Pipe-line calculations pressure

TWO-PHASE PRESSURE DROP CALCULATION IN A PIPE LINE PIPE INTERNAL DIAMETER, inch 3.070... 

When the relieving scenarios are defined, assume line sizes, and calculate pressure drop from the vent tip back to each relief valve to assure that the back-pressure is less than or equal to allowable for each scenario. The velocities in the relief piping should be limited to 500 ft/sec, on the high pressure system and 200 ft/sec on the low pressure system. Avoid sonic flow in the relief header because small calculation errors can lead to large pressure drop errors. Velocity at the vent or flare outlet should be between 500 ft/sec and MACH 1 to ensure good dispersion. Sonic velocity is acceptable at the vent tip and may be chosen to impose back-pressure on (he vent scrubber. 

Note when used for pump system balance, this Zhf must be used as a negative number ( — 0.1863) because it is a pressure loss associated with the fluid flowing. For pipe line sizing, the pressure head on the tank of 5 psig and any elevation difference between tank outlet nozzle and pump suction centerline do not enter into the calculations. 

Equation (11) states that the conventional Fanning friction factor, which may be used through Eq. (10) to calculate pipe-line pressure drops, is a unique function of two dimensionless groups for Bingham-plastic fluids. Newtonian fluids represent that special case for which r , and hence the second dimensionless group, is equal to zero. 

V/D of interest, it may be used for the calculation of the relationship between pressure drop and flow rate in a pipe line of any size, provided only that the flow is laminar and that the laboratory data are at the correct temperature. 

In summary, two of the principal approaches which were found useful for the calculation of pipe-line pressure drops have been extended to the problem of predicting power consumption for the agitation of non-Newtonian fluids. Extension of this work is required, but until further data become available, use of the standard power number-Reynolds number charts (with the generalized Reynolds number) is recommended. Between Reynolds numbers of 10 and 70 these charts will provide con-... 

Methods for the calculation of pressure drop through pipes and fittings are given in Section 5.4.2. It is important that a proper analysis is made of the system, and the use of a calculation form (worksheet) to standardize pump-head calculations is recommended. A standard calculation form ensures that a systematic method of calculation is used, and provides a checklist to ensure that all the usual factors have been considered. It is also a permanent record of the calculation. A template for a standard pump and line calculation is given in Appendix G and can be downloaded in MS Excel format from http //books.elsevier.com/companions. Example 5.8 has been set out using this calculation form. The calculation should include a check on the net positive suction head (NPSH) available see Section 5.4.3. 

PRESSURE DROP CALCULATION OF AN INCOMPRESSIBLE FLUID IN A PIPE LINE ... 

Sizing flare piping involves the calculation of the capacity or size of a pipe line and the upstream and downstream pressures. The equations for making these calculations are derived below. 

Example 7.5. The equilibrium liquid from the flash drum at 100°F and 485 psia in Example 7.2 is fed to a stabilizer to remove the remaining hydrogen and methane. Pressure at the feed plate of the stabilizer is 165 psia (1138 kPa). Calculate the percent vaporization of the feed if the pressure is decreased adiabatically from 485 to 165 psia by valve and pipe line pressure drop. 

Fig. 5.23. Time-to-failure data from the long-term hydrostatic pressure creep test on HOPE pipes at 40 °C (continuous line). Calculated relaxation curves for planar state of stress (dotted line). (1) Relaxation after rapid straining (3 % strain in 3 hours). (2) Stress relaxation after slow straining (3 % strain in 30 years)...

The calculation of wall thickness was carried out imder the following conditions stability of polymeric casing shape while pipe-line laying in the ground, durability of casing material imder pressure which is equal to a working one in a pipe-line being framed. 

To provide casing material durability under woiking P in a framed pipe-line, the pipe framing casing is to bear a working pressure of substance pumped over the framed pipe-line. So the calculation of wall thickness is carried out proceeding from permissible strain for a selected material Og, at the same time taking into account the maximum pressure P for a selected material. 

Most line has pipe fittings, such as elbows, tees, reducers. It also has block valves, check valves, or instruments, such as control valve and oriflce flow meter. They will cause pressure drop in tine. In this section, we will discuss how to calculate pressure drop thru pipe fltting, block valve, check valve, and control valve using loss coefficient, K, since their pressure drops are required in hydraulic loop pressure profile calculation. Darby s 3-K. method will be used to calculate these pressure drops [ 12]. It is better than two K method or equivalent line length methods. Fittings and valves pressure drop (in terms of pressure head, H) is calculated by flillowing equation, ... 

Once the diameter is known, the Reynolds number. Re can be computed and the friction factor f obtained from Figure 21. Assuming a straight length of pipe for L = 5(X) ft, N (line resistance factor) can be calculated. Next Gj, is calculated based on the downstream pressure and G/G j evaluated. From Figure 20 the ratio Pj/Pfl can be obtained. Since Pj is known, Pq can then be calculated. The pressure at the inlet of the knock-out drum is given by Pq -I- 0.5 psi. Table 6 provides typical values of resistance coefficients for various pipe fittings. 

Pressure drop through line systems containing more than one pipe size can be determined by (a) calculating the pressure drop separately for each section at assumed flows, or (b) determining the R totals iox each pipe size sep>-arately, and then converting to one selected. size and using that for pressure drop calculations. For example, using... 

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