Installation piping considerations

Pipe Lines Installation of water pipes and gas pipes is another important aspect for furnishing a science laboratory. While installing pipes some of the points that be given due consideration are given as follows ... 

There are no restraints on the secondary piping either inside or outside the containment. The plant proposes to perform an analysis of the risk of secondary pipe whip and, depending on the results, to consider installing pipe restraints. A further consideration is the mechanical substantiation of the safety important pipings and their supports, also with respect to seismic qualification. 

Measurement Requirements. Any analysis of measurement requirements must begin with consideration of the particular accuracy, repeatabihty, and range needed. Depending on the appHcation, other measurement considerations might be the speed of system response and the pressure drop across the flow meter. For control appHcations repeatabihty may be the principal criterion conversely for critical measurements, the total installed system accuracy should be considered. This latter includes the accuracy of the flow meter and associated readout devices as well as the effects of piping, temperature, pressure, and fluid density. The accuracy of the system may also relate to the required measurement range. 

For some applications, either steam or electricity is simply not available and this makes the decision. It is rarely economic to install a steam boiler just for tracing. Steam tracing is generally considered only when a boiler already exists or is going to be installed for some other primary purpose. Additional electric capacity can be provided in most situations for reasonable costs. It is considerably more expensive to supply steam from a long distance than it is to provide electricity. Unless steam is available close to the pipes being traced, the automatic choice is usually electric tracing. 

Ground area and. space requirement.s. Comparisons of the overall space requirements for plants using air cooling versus water cooling are not consistent. Some air-cooled units are installed above other equipment—pipe racks, shell-and-tube exchangers, etc. Some plants avoid such inst ations because of safety considerations, as discussed later. 

Basic to establishing whether power recovery is even feasible, let alone economical, are considerations of the flowing-fluid capacity available, the differential pressure available for the power recovery, and corrosive or erosive properties of the fluid stream. A further important consideration in feasibihty and economics is the probable physical location, with respect to each other, of fluid source, power-production point, and final fluid destination. In general, the tendency has been to locate the power-recoveiy driver and its driven unit where dictated by the driven-unit requirement and pipe the power-recoveiy fluid to and away from the driver. While early installations were in noncorrosive, nonerosive services such as rich-hydrocarbon absorption oil, the trend has been to put units into mildly severe seiwices such as amine plants, hot-carbonate units, and hydrocracker letdown. 

Any obstruction inserted into a duct or pipe that creates a measurable pressure difference can be used as a flow meter. The three basic standardized flow measurement devices presented above are perhaps more suitable for laboratory work than installation as permanent ductwork instruments in ventilation applications. They are sensitive to flow disturbances, relatively expensive, require considerable space, and have a narrow measurement range and a high permanent pressure loss. For these reasons, numerous attempts have been made to develop instruments without these drawbacks. Some of them, like the... 

When in-line detonation flame arresters are installed in single or manifolded vent systems, consideration mnst be given to the design of the system (flame arrester and piping). The following design practices shonld be considered ... 

When using alloy pipe with greater tensile strength than carbon steel, the schedule numbers still apply, but may vary, because it is unnecessary to install thicker walled alloy pipe than is necessary for the strength and corrosion considerations. Schedules 10 and 20 are rather common for stainless steel pipe in low pressure applications. 

Pipework should be easily identifiable in accordance with BS 1719. Where the normal pressure in the pipe exceeds 75mbar, consideration should be given to labeling the pipe with the normal operating pressure. In buildings in which there are no other piped flammable gas supplies it is sufficient to paint the pipe yellow ochre or to band it with appropriately colored adhesive tape. In large complex installations, it is desirable to identify pipe contents more precisely, and in those instances, the base color should be supplemented with a secondary code band of yellow and/or its name or chemical symbol. 

The final selection can be made only after consideration of the first cost of the compressor, motor, starter, aftercooler and receiver. The cost of installation, including foundations, piping and wiring as well as the operating power cost must also be considered. In the example. Table 41.3 provides a basic comparison of the three options. 

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