Designing of a single pack wash primer for aluminium surfaces in a marine environment

Design aspects and comparative performances of different laboratory formulations of wash primers were studied under laboratory and field conditions with reference to scratch hardness, flexibility, stability, resistance to corrosion and adhesiveness. The different formulations of single pack wash primers tested have shown superiority of the formulation prepared out of “mowital” and that it is comparable in performance to double pack wash primer.

Experimental formulation of an anti fouling paint with tributyl tin oxide as toxic pigment

Results of the experimental formulation of an antifouling paint incorporating TBTO as toxic pigment are presented in this paper. Of the various resins tested, namely, phenolic, cashew nut shell liquid (CNSL), epoxy linseed oil with rosin and limed rosin, the paint composition with limed rosin gave the critical leaching rate of TBTO. Acid alkali test showed dissolution of matrix and visible migration of toxin to the surface. Accelerated corrosion tests had not recorded any signs of corrosion in panels painted with or without barrier coat. Raft exposure studies indicated that the new formulation could resist fouling accumulation on painted panels for 9 months.

Cathodic protection of the hulls of fishing trawlers in India

Nearly 10,000 mechanised fishing trawlers mostly built of wood and about 100 trawlers built of steel besides a few fiberglass reinforced plastic and a couple of ferro-cement boats constitute the modern fishing fleet of India at present. Metallic corrosion in sea water is a very well-known phenomenon in all ships and various other marine structures; the exact financial loss and the material breakdowns have never been fully realized among the trawler owners in India. The Central Institute of Fisheries Technology at Cochin has been studying these problems for some years and has been able to assess the significance of underwater corrosion particularly of the hull below water line in the trawlers and suitable remedial measures have been suggested in this paper.

Copper-nickel alloys for marine aquacultural engineering

Engineering developments, problems of marine corrosion, fouling and practical innovative applications of copper-nickel alloys in comparison with other materials for marine aquacultural engineering are presented. Coefficient of drag and hydrodynamic force acting on nylon and polyethylene net enclosures have shown a four-fold increase of force in four months at the Cochin harbour due to fouling. Corrosion behaviour of copper-nickel and other copper base alloys are also presented. Effects of copper additions to culture water are reviewed.

Development of canned fish curry

A process for canning sardine in two different curry media is presented. One curry medium yields a product with medium pungency while the second one has a low pungency. Sardine canned in curry medium having medium pungency developed signs of internal corrosion as well as slight bitter taste at the end of 15 months storage at ambient temperature. Similar phenomenon took place in the other product only at the end of 18 months storage. Being a ready to serve product it needs no further preparation for the table.

Effect of sulphide on Admiralty brass in seawater

The corrosion behaviour of Admiralty brass in putrified seawater has been studied. It was observed that when the dissolved oxygen in the putrified seawater medium has attained very low value (<0.53 p.p.m) the corrosion rate of admiralty brass showed decreasing trend in spite of increased level of sulphide from 21.2 to 228 p.p.m. Significant correlations (negative) were observed between corrosion rates and log period of exposure.

Increasing the life of flare tips

Flare tips are essential for safety. Maintenance is difficult and costly. Flare tips are subjected to high combustion temperatures, thermal cycling, oxidation and marine corrosion. Following a number of flare tip failures an in depth study by Imperial College was carried out into the failure of a flare tip from a UK platform, looking for service life improvement. Materials selection and design solutions were considered. The study considered alternative materials and concluded that materials selection was the smaller part of the answer; design changes can double service life. This study used failure investigation, high temperature experimental and thermo-mechanical modelling analysis. The modelling process simulated two common flaring conditions and correctly predicted the observed failure of initiation and crack propagation from holes used to bolt on flame stabilizing plates to the top of the flare. The calculated thermal stress and strains enabled the low cycle fatigue life and minimum creep life to be predicted. It was concluded that service life could be improved by replacing Incoloy alloy 800HT (UNS N08800) with Inconel alloy 625 (UNS N06625), an alloy with attractive mechanical properties and improved high temperature corrosion resistance. Repositioning or eliminating bolt holes can double service life. Copyright 2008, Society of Petroleum Engineers.

