Piping requirements

Enough space must be available to properly service the flow meter and to install any straight lengths of upstream and downstream pipe recommended by the manufacturer for use with the meter. Close-coupled fittings such as elbows or reducers tend to distort the velocity profile and can cause errors in a manner similar to those introduced by laminar flow. The amount of straight pipe required depends on the flow meter type. For the typical case of an orifice plate, piping requirements are normally Hsted in terms of the P or orifice/pipe bore ratio as shown in Table 1 (1) (see Piping systems). 

Piping required to have a sensitive leak test shall be tested by the gas- and bubble-formation testing method specified in Art. 10, Sec. V of the ASME Code or by another method demonstrated to have equal or greater sensitivity. The sensitivity of the test shall be at least (100 Pa mL)/s [(10 atm mL)/s] under test conditions. If a hydrostatic pressure test is used, it shall be carried out after the sensitive leak test. 

High in stalled co.sts. The incremental piping required for the steam supply system and the condensate return system must be installed, insulated, and, in the case of the supply system, additional steam traps are often required. The tracer itself is not expensive, but the labor required for installation is relatively high. Studies have shown that steam tracing svstems typically cost from 50 to 150 percent more than a comparable electric tracing system. 

Another method of test is to test all sections simultaneously. In this method, the weight flow through each section is maintained in the same proportion. A separate gas cooler is required for each stream and the loop must have sufficient capacity to enable stable conditions to be obtained. In this system, the machine is tested as fully built but requires extensive shop test space to accommodate the multiple gas coolers and large test-loop piping required, if there are several sidestreams. 

Vertical thermosiphon Capable of very high heat transfer rates. Compact simple piping required. Low residence time in heated zone. Not easily fouled. Good controllability. Maintenance and cleaning can be awkward. Additional column skirt required. Equivalent to theoretical plate only at high recycle. 

FBE-coated pipe requires careful handling from factory to the pipe trench to avoid mechanical damage. Repairs are undertaken with either trowel or brush-applied, liquid two-pack epoxy resin-based paints or by melt sticks of compressed powder. 

Ignoring the volume accupied by the sand—about 0.2% of that occupied by the air—the cross-sectional area of the pipe required is (0.20/30) = 0.0067 m2 and thus ... 

Flashing liquids escaping through holes and pipes require special consideration because two-phase flow conditions may be present. Several special cases need consideration.17 If the fluid path length of the release is short (through a hole in a thin-walled container), nonequilibrium conditions exist, and the liquid does not have time to flash within the hole the fluid flashes external to the hole. The equations describing incompressible fluid flow through holes apply (see section 4-2). 

This procedure based on the friction factor chart is too stringent for large-diameter vessels, which behave nearly like smooth pipe, requiring inordinately large values of Re. 

High installed costs. The incremental piping required for the steam supply system and the condensate return system must be installed, insulated, and, in the case of the supply system, additional... 

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