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4. BOILER PIPING
A. STEAM BOILER PIPING – SINGLE
BOILERS
1. Install steam supply pipes as shown in Figure 4.1. The
minimum quantity and size of supply pipes are
indicated in Table 4.1.
Use Threaded Fittings for Manifold Piping
Figure 4.1: Steam Piping – Single Supply
Connection
NOTICE
Use swing joints to attach to the header to avoid
damage to the boiler due to thermal expansion and
contraction of steam header pipe.
2. Pipe the steam header a minimum of 24" above the
normal water line using swing joints to attach the
risers into the steam header.
NOTICE
• Do not use bushings or concentric reducers in the
horizontal header piping. This will prevent water
from dropping into the equalizer and cause water
carryover into the steam piping.
• Do not reduce the size or number of steam supply
risers below the minimum shown in Table 4.1.
Insufficient or undersized risers can cause damage
to the boiler.
• Do not use a bullhead tee to provide steam supply
to the system. This will cause water carryover into
the steam piping.
INSTALLATION AND OPERATING INSTRUCTIONS
3. Use threaded fittings for manifold piping to provide
flexibility for thermal expansion.
4. Connect the equalizing line as shown in Figure 4.1
assuring that the reducing elbow is facing down and
that any bushings are vertical to prevent water build-
up in the steam header.
5. The use of a Hartford Loop in all installations is
recommended to ensure reliability of the system. A
check is required on the pump discharge of all
pumped return systems.
6. On pumped return systems, install a globe valve after
the pump to allow throttling of the pump discharge.
The pressure downstream of the boiler cock should
be no more than 5 psig above the boiler operating
pressure.
NOTICE
Always locate the steam supply take-off of the main
header between the equalizer and the last boiler
supply riser. Locating the steam supply between the
risers will cause a bullhead tee and cause water
carryover into the system.
7. Pipe the Hartford Loop such that the top of the close
nipple is 2 to 4 inches below the boiler normal water
line.
8. If the boiler feed pump discharge piping is elevated
at any point above the boiler water line, install
spring-loaded check valves at both the pump
discharge and at the connection to the boiler.
Table 4.1:
Steam Supply and Header Pipe Sizing
Number of
Boiler
Supply
Supply
Model
Size (NPS)
Connections
88
1
2
118
1
2
1
2-1/2
147
2*
2*
1
2-1/2
177
2*
2*
1
3
206
2*
2*
1
3
236
2*
2*
1
3
288
2*
2-1/2*
*Dual supplies may be used in lieu of larger single supply.
Header
Equalizer
Evaporation
Size (NPS)
Size (NPS)
Rate (GPM)
2
1-1/4
0.11
2
1-1/4
0.15
2-1/2
1-1/4
0.19
2-1/2
1-1/4
0.23
3
1-1/4
0.27
3
1-1/4
0.31
3
1-1/4
0.37
9
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