scholarly journals Effects of pipe materials on biofouling under controlled hydrodynamic conditions

2015 ◽  
Vol 6 (1) ◽  
pp. 167-174 ◽  
Author(s):  
S. Gamri ◽  
A. Soric ◽  
S. Tomas ◽  
B. Molle ◽  
N. Roche
Keyword(s):  
Growth Control ◽  
Surface Characteristics ◽  
Primary Role ◽  
Pipe Material ◽  
Hydrodynamic Conditions ◽  
Biofilm Growth ◽  
Pipe Surface ◽  
Biofilm Detachment ◽  
Pvc Pipe ◽  
Pipe Materials

Experiments were carried out to investigate pipe material impacts on biofouling, at high effluent concentration levels and under controlled hydrodynamic conditions. Two velocities (0.4 and 0.8 m s−1) were used to monitor biofilm growth on polyethylene (PE) and polyvinylchloride (PVC) pipe walls, respectively. These conditions were established based on wastewater irrigation practices. A decrease in biomass is observed after 49 days of experiments for both velocities and may be related to biofilm detachment. Biofilm growth is greater at 0.8 m s−1. For both velocities, PVC is less sensitive to biofilm growth than PE. Pipe straightness plays a primary role in biofilm growth control. This effect is more significant than pipe surface characteristics (roughness, hydrophobic/hydrophilic properties).

The interaction of a manganese-oxidising bacterium as part of a biofilm growing on distribution pipe materials

2000 ◽  
Vol 41 (4-5) ◽  
pp. 295-300 ◽  
Author(s):  
F. Murdoch ◽  
P.G. Smith
Keyword(s):  
Biofilm Formation ◽  
Bacterial Activity ◽  
Confocal Laser ◽  
Pipe Surface ◽  
X Ray ◽  
Pseudomonas Spp ◽  
Eds Analysis ◽  
Large Clusters ◽  
Pipe Materials ◽  
Confocal Laser Microscope

The deposition of manganese within a biofilm growing on the surface of high-density polyethlene (HDPE) and polyvinychloride (PVC) was studied over a period of four months. The manganese rich water used in the study was inoculated with a manganese oxidising Pseudomonas spp. The level of Mn2+ in the water was monitored and was found to decrease as the biofilm formation increased. This was confirmed by energy dispersive X-ray spectroscopy (EDS) analysis which showed the detection of manganese was dependent on the presence of a biofilm. After two months a 100% removal of Mn2+ was observed in all the flasks inoculated by the Pseudomonas spp. and manganese micro-nodules, the formation of which were reported in Murdoch and Smith (1999), were being formed in large clusters across the surfaces of both the HDPE and PVC. The manganese peak area from the EDS spectrum analysis of the micro-nodules was significantly larger than was measured in the biofilm when these micro-nodules were absent. The scanning confocal laser microscope (SCLM) images of three-week samples showed high bacterial activity around areas where manganese micro-nodules were starting to form on the pipe surface.

Slow Crack Growth Resistance of Parent and Joint Materials From PE4710 Piping for Safety-Related Nuclear Power Plant Piping

2011 ◽  
Author(s):  
S. Kalyanam ◽  
D.-J. Shim ◽  
P. Krishnaswamy ◽  
Y. Hioe
Keyword(s):  
Crack Growth ◽  
Nuclear Power ◽  
Power Plants ◽  
Slow Crack Growth ◽  
Nuclear Industry ◽  
Pipe Material ◽  
Service Water ◽  
Hdpe Pipe ◽  
Pipe Materials ◽  
Hdpe Pipes

