TM 5-810-15
CHAPTER 8
PIPING SYSTEMS
diagram is shown in figure 8-3.
8-1. General.
d. Fuel gas. The fuel gas system reduces gas
This chapter addresses the criteria for the steam
pressure from the supplier*s pipeline, totalizes flow
plant piping systems. The design of the steam plant
to the plant, removes impurities from the gas,
piping will be in accordance with the ASME B31.1.
allows manual isolation of the plant from the
Gas piping will be in accordance with ASME
supply, provides visual indication of plant gas
B31.8. Reference table 8-1 for piping system
pressure, and electrically isolates the plant piping
design notes.
from the buried supply piping.
e. Fuel oil. The fuel oil system includes pumps to
8-2. System descriptions.
move oil from outdoor storage tanks to the plant
a. Main steam. The main steam system delivers
header. The functions performed by the fuel oil
steam from the boiler outlet connections to the
system are similar to those listed for the gas
process. The main steam system consists of: piping
system. Since oil is stored on site and since there is
from each boiler outlet connection, superheating
recirculation back to the fuel oil storage tank, more
equipment (superheated boilers only), a common
than one totalizing flow meter is needed to
main steam line headered to the individual boiler
calculate the amount of oil burned.
outlets, and piping which transports the steam to
f. Blowdown heat recovery. The blowdown heat
the process. On superheated steam units the super-
recovery system recovers part of the heat available
heating equipment, which is an integral part of the
in boiler blowdown water and discharges the unus-
boiler, consists of a primary superheater section, a
able high-solids content water. The blowdown heat
desuperheater, and a secondary superheater. The
recovery system consists of: blowdown regulation
system diagram is shown in figure 8-1.
equipment, a flash tank, a blowdown recovery heat
b. Low pressure steam. The low pressure steam
exchanger, and interconnecting piping. The system
system provides steam for use within the steam
diagram is shown in figure 8-4.
plant. These uses include deaerator (DA) pegging
g. Instrument air. The instrument air system
steam, sootblowing steam, steam coil air prehea-
supplies air to the pneumatic instruments and
ters, boiler feed pump turbine drives, and feed-
control devices throughout the plant. The instru-
water heaters. The low pressure steam system
ment air system consists of: instrument air com-
consists of: steam pressure reducing station, DA,
pressors, aftercoolers, air drying equipment, in-
sootblowers, steam coils, turbine drives, feedwater
strument air receiver, baghouse air receiver (when
heaters, and interconnecting piping. The system
required), and interconnecting and distribution
diagram is shown in figure 8-2.
piping. The system diagram is shown in figure 8-5.
c. Feedwater. The feedwater system collects re-
h. Plant air. The plant air system supplies air for
turning process condensate, treats raw water for
pneumatic tools, maintenance uses, and other uses
makeup to the boiler, collects returning condensate
throughout the plant. Plant air may also be used for
from in-plant processes, conditions the condensate
sootblowing and igniter atomizing purposes when
and makeup to remove corrosive gases, heats the
required. The plant air system consists of: plant air
water, and delivers it to the boiler economizer. The
compressors, aftercoolers, oil separating equipment
feedwater system consists of: water treatment
on crosstie to instrument air system, plant air
equipment to condition raw water for makeup to
receiver, sootblower air receiver (when required),
the boiler, a treated water and condensate storage
atomizing air regulating station (when required),
tank, treated water and condensate pumps to
and interconnecting piping. The system diagram is
deliver water to the DA, a blowdown recovery heat
shown in figure 8-6.
exchanger, a DA to remove the entrained corrosive
i. Boiler vents and drains. Boiler vents and
gases from the water, boiler feed pumps to increase
drains provide the means by which the boiler is
the pressure of the water and deliver it to the
vented and drained during startup and maintenance
boiler, feedwater heaters to heat the water and
operations. The system consists of piping from the
protect the boiler economizer against acid conden-
vent and drain connections on the boiler to the
sation of the flue gas at low loads, flow regulating
appropriate disposal points.
stations, and interconnecting piping. The system
8-1
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