3.1.8
Pipe Expansion
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NOTE: Detail expansion loops on the drawings.
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Expansion loops and pipe guides shall be installed where indicated.
3.1.9
Valves
Valves shall be installed at locations indicated and where specified. Gate
valves shall be used for isolation service unless otherwise indicated or
specified. Globe valves shall be used for throttling service unless
otherwise specified. Valves shall be installed with stems horizontal or
vertical, except steam nonreturn valves shall be installed as specified.
Gate valves used as shutoff valves in the boiler lines to and from steam
headers, and elsewhere as indicated, shall be the chain operated type if
walkways are not provided for their operation. Chain operated valves shall
have sufficient chain for easy reach of the operating personnel from the
operating floor or walkway. Gate valves 200 mm 8 inches and larger used on
high pressure steam lines, and elsewhere as indicated, shall be provided
with a valve bypass integral with the valve body.
3.1.9.1
Back Pressure Relief
Backpressure valve shall be set to exhaust at the pressure indicated.
3.1.9.2
Steam Pressure Reducing
Steam pressure reducing valve shall be adjusted to maintain desired
terminal pressure, regardless of fluctuations in the inlet steam pressure.
Steam pressure reducing valves shall fail closed. Pilot, or auxiliary
operated valves using steam for operating medium, or sliding gate and plate
valves shall be provided. Steam pressure reducing valve shall be installed
with strainer, 3 valve bypass, and safety valve as indicated. Where steam
heater, the valve shall be of pneumatic pilot operated type. Sensing line
shall be connected to the steam space in the deaerator.
3.1.9.3
Thermostatic Regulating
Thermostatic regulating valve to control temperature of water within hot
water generator, by regulating steam supplied to the heating coil, shall be
provided in the steam supply line to each generator.
3.1.10
Flow Meter
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NOTE: Specify which meters should receive 3-way
bypass to maintain service during a meter service or
replacement (suggest that fuel oil flow meters have
a 3-way valve bypass if service is critical.)
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Flow meter shall be installed in straight line pipe of at least [_____]
pipe diameters to maintain accuracy. [A 3-way valve bypass shall be
provided for [_____] flow meters.]
SECTION 15561A
Page 99