but unfortunately it suffers from the deterioration of surface quality that is which is hard to guarantee the reliable service. Although there are mirror-finishing techniques that can greatly enhance the surface quality, the induced slight deformation is commonly unable to produce GNS of reasonable thickness. Here, we propose a method to fabricate a GNS surface layer with a substantially enhanced surface quality via ultra-sonic rolling treatment (USRT), namely, surface rolling with a roller vibrated at a frequency of 20,000 Hz. It is found that 4-pass USRT is able to produce 20–30 µm thick GNS on AISI 304 stainless steel pipe inner surface, wherein the surface quality is enhanced by one order of magnitude from the starting Ra = 3.92 µm to 0.19 µm. Processing by a roller with a high-frequency vibration is necessary for both good surface quality and the effective accumulation of heavy deformation on the surface. The flattening mechanism as well as the microstructural evolution from millimeter- to nanometer-scale for AISI 304 stainless steel is discussed.

Microbial Characteristics of the Combined Ozone and Tea Polyphenols or Sodium Hypochlorite Disinfection in the Pipe Network

Microbiological safety of water in the pipe network is an important guarantee for safe drinking water. Simulation tests of stainless steel pipe network were carried out using te4a polyphenols and sodium hypochlorite as auxiliary disinfectants for ozone disinfection to analyze the persistent disinfection effects of different combined disinfection methods by measuring the changes in total bacterial colonies in the water. High-throughput sequencing of microorganisms in the pipe network was performed to analyze the differences in the community structure of microorganisms in the water and pipe wall under different disinfection methods. The results showed that the application of auxiliary disinfectants had a relatively long-lasting inhibitory effect on the bacterial colonies in the water, and the diversity of microorganisms in the pipe network varied significantly. As an auxiliary disinfectant for ozone disinfection, tea polyphenols are more powerful than sodium hypochlorite in killing pathogens and chlorine-resistant bacteria, so they are more beneficial to ensure the microbiological safety of water in stainless steel pipe networks.