Coating Life Prediction for Water Ballast Tank

2005 ◽  
Author(s):  
R. E. Melchers ◽  
X. L. Jiang ◽  
K. J. Lu
Keyword(s):  
Life Prediction ◽  
Practical Implication ◽  
Plate Thickness ◽  
Surface Preparation ◽  
Ballast Tank ◽  
Independent Expert ◽  
Key Factor ◽  
Ballast Tanks ◽  
Dry Film Thickness ◽  
Insight Into

Corrosion is the key factor responsible for the degradation of ship structures and in no place is this truer than water ballast tanks. Coating protection system is a continual research interest for classification societies and coating industries. Up to now, most coating performance analyses are qualitative not quantitative. Coating life prediction is almost always based on experience and various assumptions, due to unavailability of practical data support systems. This paper describes a preliminary impartial investigation of coating life carried out with interviewees from the Australian Defence Science and Technology Organization (DSTO), shipyards, coating supplier and an independent expert. Plate surface, edges and welds in ballast tank were considered and the influences of dry film thickness (DFT) and surface preparation (SP) are addressed. The investigation gives some insight into the life of practical coating systems for water ballast tanks. Coating life is proposed to be representable by a normal distribution when corrosion breakdown is below 10% of plate thickness, which is of practical implication.

A Study into the Coating Thickness of Ship Ballast Tanks

2020 ◽  
Vol 162 (A3) ◽  
Author(s):  
B Khan ◽  
F Khan ◽  
B Veitch
Keyword(s):  
Coating Thickness ◽  
Performance Standard ◽  
Coating System ◽  
Ballast Tank ◽  
Coating Performance ◽  
Coating Application ◽  
Flat Surfaces ◽  
Ballast Tanks ◽  
Dry Film Thickness

Ballast tanks are expected to be coated according to the IMO Performance Standard for Protective Coating regulations (PSPC15), in addition to the paint application requirements of the paint producer. In general, a coating system should consist of minimum two spray coats of light-colored epoxy coating on flat surfaces with a Nominal total Dry Film Thickness (NDFT) of 320 μm and 90% of all thickness measurements greater than, or equal to the NDFT and none of the remaining measurements below 0.9 x NDFT (the “90/10 rule”). Allegedly, the value of 320 μm in this PSPC15 rule may be misconstrued as a benchmark for coating application on flat surfaces, eventually leading to a non-PSPC15 compliance due to the resulting variation in coating thickness violating this 90/10 rule. This study indicates that over the years, the arithmetic mean in-situ DFT appears to be 498±18 μm and that too high and low thicknesses, below 288 μm and above 800 μm, were noted in the field. Analysis of a survey of ballast tank coating performance of ships indicates that too low thicknesses appear to be negatively impacting the average theoretical ballast tank performance. However, when an application mean DFT benchmark of 525 μm is used, the coating will almost surely comply to the 90/10 rule and the risk of falling below the 288 μm threshold is small, less than 2% in most cases. Consequently, using 320 μm as a mean DFT benchmark could result in a non-PSPC15 compliance with the in-situ ascertained coating thickness variation as this does not exclude coating thicknesses below 288 μm, which may then result in a significantly less than average theoretical coating performance. If the coating application is performed very evenly, the benchmark may be reduced to 429 μm with a probability of falling below 288 μm reduced to 0.1%. It should therefore be emphasized that the PSPC15 requirement is a coating system framework description, and that the requirement should be broadened to include a mean DFT as a coating applicator benchmark together with a clearly specified minimum and maximum DFT, in order to avoid any misinterpretations.

Taking Care of Ballast Tank Coatings = Green Ballast Tanks Coatings

2014 ◽  
Author(s):  
Kris De Baere ◽  
Helen Verstraelen ◽  
Remke Willemen ◽  
Raf Meskens ◽  
Geert Potters
Keyword(s):  
Environmental Impact ◽  
Complex Structure ◽  
Regression Line ◽  
Age Distribution ◽  
Surface Preparation ◽  
Surface Cleaning ◽  
Ballast Tank ◽  
Coating Application ◽  
Significant Difference ◽  
Ballast Tanks

