pump. In both cases, stuffing boxes shall be site-convertible to a packed
box. Leakage shall be not more than 25 cc/hr for a seal life of not less
than 25,000 hours. Bearing rating shall be not less than 100,000 hours
(L-10 life) at the point of maximum load, as defined by ABMA 9. Sump
cooling shall be by indirect coil. Pump casings shall be designed to allow
the pump barrel assembly to be removed as a unit, from the drive shaft end
to the impeller, without disturbing the main piping or the drive [motor]
[or] [turbine].
2.3.10.2
Pump Base
Pumps shall be supported on structural steel bases that do not require
grouting in order to impart strength to the pump for static and dynamic
loading from the piping system. Bases for pump and drive assembly and
support shall be complete with drain lip and pitched to a low-point drain.
The complete pump and motor assembly shall be shop aligned using shims on
both the pump and motor. Pumps shall be installed on their concrete
foundations where shown on the drawings.
2.3.10.3
Pump Couplings
All pumps shall be furnished with nonlubricated flexible-disk couplings and
a coupling guard. Couplings shall be spacer type to permit removal of the
mechanical seals and limited-end-float-type for pumps with sleeve bearings.
2.3.10.4
Pump Relief Valve
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NOTE: If automatic recirculation valve is utilized,
delete this paragraph.
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Where an automatic boiler feedwater recirculation valve is not used, each
boilerfeed pump shall be arranged for continuous operation and shall be
furnished with a suitable relief valve for bypassing the boiler feed to the
deaerating feedwater tank to maintain a minimum flow of 5 percent under
shutoff conditions. Feedwater regulating valve shall maintain a constant
feed-pump discharge pressure. Valve shall be an internal-pilot-operated
piston valve, single-seated, V port or tapered plug, and shall be adjusted
to maintain within 7 kPa 1 pound of the desired terminal pressure,
regardless of fluctuations in the initial pressure or fluctuations in the
rate of flow. Valve body shall be constructed of bronze with renewable
disks and seats of hardened stainless steel and shall be designed for a
working pressure of not less than [1.72] [_____] MPa [250] [_____] psig. A
position indicator shall be provided with the valve.
2.3.10.5
Pump Shutoff Valve
Each pump shall be fitted with a shutoff valve on the suction inlet line
and with a nonslam check valve and a shutoff valve on the discharge line.
On pump sizes over 3 L/second 50 gpm, an automatic recirculating bypass
valve unit shall be provided on each pump discharge to prevent the pump
from overheating and consequent damage at low flows. Where the automatic
recirculating valve is so designed, it may be used as a combination check
valve and recirculating valve and the separate nonslam check valve may be
omitted.
SECTION 15846A
Page 36
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