Cross-country pipelines

This article presents an overview of the causes and frequency of failures for submarine and cross-country pipelines handling oil and natural gas. It gives several tables and charts which include information on the type of pipeline, the cause of the failure, and the number of failures. Data from failures in the US and the North Sea are included. Failure rates based on the total length of piping are calculated. 

Where a.c. supplies exist, transformer-rectifiers are the most economical source of d.c. for cathodic protection systems. In the case of pipelines, standard transformer-rectifiers, either oil or air cooled, can be employed. They range in size from 5A, 5V for small systems to 100 A, 48 V for major pipeline schemes. A typical output for a well-coated cross-country pipeline in the UK would be 5 A, 48 V. In the case of sea-water jetties where the voltage required is usually low because of the lower sea-water resistivity, a typical rectifier size for a major installation would be 500 A, 18 V. For offshore pipelines and loading platforms where a fire hazard exists, it is usual to employ certified flameproof or intrinsically safe rectifiers to overcome any possibility of fire hazard should faults develop in the unit. 

The method just outlined and illustrated is route specific. It is very flexible and simple to use. It can also be easily computerized if the GP data can be fed in as numerical values. Here we have illustrated its use in the context of a cross-country pipeline, such as a crude oil, products, or perhaps slurry pipeline, which might be commonly encountered by chemical engineers. The method is completely adaptable to any hydraulic flow problem and could be used equally well for a short in-plant pumping system analysis. It can help the designer of flow systems to avoid sometimes subtle traps for slack flow and siphons that might not be immediately obvious if the mechanical energy equation is applied only once between the initial and final points of the flow system. 

The generic coating systems commonly used for cross country pipelines are as follows ... 

A gas stream containing 40.0 mole% hydrogen. 35.0% carbon monoxide. 20.0% carbon dioxide, and 5.0% methane is cooled from 1000 C to 10 C at a constant absolute pressure of 35.0 atm. Gas enters the cooler at 120 m /min and upon leaving the cooler is fed to an absorber, where it is contacted with refrigerated liquid methanol. The methanol is fed to the absorber at a molar flow rate 1.2 times that of the inlet gas and absorbs essentially all of the CO2, 98% of the methane, and none of the other components of the feed gas. The gas leaving the absorber, which is saturated with methanol at —12 C, is fed to a cross-country pipeline. 

Two-phase flow often presents design and operational problems not associated with liquid or gas flow. For example, several different flow patterns may exist along the pipeline. Frictional pressure losses are more difficult to estimate, and in the case of a cross-country pipeline, a terrain profile is necessary to predict pressure drops due to elevation changes. The downstream end of a pipeline often requires a separator to separate the liquid and vapor phases, and a slug catcher may be required to remove liquid slugs. 

The capital investment figures assume the development of a new site with all necessary auxiliary facilities such as loading docks, storage tanks, utilities generation, cross-country pipelines, underground storage, etc. In addition, an allowance for working capital at 10% sales is in-... 

A.S. Khanna. Coating technology for cross-country pipelines. Finish, 2006, 1(2), 37-. ... 

Chemical Composition of Various Steels Used for Underground Cross-Country Pipelines... 

Cross-country pipelines travel through all types of terrain and through desolate and populous areas. In keeping with the purpose of ANSI/ASME B31.8 to protect the... 

Fuel products are delivered to site from ships or via cross-country pipeline and loaded into bulk tanks. Product from bulk tanks are loaded onto road tanker for dispatch. 

As with vandalism, this type of theft can be deterred using basic security measures, although cross-country pipelines are difficult to defend since they are almost entirely in public areas. 

CO2 corrosion is an important parameter, particularly in the design of cross-country pipelines. Although dry CO2 is noncorrosive, CO2 in the presence of water forms carbonic acid, which is corrosive to the carbon steel material. The degree of corrosion largely depends on the partial pressure of carbon dioxide, the pH of the flowing fluid, and the temperature of the fluid. 

Normally, CO2 corrosion is possible if water is present in the system. It is expected that the nonwet surface of the pipeline (not wet with water) will have no CO2 corrosion however, this is not the case. In a cross-country pipeline, water condenses as a result of heat loss, and free water is formed. This free water behaves as a mist and wets the dry surface of the pipe. CO2 corrosion of the dry area depends on the rate of water condensation and is defined as a condensation factor. 

It should be noted that this two-phase correlation has not been developed for cross-country pipelines. This program is to be used to design plant battery limit piping. This calculation does not attempt to establish the impact of temperature (heat loss/gain) simply because the impact can only be established once the full fluid dynamics are available. For example, if there is heat loss, some liquid will condense, and vapor and liquid physical properties will change. It is not possible to calculate these without full fluid properties. 

A 15,000-m-long cross-country pipeline is transporting a fluid with the following properties ... 

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