HDPE pipes are considered by the nuclear industry as a potential replacement option to currently employed metallic piping for service-water applications. The pipes operate under high temperatures and pressures. Hence HDPE pipes are being evaluated from perspective of design, operation, and service life requirements before routine installation in nuclear power plants. Various articles of the ASME Code Case N-755 consider the different aspects related to material performance, design, fabrication, and examination of HDPE materials. Amongst them, the material resistance (part of Article 2000) to the slow crack growth (SCG) from flaws/cracks present in HDPE pipe materials is an important concern. Experimental investigations have revealed that there is a marked difference (almost three orders less) in the time to failure when the notch/flaw is in the butt-fusion joint, as opposed to when the notch/flaw is located in the parent HDPE material. As part of ongoing studies, the material resistance to SCG was investigated earlier for unimodal materials. The current study investigated the SCG in parent and butt-fusion joint materials of bimodal HDPE (PE4710) pipe materials acquired from two different manufacturers. The various stages of the specimen deformation and failure during the creep test are characterized. Detailed photographs of the specimen side-surface were used to monitor the specimen damage accumulation and SCG. The SCG was tested using a large specimen (large creep frame) as well as using a smaller size specimen (PENT frame) and the results were compared. Further, the effect of polymer orientation or microstructure in the bimodal HDPE pipe on the SCG was studied using specimens with axial and circumferential notch orientations in the parent pipe material.

Corrosion analysis of G105 coating drill-pipe washout

2014 ◽  
Vol 61 (6) ◽  
pp. 365-369 ◽  
Author(s):  
Zhouyang Lian ◽  
Dongsheng Chen ◽  
Wuji Wei ◽  
Yongzhang Zhou ◽  
Juncheng Jiang
Keyword(s):  
Design Methodology ◽  
Drill Pipe ◽  
Corrosion Process ◽  
Pipe Surface ◽  
Content Type ◽  
Pit Nucleation ◽  
Drill Pipes ◽  
Microstructure Of The Material ◽  
Pipe Materials ◽  
Selection Of

Purpose – The purpose of this study was to investigate the reason of G105 coated drill-pipes suffering from washout after drilling for 70000–80000 m. Design/methodology/approach – The microstructure, micromorphology and corrosion products near the washout were analyzed by metallurgical microscopy, SEM and EDS. Findings – Results showed the metallographic microstructure of the material was typical tempered sorbite. No fatigue crack was observed. Drill-pipe washout was caused mainly by the inclusion of MnS in steel because of the excess S and by damaged coating, both of which induced pit nucleation and promoted the pitting corrosion process. The corrosion hole extended from the interior to the exterior, which resulted in the fracturing of the external drill-pipe surface under pressure. Originality/value – This paper can give practical help to the selection of drill pipe materials in the future.

scholarly journals Modelling of butylated hydroxytoluene (BHT) transport in water in PE-HD pipe including chemical reaction of BHT oxidation

2018 ◽  
Vol 44 ◽  
pp. 00118
Author(s):  
Anna Musz-Pomorska ◽  
Beata Kowalska ◽  
Marcin K. Widomski
Keyword(s):  
Input Data ◽  
Calculated Data ◽  
Butylated Hydroxytoluene ◽  
Pipe Material ◽  
Laboratory Measurements ◽  
Different Types ◽  
Laminar And Turbulent Flow ◽  
Modelling Studies ◽  
Acceptable Agreement ◽  
Pipe Materials

This paper presents laboratory and modelling studies of antioxidant butylated hydroxytoluene leaching from a water supply PE-HD pipe for laminar and turbulent flow. The reaction of BHT oxidation to BHT-OH was included in our calculations. Required input data, initial and boundary conditions were based on laboratory measurements performed for a new PE-HD pipe. Laboratory measurements covered tests of BHT content and homogeneity in pipe material as well as measurements of BHT concentration in water flowing inside the pipe loop with different velocities. The BHT content of the PE-HD pipe and its concentration in water were determined by GC-MS method. Modelling calculations of BHT concentration in water for two different types of flow were performed using the commercial CDF software Fluent (Ansys Inc.). Non-homogeneous BHT distribution in pipe material and leaching of the antioxidant to the water were observed during laboratory tests. Numerical prediction of BHT concentration in water showed acceptable agreement between measured and calculated data. Nonetheless, the universality of the developed model is limited by the great diversity of available plastic pipe materials with various contents and technological amendments.

scholarly journals An evolutionarily diverged mitochondrial protein controls biofilm growth and virulence in Candida albicans

