Piping operations

Although there are several limits which apply to heat pipe operation, these generally lend themselves to specific design solutions or occur at sufficiently high levels of performance to permit a wide latitude of practical appHcations. The envelope of these limits is shown generically in Figure 3. 

In each case, select the material for a 50 mm pipe operating at approximately 2 bar pressure. 

Those that reduce the number of incidents. Such as sound mechanical design of equipment and piping operating and maintenance procedures, and operator training. 

According to the vendor, the capital costs for the treatment system include a 200-actual cubic-feet-per-minute (ACFM) vacuum pump, two transfer pumps, a carbon steel knockout pot, and associated instrumentation and piping. Operation and maintenance costs for the system include estimates for additional granular activated carbon (GAC) units, liquid- and vapor-phase analysis, weekly monitoring, electricity, and routine maintenance. These costs vary, depending on the monitoring requirements, contaminant concentrations, and other variables (D13124Y, p. 492). 

Corrosion rates are expressed in terms of inches per year of surface wastage and are used to provide a corrosion allowance in the design thickness of equipment such as vessels and pipes. Operators will often use data based on historical experience from plant operations to aid them in determining appropriate corrosion allowances. Alternatively, corrosion charts are widely available that give corrosion rates for many combinations of materials of construction and process fluids, and normally a range of values will be provided for various process temperatures. In some instances, particularly where there is a mixture of chemicals present, appropriate data may not exist and corrosion tests may be necessary in order to determine the suitability of equipment. Operators should be able to demonstrate the use of corrosion allowances in equipment specification and design. The sources of data used should be traceable. 

A loop reactor is used for the bioconversion of methane to produce biomass used, e.g., as fish meal. This is a large-diameter pipe operated at high liquid circulation velocity with the 02/CH4 feed injected at several locations along the reactor. Cooling of the exothermic aerobic fermentation is accomplished by external heat exchangers. Static mixers are used to maintain gas dispersion in the liquid. 

An alternative version of the same expression describing flow-induced shear stresses for a circular pipe operating in the turbulent flow regime is described by the relation (6)... 

Therefore let us instead consider the more practical case of the tertiary current distribution. Based on the dependency of the Wagner number on polarization slope, we would predict that a pipe cathodically protected to a current density near its mass transport limited cathodic current density would have a more uniform current distribution than a pipe operating under charge transfer control. Of course the cathodic current density cannot exceed the mass transport limited value at any location on the pipe, as said in Chapter 4. Consider a tube that is cathodically protected at its entrance with a zinc anode in neutral seawater (4). Since the oxygen reduction reaction is mass transport limited, the Wagner number is large for the cathodically protected pipe (Fig. 12a), and a relatively uniform current distribution is predicted. However, if the solution conductivity is lowered, the current distribution will become less uniform. Finite element calculations and experimental confirmations (Fig. 12b) confirm the qualitative results of the Wagner number (4). 

A clamp-type pipe joint connector failed a short time after it was put into service. This clamp, shown in Figure 7.48, had been used to join two ends of NPS 8 carbon steel steam piping, operating at a pressure of approximately 11 MPa (1600 psi). The boiler feedwater used in this process had been softened by cation exchange (Ca <-> Na) and was fully deaerated. The feedwater was recycled water from an oilfield operation and contained several thousand ppm dissolved chlorides. The steam was 80% quality and at a temperature of approximately 330°C. 

Three major kinds of steel are used for large diameter line pipe operating under extreme climatic... 

The UV Region. The results for the relative cross sections of potassium vapor in the energy region of 210-400 nm are shown in Figure 3. Because of strong absorptions in this wavelength region the vapor pressure of potassium in the heat-pipe could not be reduced to the point such that the heat-pipe operation condition could still be sustained. The isothermal zone is thus not established. Therefore, only relative data are measured in the present work. 

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