Powder stream characteristics in cold spray nozzles

The exponential increase of industrial demand in the past two decades has led scientists to the development of alternative technologies for the fast manufacturing of engineering components, aside from standard and time consuming techniques such as casting or forging.Cold Spray (CS) is a newly developed manufacturing technique, based upon the deposition of metal powder on a substrate due to high energy particle impacts. In this process, the powder is accelerated up to considerable speed in a converging-diverging nozzle, typically using air, nitrogen or helium as a carrier gas. Recent developments have demonstrated significant process capabilities, from the building of mold-free 3D shapes made of various metals, to low porosity and corrosion resistant titanium coatings.In CS, the particle stream characteristics during the acceleration process are important in relation to the final geometry of the coating. Experimental studies have shown the tendency of particles to spread over the nozzle acceleration channel, resulting in a wide exit stream and in the difficulty of producing narrow tracks.This paper presents an investigation on the powder stream characteristics in CS supersonic nozzles. The powder insertion location was varied within the carrier gas flow, along with the geometry of the powder injector, in order to identify their relation with particle trajectories. Computational Fluid Dynamics (CFD) results by Fluent v6.3.26 are presented, along with experimental observations. Different configurations were tested and modeled, giving deposited track geometries of copper and tin ranging from 1. mm to 8. mm in width on metal and polymer substrates. © 2011 Elsevier B.V.

Flaw sizing in pipes using long-range guided wave testing

The absence of adequate inspection data from difficult-to-access areas on pipelines, such as cased-road crossings, makes determination of fitness for continued service and compliance with increasingly stringent regulatory requirements problematic. Screening for corrosion using long-range guided wave testing is a relatively new inspection technique. The complexity of the possible modes of vibration means the technique can be difficult to implement effectively but this also means that it has great potential for both detecting and characterizing flaws. The ability to determine flaw size would enable the direct application of standard procedures for determining fitness-for-service, such as ASME B31G, RSTRENG, or equivalent for tens of metres of pipeline from a single inspection location. This paper presents a new technique for flaw sizing using guided wave inspection data. The technique has been developed using finite element models and experimentally validated on 6'' Schedule 40 steel pipe. Some basic fitness-for-service assessments have been carried out using the measured values and the maximum allowable operating pressure was accurately determined. © 2011 American Institute of Physics.

Analysis and retrofitting design of a single-span R.C. bridge

This paper deals with the case history of a damaged one-span prestressed concrete bridge on a crucial artery near the city of Cagliari (Sardinia), along the sea-side. After being involved in a disastrous flood, attention has arisen on the worrying safety state of the deck, submitted to an intense daily traffic load. Evident signs of this severe condition were the deterioration of the beams concrete and the corrosion, the lack of tension and even the rupture of the prestressing cables. After performing a limited in situ test campaign, consisting of sclerometer, pull out and carbonation depth tests, a first evaluation of the safety of the structure was performed. After collecting the data of dynamic and static load tests as well, a comprehensive analysis have been carried out, also by means of a properly calibrated F.E. model. Finally the retrofitting design is presented, consisting of the reparation and thickening of the concrete cover, providing flexural and shear FRP external reinforcements and an external prestressing system, capable of restoring a satisfactory bearing capacity, according to the current national codes. The intervention has been calibrated by the former F.E. model with respect to transversal effects and influence of local and overall deformation of reinforced elements. © 2012 Taylor & Francis Group.

采油污水回注系统缓蚀阻垢技术研究

油田腐蚀与结垢是油田生产面临的普遍问题。随着油田开发时间的延长，注水开采成为普遍采用的采油工艺。因此，腐蚀与结垢问题十分突出。腐蚀和结垢现象的存在，增大了油田生产成本，给开发生产造成惨重的经济损失，是制约油田高效益、低投入快速发展的关键因素之一。 本文以辽河油田采油污水为研究对象。在水质特征和垢样组成分析的基础上，明确了腐蚀结垢原因。以六偏磷酸钠（(NaPO3)6）和硫酸锌（ZnSO4•7H2 O）为缓蚀剂，以氨基三亚甲基膦酸（ATMP）和羟基亚乙基二膦酸（HEDP）为阻垢剂，添加少量聚合物分散剂筛选复配出具有缓蚀、阻垢和分散等功能的高效复合缓蚀阻垢剂。研究了缓蚀剂含量、添加聚合物分散剂、药剂浓度、油田其他助剂等对缓蚀阻垢剂性能的影响，并探讨了药剂的缓蚀阻垢机制。 针对高升采油厂和沈阳采油厂的注水水质，筛选复配的缓蚀阻垢剂最佳配比及投加浓度为：(NaPO3)6，11.2mg/L； ZnSO4•7H2O，16.8mg/L；HEDP，7.2mg/L；ATMP，4.8mg/L；水解聚马来酸酐（HPMA）或丙烯酸/丙烯酸羟丙酯/AMPS共聚物（W-118A），5.0mg/L。总浓度为45mg/L。 室内动态模拟实验结果表明，复配缓蚀阻垢剂缓蚀率和阻垢率达99%以上，腐蚀速率低于0.02mm/a，具有优良的缓蚀阻垢性能。药剂性能评价结果表明该复合缓蚀阻垢剂具有耐高温、投加剂量低，与油田其他助剂配伍性好，低磷环保等优点。 现场试验和推广应用研究结果表明，筛选复配的缓蚀阻垢剂适合于辽河油田采油污水回注系统，腐蚀速率从以前的1.135mm/a降低到0.038mm/a，缓蚀率和阻垢率均达到96%以上，能够达到辽河油田采油污水回注系统防腐阻垢控制目标的要求，并且腐蚀速率也低于国家石油化工行业标准的防腐阻垢控制要求（≤0.075mm/a）。 通过经济效益分析表明，采用该项工艺技术经济效益显著，具有较好的推广应用前景。