Shipping plays an important role in the logistic chain. These a worthiness of ships transporting goods world wide is therefore crucial. One element defining these a worthiness of a ship is the condition of her ballast tanks. These tanks are an area of concern for ship owners and crew. They are subject to corrosion; and due to the enclosed environment and complex structure, maintenance is very difficult and costly. This paper gives the results of an “insitu” study of ballast tanks on board of more than 150 merchant ships. No selection criteria were applied from the start and the ships were surveyed as opportunity arose. Most of the ships are worldwide trading and the age varies between brand new and 36years. Figure 1 gives a good idea of the age distribution. Many types of ships are represented in the database amongst others 10oil tankers, 14 liquefied gas carrier, 25 chemical tankers, 28 bulk carriers, 23 full containers carriers, 5 general cargoes, 9 RoRo’s, 8 refrigerated ships. Surface corrosion was assessed, compared and the importance of condition and environmental parameters during coating application recognized. The paper also reveals the significant difference between the average corrosion regression line of the data base and the coating condition in the ballast tanks on board ships to where the operator invested in a superior coating system at new building, with extra attention to surface preparation and coating application. The need to reduce the environmental impact of shipping becomes more and more obvious. Blasting with shot and grit, vast amounts of water used for water jetting and rinsing, surface cleaning and high solvent coatings jeopardize our future generations. Luckily, there duction of the environmental impact has beneficial economic consequences a sit brings down significantly maintenance costs.

A STUDY INTO THE COATING THICKNESS OF SHIP BALLAST TANKS

2021 ◽  
Vol 162 (A3) ◽  
Author(s):  
R Willemen ◽  
D Luyckx ◽  
R Meskens ◽  
S Lenaerts ◽  
K De Baere
Keyword(s):  
Coating Thickness ◽  
Performance Standard ◽  
Coating System ◽  
Ballast Tank ◽  
Coating Performance ◽  
Coating Application ◽  
Flat Surfaces ◽  
Ballast Tanks ◽  
Dry Film Thickness

Ballast tanks are expected to be coated according to the IMO Performance Standard for Protective Coating regulations (PSPC15), in addition to the paint application requirements of the paint producer. In general, a coating system should consist of minimum two spray coats of light-colored epoxy coating on flat surfaces with a Nominal total Dry Film Thickness (NDFT) of 320 μm and 90% of all thickness measurements greater than, or equal to the NDFT and none of the remaining measurements below 0.9 x NDFT (the “90/10 rule”). Allegedly, the value of 320 μm in this PSPC15 rule may be misconstrued as a benchmark for coating application on flat surfaces, eventually leading to a non-PSPC15 compliance due to the resulting variation in coating thickness violating this 90/10 rule. This study indicates that over the years, the arithmetic mean in-situ DFT appears to be 498±18 μm and that too high and low thicknesses, below 288 μm and above 800 μm, were noted in the field. Analysis of a survey of ballast tank coating performance of ships indicates that too low thicknesses appear to be negatively impacting the average theoretical ballast tank performance. However, when an application mean DFT benchmark of 525 μm is used, the coating will almost surely comply to the 90/10 rule and the risk of falling below the 288 μm threshold is small, less than 2% in most cases. Consequently, using 320 μm as a mean DFT benchmark could result in a non-PSPC15 compliance with the in-situ ascertained coating thickness variation as this does not exclude coating thicknesses below 288 μm, which may then result in a significantly less than average theoretical coating performance. If the coating application is performed very evenly, the benchmark may be reduced to 429 μm with a probability of falling below 288 μm reduced to 0.1%. It should therefore be emphasized that the PSPC15 requirement is a coating system framework description, and that the requirement should be broadened to include a mean DFT as a coating applicator benchmark together with a clearly specified minimum and maximum DFT, in order to avoid any misinterpretations.

Stability of H-terminated BDD electrodes: an insight into the influence of the surface preparation

2007 ◽  
Vol 204 (9) ◽  
pp. 2931-2939 ◽  
Author(s):  
E. Vanhove ◽  
J. de Sanoit ◽  
J. C. Arnault ◽  
S. Saada ◽  
C. Mer ◽  
...  
Keyword(s):  
Surface Preparation ◽  
Insight Into

scholarly journals Reliability of Neural Implants—Effective Method for Cleaning and Surface Preparation of Ceramics

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 209
Author(s):  
Patrick Kiele ◽  
Jan Hergesell ◽  
Melanie Bühler ◽  
Tim Boretius ◽  
Gregg Suaning ◽  
...  
Keyword(s):  
Surface Preparation ◽  
Neural Implants ◽  
Implantable Medical Devices ◽  
Welding Flux ◽  
Extensive Evaluation ◽  
Surface Analysis Techniques ◽  
Key Factor ◽  
Ceramic Components ◽  
University College London ◽  
Cleaning Procedures