2020 ◽  
Author(s):  
Zeinab Mamouei ◽  
Shakti Singh ◽  
Bernard Lemire ◽  
Yiyou Gu ◽  
Abdullah Alqarihi ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Amino Acid ◽  
Mitochondrial Protein ◽  
Carbon Sources ◽  
Three Dimensional ◽  
Antifungal Drugs ◽  
Biofilm Growth ◽  
Biochemical Assays ◽  
Transport Chain ◽  
Biofilm Detachment

AbstractA forward genetic screening approach identified orf19.2500, as a gene controlling Candida albicans biofilm dispersal and biofilm detachment. Three-dimensional (3-D) protein modeling and bioinformatics revealed that orf19.2500 is a conserved mitochondrial protein, structurally similar to, but functionally diverged from, the squalene/phytoene synthases family. The C. albicans orf19.2500 is distinguished by three evolutionarily acquired stretches of amino acid inserts, absent from all other eukaryotes except a small number of ascomycete fungi. Biochemical assays showed that orf19.2500 is required for the assembly and activity of the NADH ubiquinone oxidoreductase Complex I of the respiratory electron transport chain, and was thereby named NDU1. NDU1 is essential for respiration and growth on alternative carbon sources, important for immune evasion, required for virulence in a mouse model of hematogenously disseminated candidiasis, and for potentiating resistance to antifungal drugs. Our study is the first report on a protein that sets the Candida-like fungi phylogenetically apart from all other eukaryotes, based solely on evolutionary “gain” of new amino acid inserts that are also the functional hub of the protein.

Brittle fracture in PVC pipe material

2007 ◽  
Vol 72 (1) ◽  
pp. 83-110 ◽  
Author(s):  
Frederick J. McGarry ◽  
John F. Mandell ◽  
Lidia Hsueh-Lee
Keyword(s):  
Brittle Fracture ◽  
Pipe Material ◽  
Pvc Pipe

Multi-stage assessment of biofilm growth by drinking water bacteria on polymeric pipe materials

2020 ◽  
Author(s):  
Olga Sójka ◽  
Patrick van Rijn ◽  
Henny van der Mei ◽  
Maria Cristina Gagliano
Keyword(s):  
Drinking Water ◽  
Biofilm Formation ◽  
Distribution Systems ◽  
Pipe Material ◽  
Bacterial Strains ◽  
Drinking Water Contamination ◽  
Multi Stage ◽  
Biofilm Development ◽  
Pipe Materials ◽  
Mechanical Cleaning

<p><strong>Introduction</strong></p> <p>The presence of biofilms in drinking water distribution systems (DWDS) leads to a number of issues, i.e. secondary (biological) drinking water contamination, pipe damage and increased flow resistance. Among other operational factors, the selection of pipe material plays an important role in biofilm development. Up to now, the studies that have investigated this correlation provide contradictory results in terms of which material might be the most advantageous in the DWDS biofilm control strategy. Hence, to understand the influence of pipe material on biofilm formation, we focused on developing a standardized methodology that allows a multi-stage assessment of biofilm development on real pipe materials.</p> <p><strong>Results</strong></p> <p>Development of the methodology consisted of three steps: 1) material coupon sterilization, 2) biofilm cultivation and 3) biofilm analysis, using  transparent polyvinyl chloride (PVC) as a study material. For the coupon sterilization, methods utilizing immersion in different disinfectant solutions with and without pre-cleaning by rubbing the coupons in a surfactant solution. The results showed that mechanical cleaning before washing  is crucial and without it, reproducible sterilization was difficult to achieve. Biofilm formation on the PVC coupons was performed in a 6-well plate assay (24, 48 and 72 h; under agitation) using DWDS biofilm strains (<em>Sphingomonas spp</em>. and <em>Pseudomonas extremorientalis</em>) and <em>Pseudomonas aeruginosa</em> as a positive control. Bacterial fitness and ability to secrete EPS and form biofilms on the PVC surfaces were tested by monitoring optical density (OD600 nm), chemical oxygen demand (COD) and protein concentration. The formed biofilm and the morphology of attached bacteria were visualized using crystal violet staining (that allow qualitative (bright field microscopy) and quantitative (OD at 570 nm) evaluation), by scanning electron microscopy (SEM) and DNA staining (4′,6-diamidino-2-phenylindole; DAPI) with fluorescence microscopy. Combination of those techniques gave a complete overview of patterns involved in biofilm development by selected drinking water bacterial strains in presence of a PVC surface. The developed methodology was also applied  for the analysis of bacterial growth on real-grade pipe materials, such as PVC and polyethylene (PE), to understand their role in biofilm formation.</p> <p><strong>Conclusions</strong></p> <p>Implementation of various analytical and microscopic techniques is important in understanding mechanisms behind biofilm development in DWDS and the influence of pipe material in the process. The proposed approach allows the observation of biofilm formation in time, but also of the typical bacterial morphology of attached cells. In this study it was shown that to obtain reproducible results, it is crucial to select an appropriate sterilization technique and the influence of mechanical cleaning cannot be ignored in preparation of polymeric surfaces.</p>

