Pressure pipeline applications

Pilot-operated PR valves can be specified for blowdown as low as 2%. This is an advantage for main gas pipeline and pressure storage applications, where the narrow range of pressure cycling minimizes product losses resulting from a release. 

Retrograde condensation plays an important role in technical applications, for example, in oil production, high-pressure pipelines, refrigeration processes and in natural gas reservoirs, where temperature and pressure are high enough to produce critical conditions. 

When weak chlorine is handled, as in the evacuation or purging of low-pressure pipelines, an acid seal would quickly be diluted by absorption of water from wet air. In this case, water-sealed compressors are used. Ferrous-metal construction is out of the question for this application. The materials must be suitable for use in wet chlorine service. Titanium and steel lined with titanium or a ceramic are frequently used. 

In industrial construction of pressure pipelines, various high-molecular polypropylenes, such as homopolymers (PP-H, type 1) and statistical copolymers (PP-R, type 3) are used. Block copolymers (PP-B, type 2) are less suitable for such applications because of their low creep resistance. Hexagonal )S-crystalline PP-H, in contrast to normal monoclinic oc-PP-H, is created hy special nucleation and optimum processing. This material meets the requirements of all international standards regarding PP homopolymers and has DIBt approval [831]. 

The majority of industrial slurry-transport installations tend to be free of cavitation and related problems with pump suction performance, but in many other applications cavitation is important and must be considered in system design. In disposal pipelines operated by the dredging industry and also in pipeline applications such as those used by the phosphate extraction industry (for example in Florida, U.S.A.), the first (upstream) pump is susceptible to highly sub-atmospheric suction pressures (see Fig. 1). In these cases, cavitation is a common occurrence, and may be significant in determining the costs of operation. 

For high-pressure pipeline repair applications, unidirectional alignment of the reinforcing glass and the pultmsion process has clear advantages. 

A limited number of stodies have been conducted on the internal repair of steel pipelines using composite material systems. As a consequence, only a few industries have used composite technologies for internal repair. In their report, Bruce et al. (2006) indicated that internal repair would have the best economics for underwater repair locations as it reduces out-of-service time and does not require divers and habitats. Such economics arise because the majority of the gas transmission line companies in the United States consider the ability of the pipeline to remain in service during internal repair to be very important. Moreover, they would considCT internal repair, even if the pipeline needs to be out of service (no flow), only if the pipeline remains pressurised and the line can still be inspected by a pipe inspection gauge after repair. However, these companies have indicated that they would consider performing a repair from inside the pipe once a proven and accepted internal repair system becomes available. Thus, the selection of the most appropriate technique of renovation, particularly on the internal repair of high-pressure and deep water pipeline applications, is a critical and ongoing issue. 

Potable Water RO and NF both play a major role in providing potable water, defined either by the WHO criterion of <1000 ppm total dissolved solids (TDS) or the U.S. EPA limit of 500 ppm TDS. RO is most prominent in the Middle East and on islands where potable-water demand has outstripped natural supply. A plant awaiting startup at Al Jubail, Saudi Arabia produces over 1 mVs of fresh water (see Table 22-17). Small units are found on ships and boats. Seawater RO competes with multistage flash distillation (MSF) and multieffect distillation (MED) (see Sec. 13 Distillation ). It is too expensive to compete with conventional civil supply (canals, pipelines, w ls) in most locations. Low-pressure RO and NF compete with electrodialysis for the desalination of brackish water. The processes overlap economically, but they are sufficiently different so that the requirements of the application often favor one over the others. 

The use of corrosion-resistant materials and the application of corrosion protection measures are in many cases the reason that industrial plants and structures can be built at all. This is particularly so in pipeline technology. Without cathodic protection and without suitable coating as a precondition for the efficiency of cathodic protection, long-distance transport of oil and gas under high pressures would not be possible. Furthermore, anodic protection was the only protective measure to make possible the safe operation of alkali solution evaporators (see Section 21.5). 

Further chapters cover in detail the characteristics and applications of galvanic anodes and of cathodic protection rectifiers, including specialized instruments for stray current protection and impressed current anodes. The fields of application discussed are buried pipelines storage tanks tank farms telephone, power and gas-pressurized cables ships harbor installations and the internal protection of water tanks and industrial plants. A separate chapter deals with the problems of high-tension effects on pipelines and cables. A study of costs and economic factors concludes the discussion. The appendix contains those tables and mathematical derivations which appeared appropriate for practical purposes and for rounding off the subject. 

