Large diameter pipelines

For long distance gas transmission and large diameter pipelines, various forms of the Panhandle formula are widely used. One variation, the modified Panhandle formula, is given by... 

For these reasons and other complex influences (e.g., large-diameter pipelines, particle-wall friction, particle shape, bends, etc.), it has been accepted that if high accuracy is needed, then some form of empiricism must be adopted. The preferred test-design procedure is listed below. 

Developing a method for manufacturing large-diameter pipelines... 

The ACTI and delivered cost-of-gas equivalence of pipelines of various diameters is therefore only one of the major factors that affect the feasibility of a solution. Other factors of paramount importance are wellhead cost, wellhead netbacks, and the ability of a market to absorb the incremental increase of supply, which for large diameter pipelines is in the range of 20 to 30 billion cubic meters per year. Lower wellhead cost extends the feasibility radius of a gas field large diameter pipelines may be able to reach further at reasonable delivered cost. However, markets may set limits on the absorption of the massive increase in supply that is inherent to large diameter pipelines. The absorption capacity of a market may spell doom... 

The opposite of the large diameter pipeline with little axial or radial mixing is the perfect backmixed reactor with instantaneous mixing and uniformity. For polystyrene reactors with several hours of residence time, complete mixing in 1-2 min is usually adequate to satisfy a practical definition of perfectly mixed. The probability of exit of any fluid element from this type of reactor is independent of when it entered. The residence time distribution is exponential and the molecular weight distribution in the case of no termination is Mw/Mn = 2.0, which will spread out to 2.3 when chain transfer controls. If product requirements necessitate a narrower residence time distribution, one can utilize several of these reactors in series. This becomes necessary to control the grafting distribution in rubber modified polystyrene. 

The indicator dilution method is a technique used to determine flow rates of fluids in channels for which devices like rotameters and orifice meters cannot be used (e.g., rivers, blood vessels, and large-diameter pipelines). A stream of an easily measured substance (the tracer) is injected into the channel at a known rate and the tracer concentration is measured at a point far enough downstream of the injection point for the tracer to be completely mixed with the flowing fluid. The larger the flow rate of the fluid, the lower the tracer concentration at the measurement point. 

Three major proposals have been advanced which would provide large diameter pipeline transportation for North Slope gas as well as that gas which may become available in Canada s Northwest frontier areas. The Gas Arctic Systems group has proposed a 1550 mile system which would connect the Prudhoe Bay area with an extension of the existing Alberta Gas Trunk Line system in Alberta, Canada. This system could make gas available to U.S. West Coast and Midwest markets through pipeline interconnections with existing pipeline systems. Spon-... 

Inhibitors act to control corrosion, particularly in piping systems. They form a very thin (perhaps monomolecular) adsorbed layer that acts as a barrier. Film-forming amines are a common example. Because inhibitors may locally de-adsorb, they are usually continuously injected. For large-diameter pipelines, batch inhibition may be necessary. Inhibition is usually not permitted in processes for high-purity products. 

The use of short and small-diameter nozzles to connect the main equipment units and elimination of lengthy large-diameter pipelines in the primary circuit, to exclude loss of coolant accidents initiated by large and medium-breaks in the primary circuit ... 

By-design elimination of large-diameter pipelines in the primary circuit the use of leak restricting devices for coolant outflow as well as in the absence of inter circuit leak-tightness of the steam generator ... 

A flange-mounted process immersion probe for transmission measurement with deeper sampling is available for sampling reactors or very large diameter pipelines (Figure 37.26). 

Figure 8-22. Impressed current CP installation of the internal surface of large diameter pipeline.

Most major urban utilities typically have several large-diameter pipelines of different ages, installed in soils of varying corrosivity, operated and pressurized to different levels, possibly overloaded and deteriorated to unknown levels. Many of the records about the pipelines in major urban areas are either difficult to find or lost over the years, and arc often not readily available. Proactive utilities are beginning to compile the data and create databases with basic pipeline information, for example, age, material, pipeline plan and profile drawings, etc., and potential consequences of pipe failure at various locations in the system. 

Many large-diameter pipelines owned by public utilities, power generation facilities, and industrial sites are located in areas where any excavation is challenging or undesirable. For these types of limited access pipes, and especially in cases where targeted repairs of distressed pipes are to take place, the use of carbon fiber-reinforced polymer (CFRP) lining becomes the most cost-effective and efficient repair or upgrade solution. 

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