Biofilm development in fixed bed biofilm reactors: experiments and simple models for engineering design purposes

2013 ◽  
Vol 68 (6) ◽  
pp. 1391-1399 ◽  
Author(s):  
N. Szilágyi ◽  
R. Kovács ◽  
I. Kenyeres ◽  
Zs. Csikor
Keyword(s):  
Experimental Data ◽  
Time Constant ◽  
Process Design ◽  
Fixed Bed ◽  
Engineering Practice ◽  
Hydrodynamic Conditions ◽  
Data Set ◽  
Biofilm Growth ◽  
State Process ◽  
Biofilm Development

Biofilm development in a fixed bed biofilm reactor system performing municipal wastewater treatment was monitored aiming at accumulating colonization and maximum biofilm mass data usable in engineering practice for process design purposes. Initially a 6 month experimental period was selected for investigations where the biofilm formation and the performance of the reactors were monitored. The results were analyzed by two methods: for simple, steady-state process design purposes the maximum biofilm mass on carriers versus influent load and a time constant of the biofilm growth were determined, whereas for design approaches using dynamic models a simple biofilm mass prediction model including attachment and detachment mechanisms was selected and fitted to the experimental data. According to a detailed statistical analysis, the collected data have not allowed us to determine both the time constant of biofilm growth and the maximum biofilm mass on carriers at the same time. The observed maximum biofilm mass could be determined with a reasonable error and ranged between 438 gTS/m2 carrier surface and 843 gTS/m2, depending on influent load, and hydrodynamic conditions. The parallel analysis of the attachment–detachment model showed that the experimental data set allowed us to determine the attachment rate coefficient which was in the range of 0.05–0.4 m d−1 depending on influent load and hydrodynamic conditions.

Effectiveness of Hydrostatic Testing for High Strength Pipe Material

2010 ◽  
Author(s):  
Kimberly Cameron ◽  
Alfred M. Pettinger
Keyword(s):  
Stress State ◽  
Crack Growth ◽  
High Strength ◽  
Pipe Material ◽  
Test Pressure ◽  
Safe Control ◽  
Low Probability ◽  
Lower Test ◽  
Crack Growth Rates ◽  
Pipe Materials

Pipeline systems are typically subjected to hydrostatic testing to help ensure pipeline integrity. It can be desirable to use the highest feasible test pressure to eliminate as many defects as possible. It is widely accepted that safe control of yielding can be achieved during hydrostatic testing and that the hydrostatic testing does not create a stress state that is less safe from the standpoint of pre-existing flaws. For a small percentage of cases, however, hydrostatic testing can produce flaws that were longer than the ones removed. In these few cases, the flaws can then fail at a lower test pressure than the original hydrostatic test. The low probability of these events, however, means that the effectiveness of the hydrostatic test is not significantly diminished in this case. Because crack growth from a pre-existing flaw is retarded in a plastically deformed material, it is also typically assumed that hydrostatic testing should not lead to accelerated crack growth. However, this does not take into account that the hydrostatic testing itself can cause some increment in crack growth and that for many higher strength pipe materials significantly large defects can survive hydrostatic testing. These longer defects can potentially grow after surviving a hydrostatic test. This paper discusses this difference in crack growth rates for cracks that have survived hydrostatic testing in different grade pipeline steels and the implications for hydrostatic testing.

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