PRESSURE SYSTEM Defined in the Pressure System Safety Regulations 2000 as a system containing one or more pressure vessels of rigid construction, any associated pipework and protective devices the pipework with its protective devices to which a transportable gas container is, or is intended to be, connected or a pipeline and its protective devices which contains or is liable to contain a relevant fluid, but does not include a transportable gas container. Here relevant fluid is steam any fluid or mixture of fluids which is at a pressure of >0.5 bar above atmospheric pressure, and which fluid or a mixture of fluids is a gas, or a liquid which would have a vapour pressure of >0.5 bar above atmospheric pressure when in equilibrium with its vapour at either tlie actual temperature of the liquid or 17.5°C or a gas dissolved under pressure in a solvent contained in a porous substance at ambient temperamre and which could be released from the solvent with the application of heat. 

Poppet valves are typically used for low compression ratio applications, such as pipeline booster compressors. As the pressure differential increases across each of the individual poppets, they lift and allow gas to pass through the flow openings in the stop plate. 

Compressed air lines are very susceptible to a combustion gciienition e.xplosion, fueled by oil or cliar on tlie pipe walls. E.xplosions in pipelines c ui cause considerable damage. Pipelines witliin wliich gas, vapor, or dust explosions can occur must be designed to have sufficient mechanical streiigtli to withstand pressure or stress beyond tliat required by the application. 

Expansion turbines are related in many design features to the centrifugal compressor. The key exception being that the turbine receives a high pressure gas for expansion and power recovery to a lower pressure and is usually accompanied by the recovery of the energy from the expansion. For example, applications can be (1) air separation plants (2) natural gas expansion and liquefaction (for gas let-down in pipeline transmission to replace throttle valves where no... 

Atomic power production The necessity for avoiding contamination of operative liquids, together with other requirements which must be met in selecting constructional materials in this highly specialised field has resulted in the choice of austenitic steels for applications in heat exchangers, pressure vessels, pipelines and fuel processing. 

Turbo-alternators These find an application in pipeline cathodic protection systems, particularly where the liquid or gaseous product in the pipeline can be used as a fuel. The turbo-alternator is usually supplied as part of a complete and fully assembled package incorporating fuel pressure controls, filters, a.c./d.c. conversion and d.c. output controls. System capacity would typically fall within the range 200-3(XX)W. 

Equations 5.37, 5.38 and 5.39 for solid velocity and pressure drop ate applicable only in the absence of electrostatic charging of the particles. Many materials, including sand, become charged during transport and cause the deposition of a charged layer on the surface of the pipe. The charge remains on the earthed pipeline for long periods but can... 

In Section II,C we have deliberately chosen a simple set of problem specifications for our steady-state pipeline network formulation. The specification of the pressure at one vertex and a consistent set of inputs and outputs (satisfying the overall material balance) to the network seems intuitively reasonable. However, such a choice may not correspond to the engineering requirements in many applications. For instance, in analyzing an existing network we may wish to determine certain input and output flow rates from a knowledge of pressure distribution in the network, or to compute the parameters in the network element models on the basis of flow and pressure measurements. Clearly, the specified and the unknown variables will be different in these cases. For any pipeline network how many variables must be specified And what constitutes an admissible set of specifications in... 

The final application or requirements (e.g., determination of free-settling velocity y. minimum fluidization velocity Vm minimum transport velocity Vfmm, and/or pipeline air pressure drop Apt)... 

From Table 3 it can be seen that by optimizing the configuration of pipeline, it is possible to reduce pressure loss, air flow, transport velocity, and hence, pipe/bend wear. Depending on hardware requirements and reliability, which would to some extent govern the maximum operating pressure of the system (e g., say, 400 or 500 kPag), Pipeline Nos. 5 or 6 could be selected for this long-distance application. However, if diverter valves are required at the end of the pipeline, it may be more convenient to select Pipeline No 5 (i.e., D1 = 154 mm instead of 203 mm). 

Good flow splitting design is dependent on the accurate prediction of the pressure drop caused by the various bends, branches and straight sections of pipe. This can be achieved by employing the above branch model(s), proven for the particular material and application, coupled with the accurate pipeline test-design procedure described in Sec. 2.4 of this chapter. 

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