Neural implants provide effective treatment and diagnosis options for diseases where pharmaceutical therapies are missing or ineffective. These active implantable medical devices (AIMDs) are designed to remain implanted and functional over decades. A key factor for achieving reliability and longevity are cleaning procedures used during manufacturing to prevent failures associated with contaminations. The Implantable Devices Group (IDG) at University College London (UCL) pioneered an approach which involved a cocktail of reagents described as “Leslie’s soup”. This process proved to be successful but no extensive evaluation of this method and the cocktail’s ingredients have been reported so far. Our study addressed this gap by a comprehensive analysis of the efficacy of this cleaning method. Surface analysis techniques complemented adhesion strengths methods to identify residues of contaminants like welding flux, solder residues or grease during typical assembly processes. Quantitative data prove the suitability of “Leslie’s soup” for cleaning of ceramic components during active implant assembly when residual ionic contaminations were removed by further treatment with isopropanol and deionised water. Solder and flux contaminations were removed without further mechanical cleaning. The adhesive strength of screen-printed metalisation layers increased from 12.50 ± 3.83 MPa without initial cleaning to 21.71 ± 1.85 MPa. We conclude that cleaning procedures during manufacturing of AIMDs, especially the understanding of applicability and limitations, is of central importance for their reliable and longevity.

scholarly journals Effect of Cover Plate on the Ballistic Performance of Ceramic Armor

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Miao Sun ◽  
Wuxiong Cao ◽  
Diqi Hu ◽  
Nana Zhang ◽  
Runqiang Chi
Keyword(s):  
Plate Thickness ◽  
Cover Plate ◽  
Ballistic Performance ◽  
Transition Velocity ◽  
Free Mode ◽  
Long Rod ◽  
Lower Limits ◽  
Insight Into ◽  
Velocity Region ◽  
Cover Plates

The interface defeat and dwell can effectively improve the ballistic performance of ceramic armors under high velocity impact of long rod projectiles. Confinement conditions along both axial and radial directions of ceramic armors can affect these behaviors. With the aim of giving an insight into the effect of cover plate thickness and connection mode of cover plates with confining tubes on these behaviors, numerical simulations were performed in which the confined silicon carbide (SiC) targets with cover plates were impacted by tungsten rods. The pressure on the surfaces of SiC targets with fixed cover plates are compared to that with free cover plates, showing that the plates fixed with the confining tubes can produce higher pressure by way of wedging. With the increase in cover plate thickness, the dwell duration of the tungsten rods on the ceramic interface gradually grows. In addition, the upper and lower limits of transition impact velocities for the SiC targets with cover plates in different connection modes (i.e., free or fixed) were obtained and analyzed. The results show that the increase rate of the transition velocity region for the cover plate with the fixed-mode is relatively stable and lower than with the free-mode. On this basis, the fixed cover plate contributes higher ballistic performances to the SiC target than the free cover plate. It is also noteworthy that the size of transition velocity region does not enlarge linearly with the increase in cover plate thickness due to the slow growth of the upper limit. Accordingly, thickness thresholds exist, which are 5 mm and 6 mm for the fixed and free cover plates, respectively. Considering the ballistic performance and economy, the cover plate with the thickness ranging from 3 mm to 5 mm, i.e., 1.5~2.5 times of the tungsten rod diameter, is ideal for the structural dimensions in this paper.

What determines a boundary for navigating a complex street network: evidence from London taxi drivers

2021 ◽  
pp. 1-20
Author(s):  
Eva-Maria Griesbauer ◽  
Ed Manley ◽  
Daniel McNamee ◽  
Jeremy Morley ◽  
Hugo Spiers
Keyword(s):  
Urban Space ◽  
Large Scale ◽  
Route Planning ◽  
Taxi Drivers ◽  
Street Networks ◽  
Planning Models ◽  
Key Factor ◽  
Efficient Planning ◽  
Regent's Park ◽  
Insight Into

Abstract Spatial boundaries play an important role in defining spaces, structuring memory and supporting planning during navigation. Recent models of hierarchical route planning use boundaries to plan efficiently first across regions and then within regions. However, it remains unclear which structures (e.g. parks, rivers, major streets, etc.) will form salient boundaries in real-world cities. This study tested licensed London taxi drivers, who are unique in their ability to navigate London flexibly without physical navigation aids. They were asked to indicate streets they considered as boundaries for London districts or dividing areas. It was found that agreement on boundary streets varied considerably, from some boundaries providing almost no consensus to some boundaries consistently noted as boundaries. Examining the properties of the streets revealed that a key factor in the consistent boundaries was the near rectilinear nature of the designated region (e.g. Mayfair and Soho) and the distinctiveness of parks (e.g. Regent's Park). Surprisingly, the River Thames was not consistently considered as a boundary. These findings provide insight into types of environmental features that lead to the perception of explicit boundaries in large-scale urban space. Because route planning models assume that boundaries are used to segregate the space for efficient planning, these results help make predictions of the likely planning demands of different routes in such complex large-scale street networks. Such predictions could be used to highlight information used for navigation guidance applications to enable more efficient hierarchical planning and learning of large-scale environments.

