sound level and there is no water hammer and so that vibration from
equipment is not transmitted through the piping systems. The fluid systems
shall be designed and constructed to produce less than 85 dBA sound level,
free field, at one meter 3 feet distance from any part of the system in
accordance with ANSI S12.34. Velocities maintained in slurry systems shall
be not less than 1.22 meters 4 feet per second nor more than 3.35 meters 11
feet per second under all conditions in line including low and high flow.
Piping systems shall have high-point vents and low-point drains. Valves
shall be located no higher than 1 1/2 meters 5 feet above maintenance
platforms and a minimum of 2.13 m 7 foot headroom shall be maintained over
walkways. Provide expansion devices and appurtenances to allow for
expansion of the piping system. Piping shall be arranged and routed to be
readily accessible for maintenance. Field connections shall be located to
allow access for disconnection as required for maintenance. On-off control
valves shall be provided in the suction and discharge piping of pumps.
2.10.2.1
Valves
Air and water valves shall be as follows: Valves 50 mm 2 inchesand smaller
shall be Class 200 bronze gate, globe or angle valves conforming to ASTM B
61, valves larger than 50 mm 2 inchesshall be Class 125 cast-iron gate,
globe, or angle valves conforming to ASTM A 126. Slurry valves shall be
Class 150 polyfluorotetraethylene (PTFE) sleeve plug valves, rubber-lined
diaphragm valves with a minimum rating of Class 150, Class 150 semisteel
rubber-lined eccentric plug valves, Class 150 knife gate valves or rubber
sleeve pinch valves. Pinch valves or rubber-lined diaphragm valves shall
be used to modulate slurry flow. The pinch valve elastomers shall be
neoprene reinforced with polyester. Elastomer sleeve diameter-to-length
ratio shall be 1.3 minimum. Pinch valve closure mechanism shall close the
valve from opposite sides of the sleeve simultaneously, with complete valve
closure at the centerline of the pipe, and shall be provided with positive
opening feature. Valves shall be provided with lever or handwheel
operators with adjustable position stop. As used in this specification,
the term "control valve" refers to an assembly, consisting of a valve body
and an actuator, which is used for on-off or modulating opening and closing
of the valve, regulating fluid flow, or pressure in response to signal(s)
from a control system. Control valve bodies shall be as specified.
Provide control valves as required to enable the FGD system to be operated
from the steam plant control room. Control valves shall have indicators
showing position of valve. Control valves shall have manual override to
ensure immediate local control. Manual override shall override coil
without damage to coil. Control valves shall be provided with isolating
valves as necessary to allow for maintenance. Actuators shall be
spring-and-cylinder double-acting cylinder or spring-and-diaphragm type
actuators and shall have long-stroke design or special linkages, adapters
as required for rotary-type valves. Actuators shall be sized as required
for stable operation under maximum pressure drop conditions with 414 kPa
(gage) 60 psig maximum air supply pressure available to actuator. Stable
operation is defined as the ability of the actuator to position and hold
the valve plug, elastomer sleeve or diaphragm accurately without pulsation,
vibration, or sticking. Actuators shall be provided with stem travel
indicator on yoke. Solenoid valves shall conform to the requirements as
specified in paragraph entitled "Solenoid Valves." Provide with each
open-closed control valve a limit switch assembly consisting of two DPDT
switches, one to actuate in the open position and one to actuate in the
closed position. Provide each modulating control valve with a position
transmitter. Limit switches shall conform to the requirements of paragraph
entitled "Limit Switches." Limit switches shall be furnished factory
mounted to their respective control valves. Control valves shall be
SECTION 15864N
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