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This paper aims to establish the downhole CO₂ partial pressure profile calculating method and then to make an economical oil country tubular goods (OCTG) anti-corrosion design. CO₂ partial pressure is the most important parameter to the oil and gas corrosion research for these wells which contain sweet gas of CO₂. However, till now, there has not been a recognized method for calculating this important value. Especially in oil well, CO₂ partial pressure calculation seems more complicated. Based on Dolton partial pressure law and oil gas separation process, CO₂ partial pressure profile calculating method in oil well is proposed. A case study was presented according to the new method, and two kinds of corrosion environment were determined. An experimental research was conducted on N80, 3Cr-L80 and 13Cr-L80 material. Based on the test results, 3Cr-L80 was recommended for downhole tubing. Combined with the field application practice, 3Cr-L80 was proved as a safety and economy anti-corrosion tubing material in this oil field. A proper corrosion parameter (mainly refers to CO₂ partial pressure and temperature) can ensure a safety and economy downhole tubing anti-corrosion design.

Based on Dolton partial pressure law and oil gas separation process, CO₂ partial pressure profile calculating method in oil well is proposed. An experimental research was conducted on N80, 3Cr-L80 and 13Cr-L80 material. A field application practice was used.

It is necessary to calculate the CO₂ partial pressure properly to ensure a safety and economy downhole tubing (or casing) anti-corrosion design.

The gas and oil separation theory and corrosion theory are combined together to give a useful method in downhole tubing anti-corrosion design method.

Industrial chimneys are a great part of environmental protection in industrial countries. In recent years many of them have been used to carrying away very aggressive gases from boilers and flue gas desulphurisation (FGD) units below acid dew‐point temperature. It is opf very important to modernize the old stacks and protect them against corrosion. The proper anti‐corrosion protection of modern high stacks is also an important technical and economical problem. In this paper the mechanism of acid dew‐point corrosion, as well as construction of industrial chimneys, methods of their anti‐corrosion protection and modernisation are described.

The basic aspects and mechanism of corrosion of steel piles in sea water are briefly discussed. The effects of parameters viz. pH, salinity, dissolved oxygen, temperature and wind velocity responsible for the corrosion of steel piles have been presented. The methods used for corrosion control and the impressed current cathodic protection technique in particular, with its merits, when applied to under‐water marine structures are outlined. The values and importance of potential required at the surface under protection, surface current density requirement and its distribution for the protection of steel structures under different service conditions useful for the design of cathodic protection systems are presented. The characteristics of various types of anode materials with a special reference to the latest platinized (Platinum‐Niobium) niobium anodes, with their merits, over other types of anodes are tabulated. The basic considerations required for the design of cathodic protection and the design of the system have been presented.

The end of this month will see Britain's biggest display of products and processes designed to prevent the onset of corrosion in all its forms. At the Royal Horticultural Society's New Hall, in Westminster, there will be over a hundred stands on view to visitors to the Exhibition which will run from April 27 to 30 inclusive. Here is C.T.'s exclusive preview. Stand descriptions are grouped under various headings, but the fact that a firm's exhibits are described under one heading does not necessarily mean that its interests are confined solely to that group of products. The grouping of exhibitors in this preview is merely intended to facilitate visitors who are interested in particular aspects of corrosion prevention.

One of the most pressing problems of our times is the supply of adequate quantities of drinking water in areas not bestowed with abundant natural resources. Studies have shown the desalting of seawater to be economically sound for certain localities. Of all the available methods, the multi‐stage flash distillation is a proven method. The MSF type desalination plants may be operated independently (single purpose) or linked to power stations (dual purpose). In the MSF type desalination plants, the largest single item of cost is heat exchanger tubes. Design studies have shown that about one‐tenth of a square foot of condensing surface is required to produce one gallon of fresh water per day. For a combined capacity of one billion gallons per day at ¼ sq. ft. of tube, a tube length of 80,000 miles would be required. In MSF type desalination plants, the initial capital cost swallows up to 33% of the money, operating costs about 21% and the remaining 26% goes on power. The colossal amount of heat exchanger surface required in MSF type plants makes it mandatory to investigate new condenser tube materials which may provide ease of fabrication, maximise economy and be abundantly available.

Methods of protecting pipelines from corrosion are discussed in this second part of a paper which has become a source of reference for basic data on cathodic protection for underground systems. Part I appeared in our February issue.

This paper aims to examine total annual cost from economic view mixed materials heat exchangers based on three optimization algorithms. This study compares the use of three optimization algorithms in the design of economic optimization shell and tube mixed material heat exchangers.

A shell and tube mixed materials heat exchanger optimization design approach is expanded based on the total annual cost measured by dividing the costs of the heat exchanger to area of surface and power consumption. In this study, optimization and minimization of the total annual cost is considered as the objective function. There are three types of exchangers: cheap, expensive and mixed. Mixed materials are used in corrosive flows in the heat exchanger network. The present study explores the use of three optimization techniques, namely, hybrid genetic-particle swarm optimization, shuffled frog leaping algorithm techniques and ant colony optimization.

There are three parameters as decision variables such as tube outer diameter, shell diameter and central baffle spacing considered for optimization. Results have been compared with the findings of previous studies to demonstrate the accuracy of algorithms.

The present study explores the use of three optimization techniques, namely, hybrid genetic-particle swarm optimization, shuffled frog leaping algorithm techniques and ant colony optimization. This study has demonstrated successful application of each technique for the optimal design of a mixed material shell and tube heat exchanger from the economic view point.

Cathodic protection for pipelines THE DESIGN, installation and maintenance of pipeline protection systems are services the Cathodic Protection section of Solus Schall Rank Precision Industries Ltd., Phoenix Works, Great West Road, Brentford, Middx., provides on an international basis. Two basic systems are involved in implementing these services, namely ‘galvanic anode’ or ‘impressed current’, and before a choice can be made the following factors must be assessed.

It is a fact that a metallic article or structure must eventually corrode. Whether or not this corrosion causes failure of the item during its anticipated useful life is a matter of economics. On the other hand, mitigating the corrosion so that failures occur after the item has served its useful purposes is a matter of scientific and engineering study. Many instances may be quoted, and generally are quoted, of items that apparently never corrode (these are the successes of corrosion engineering) but, at the same time, there are many more that fail prematurely, and it is a surprising fact that these are not quoted as often as the other type.

Surface preparation—Reasons and Methods To determine the reason why we prepare the metal surface, we first consider the end result we wish to achieve. Exposure to the elements will rapidly corrode metals and lead to destruction by erosion, particularly in salt‐laden air. We must, therefore, bond on to this surface a complete barrier to external destruction by means of a protective coating. (We do not ‘paint the boxes’, we apply a protective coating).