scholarly journals The Effects of Manifest Residual Variances, Indicator Communality, and Sample Size on the χ2-Test Statistic of the Metric Invariance Model

2019 ◽  
Author(s):  
Eric Klopp ◽  
Stefan Klößner
Keyword(s):  
Sample Size ◽  
Measurement Invariance ◽  
Signal To Noise Ratio ◽  
Practical Implication ◽  
Residual Variance ◽  
Test Statistic ◽  
Monte Carlo Studies ◽  
Key Factor ◽  
Metric Measurement ◽  
Invariance Model

In this contribution, we investigate the effects of manifest residual variance, indicator communality and sample size on the χ2-test statistic of the metric measurement invariance model, i.e. the model with equality constraints on all loadings. We demonstrate by means of Monte Carlo studies that the χ2-test statistic relates inversely to manifest residual variance, whereas sample size and χ2-test statistic show the well-known pro- portional relation. Moreover, we consider indicator communality as a key factor for the size of the χ2-test statistic. In this context, we introduce the concept of signal-to-noise ratio as a tool for studying the effects of manifest residual error and indicator commu- nality and demonstrate its use with some examples. Finally, we discuss the limitations of this contribution and its practical implication for the analysis of metric measurement invariance models.

scholarly journals Recent Insight into SARS-CoV2 Immunopathology and Rationale for Potential Treatment and Preventive Strategies in COVID-19

Vaccines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 224 ◽  
Author(s):  
Sara Lega ◽  
Samuele Naviglio ◽  
Stefano Volpi ◽  
Alberto Tommasini
Keyword(s):  
Severe Disease ◽  
Host Immune System ◽  
Great Effort ◽  
Clinical Observations ◽  
Current State ◽  
Key Factor ◽  
Pharmacologic Treatments ◽  
Immunomodulating Drugs ◽  
Insight Into

As the outbreak of the new coronavirus (SARS-CoV-2) infection is spreading globally, great effort is being made to understand the disease pathogenesis and host factors that predispose to disease progression in an attempt to find a window of opportunity for intervention. In addition to the direct cytopathic effect of the virus, the host hyper-inflammatory response has emerged as a key factor in determining disease severity and mortality. Accumulating clinical observations raised hypotheses to explain why some patients develop more severe disease while others only manifest mild or no symptoms. So far, Covid-19 management remains mainly supportive. However, many researches are underway to clarify the role of antiviral and immunomodulating drugs in changing morbidity and mortality in patients who become severely ill. This review summarizes the current state of knowledge on the interaction between SARS-CoV-2 and the host immune system and discusses recent findings on proposed pharmacologic treatments.

Numerical Simulation of Sloshing of Water in Ship Tanks During Sequential Ballast Water Exchange in Seaways

2002 ◽  
Author(s):  
Makoto Arai ◽  
Humberto S. Makiyama ◽  
Liang-Yee Cheng
Keyword(s):  
Ballast Water ◽  
Water Exchange ◽  
Sea Water ◽  
Marine Pollution ◽  
Aquatic Organisms ◽  
Exchange Method ◽  
Ballast Tank ◽  
Open Sea ◽  
Merchant Ship ◽  
Ballast Tanks

In recent years, ballast water has been blamed for a variety of marine pollution problems, particularly for transporting harmful aquatic organisms from one part of the world to another and damaging the ecosystem of the new areas. A relatively simple mechanism to control this problem is to exchange ballast water on the high seas between ports in order to remove invasive species before the ship reaches its destination. However, some issues regarding ballast exchange on the open sea need to be addressed before this operation is introduced. One of them is the sloshing of the sea water in the ballast tank. In this paper, ballast water exchange on the open sea by means of the Sequential exchange method is simulated. Irregular seaways are generated from the ISSC spectrum, and the sloshing response of the water in the ballast tanks of a large merchant ship is numerically computed by using a finite difference code developed by the authors. The results showed that there is little possibility that severe sloshing presents a serious problem in regard to the ballast tank’s strength, especially in the case of a bulk carrier whose tanks are generally short in length, with sloshing anticipated only at the low water level.

Sign in / Sign up

Export Citation Format

Share Document