Pipeline calculations

Surface area In the case of underground pipelines, calculation of the superficial surface area can be obtained from the diameter and length of line involved. The superficial surface area should include any offtakes and other... 

Pipeline calculations (pressure drop) 67 Pirie, R. L, 199, 203,207. 208,228 Piston pumps 315,316... 

Conventional pipeline calculations in which "dry" hydrocarbon flashes are performed to determine the hydrocarbon liquid formation the liquid water condensed is estimated using one of the available natural gas water content charts (1, 15), and the Hammerschmidt equation (11) and a graphical correlation are used to... 

The conventional technology of pipeline calculations does not normally predict the carbon dioxide or hydrocarbon content of the water rich phase. These can be estimated by other graphical correlations. 

Hydrogen gas has a higher fuel value than natural gas on a mass basis but not on a volume basis. Thus, hydrogen is not competitive with natural gas as a fuel transported long distances through pipelines. Calculate the heats of combustion of H2 and CH4 (the principal component of natural gas) (a) per mole of each, (b) per gram of each, (c) per cubic meter of each at STP. Assume H20(l) as a product. 

Ellenberger, J. P. 2010. Piping and Pipeline Calculations Manual Construction, Design, Fabrication, and Examination, Amsterdam, Boston Butterworth-Heinemann/Elsevier. Written by an author with 40 years of personal experience as an engineer and instructor, this handbook focuses on the calculations, codes and standards related to piping system design, construction and maintenance. Dozens of worked examples support the text. 

Determine the useful power input needed to overcome the friction losses in a pipeline. Calculate brake kW for pumps and compressors. 

The measurement of a crude oil s viscosity at different temperatures is particularly important for the calculation of pressure drop in pipelines and refinery piping systems, as well as for the specification of pumps and exchangers. 

The above example is a simple one, and it can be seen that the individual items form part of the chain in the production system, in which the items are dependent on each other. For example, the operating pressure and temperature of the separators will determine the inlet conditions for the export pump. System modelling may be performed to determine the impact of a change of conditions in one part of the process to the overall system performance. This involves linking together the mathematical simulation of the components, e.g. the reservoir simulation, tubing performance, process simulation, and pipeline behaviour programmes. In this way the dependencies can be modelled, and sensitivities can be performed as calculations prior to implementation. 

Coal Slurry Pipelines. The only operating U.S. coal slurry pipeline is the 439-km Black Mesa Pipeline that has provided the 1500-MW Mohave power plant of Southern California Edison with coal from the Kayenta Mine in northern Arizona since 1970. It is a 457-mm dia system that aimuaHy deHvers - 4.5 x 10 t of coal, the plant s only fuel source, as a 48.5—50% slurry. Remote control of slurry and pipeline operations is achieved with a SCADA computer system. In 1992 coal deHvery cost from mine to power plant was calculated to be 0.010/tkm ( 0.015/t-mi) (28). 

When constmction is complete, the pipeline must be tested for leaks and strength before being put into service industry code specifies the test procedures. Water is the test fluid of choice for natural gas pipelines, and hydrostatic testing is often carried out beyond the yield strength in order to reHeve secondary stresses added during constmction or to ensure that all defects are found. Industry code limits on the hoop stress control the test pressures, which are also limited by location classification based on population. Hoop stress is calculated from the formula, S = PD/2t, where S is the hoop stress in kPa (psig) P is the internal pressure in kPa (psig), and D and T are the outside pipe diameter and nominal wall thickness, respectively, in mm (in.). 

Frictional Pressure Drop Usually this does not have a significant effect on the reaclor size, except perhaps when the flow is two-phase. Some approximate relations fbe cited that are adequate for pressure-drop calculations of homogeneous flow reactions in pipelines. The pressure drop is given by... 

In analyzing the results on a cathodically protected pipeline, the protection current density and coating resistances should be calculated for individual sections of the pipeline in addition to the on and off potentials, the pipe current, and the resistances at insulating points and between the casing and the pipeline. The results should be shown by potential plots to give a good summary [15] (see Fig. 3-20). 

The values calculated using Eqs. (3-36) and (3-37) are only true for welded pipelines. Extension joints, fittings, and screwed or caulked joints can raise the longitudinal resistance of a pipeline considerably and therefore must be bridged over for cathodic protection. 

The variation in the on and off potentials or the potential difference along the pipeline will usually indicate faults that prevent the attainment of complete cathodic protection. The protection current requirement of the pipeline may be estimated from experience if the age and type of pipeline is known (see Fig. 5-3). Figure 3-20 shows the variation in the on and off potentials of a 9-km pipeline section DN 800 with 10-mm wall thickness. At the end of the pipeline, at 31.84 km, an insulating unit is built in. The cathodic protection station is situated at 22.99 km. Between this and the end of the pipeline there are four pipe current measuring points. The applied protection current densities and coating resistances of individual pipeline sections are calculated from Eqs. (3-40) and (3-41). In the upper diagram the values of... 

Fig. 3-30 Results of intensive measurement on a long-distance pipeline in the region of a holiday with insufficient polarization U = calculated true potential).

Steel constructions and pipelines must either be electrically connected to the reinforcement of reinforced concrete structures or electrically separated. If they are connected, a current density of about 5 mA m should be applied to the external reinforcement and calculated on the total area of the concrete surface. 

A complete solution for calculating the inductive coupling between a high-voltage line and metal conductors (e.g., pipelines) is possible with the help of series expansion [10,11] and computers. The following section provides advice on these calculations. 

Calculation of Pipeline Potentials in the Case of Parallel Routing of a High-Voltage Transmission Line and a Pipeline... 

Usually in calculating ac interference it is assumed that/= 50 Hz, soil resistivity p = 50 O m and with/= 16% Hz due to the greater depth of penetration, p = 30 m. The following distances from the pipeline on both sides of the center of the right-of-way rail are those in which the extent of the interference should be determined ... 

The field strength, E, induced by grounding short-circuit currents in high-voltage overhead power lines or railway power lines, is basic in calculating the pipeline potentials (see Section 23.3.2). The field strength, E, follows from Refs. 2 and 13 ... 

To determine the pipeline potentials, the resultant induced field strengths have to be included in the equations in Section 23.3.2. Such calculations can be carried out with computers that allow detailed subdivision of the sections subject to interference. A high degree of accuracy is thus achieved because in the calculation with complex numbers, the phase angle will be exactly allowed for. Such calculations usually lead to lower field strengths than simplified calculations. Computer programs for these calculations are to be found in Ref. 16. 

Important parameters of a pipeline for calculating pipeline potentials are dealt with in Section 23.3.2. These quantities depend on the frequency,/, of the interfering current and on the material data of the pipeline. These are as follows ... 

With long-term interference from operational currents of high-voltage power lines or railway power and supply lines, the contact voltage must not exceed 65 V [9]. The relevant operational current has to be stated by the operator responsible for the basic calculation. If the calculated pipeline potentials are above 65 V, connection with grounds is always necessary. 

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