一株高温硫酸盐还原菌的分离、鉴定及其对金属腐蚀研究

从四川化工总厂热交换器中分离到一株嗜热硫酸盐还原菌，该菌对金属有腐蚀作用。菌体形状呈微弯或直杆状，大小为0.5-0.8μm宽，2.8-4.3μm长，革兰氏阴性，周生鞭毛，运动，形成次端生的椭圆形芽孢，细胞内部构造丰富，菌落在不含Fe++盐的培养基上生长时，呈灰白色，直径为0.5mm，边缘不整齐，在含Fe++盐的培养基上生长时则为黑色，直径为2-3mm，菌落中央有0.5mm左右的小突起，该菌最适生长温度为50℃，最适PH6.5，不耐盐，可于沸水(99℃)中处理6小时而不失活，能利用H2＋CO2，乙醇，卜葡糖 ，可溶性淀粉，甲酸盐，乳酸盐，丙酮酸盐为唯一碳源，生长需要酵母膏，无脱硫弧菌素和细胞色素C3。

A mathematical model of crevice and pitting corrosion���I. The physical model

A predictive and self-consistent mathematical model incorporating the electrochemical, chemical and ionic migration processes characterizing the propagation stage of crevice and pitting corrosion in metals is described. The model predicts the steady-state solution chemistry and electrode kinetics (and hence metal penetration rates) within an active corrosion cavity as a function of the many parameters on which these depend, such as external electrode potential and crevice dimensions. The crevice is modelled as a parallel-sided slot filled with a dilute sodium chloride solution. The cavity propagation rates are found to be faster in the case of a crevice with passive walls than one with active walls. The distribution of current over the internal surface of a crevice with corroding walls can be assessed using this model, giving an indication of the future shape of the cavity. The model is extended to include a solid hydroxide precipitation reaction and considers the effect of consequent changes in the chemical and physical environment within the crevice on the predicted corrosion rates. In this paper, the model is applied to crevice and pitting corrosion in carbon steel.

Laser glazing of lanthanum magnesium hexaaluminate

Lanthanum magnesium hexaalumminate (LMA) is an important candidate for thermal barrier coatings due to its thermal stability and low thermal conductivity. On the other hand, laser glazing method can potentially make thermal barrier coatings impermeable, resistant to corrosion on the surface and porous at bulk. LMA powder was synthesized at 1600 degrees C by solid-state reaction, pressed into tablet and laser glazed with a 5-kW continuous wave CO2 laser.

Rare Earth Fluorides Nanowires/Nanorods Derived from Hydroxides: Hydrothermal Synthesis and Luminescence Properties

In this paper, we reported the synthesis of nearly monodisperse and well-defined one-dimensional (1D) rare earth fluoride(beta-NaREF4) (RE = Y, Sm, Eu, Gd, Tb, Dy, and Ho) nanowires/nanorods by in situ acid corrosion and anion exchange approach using RE(OH)(3) as precursors via a facile hydrothermal route. X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy. scanning electron microscopy (SEM), transmission electron microscopy (TEM). high-resolution transmission electron microscopy (HRTEM), and photoluminescence(PL)spectroscopy were used to characterize the samples. The results show that the as-prepared rare earth fluoride (beta-NaREF4) nanowires/nanorods preserve the basic morphology of the initial RE(OH)(3) precursors.