for the warmup. Make sure condensate drains freely during the warmup period,
a s this will reduce the possibility of water hammer.
( d ) After pressure is equal on both sides of the valve, open main valves
f u l l y and close bypass valves, if provided.
( e ) Check trap operation. Close bypass valves as soon as dry steam
s t a r t s discharging through the valves.
( f ) Check manually operated vents. When all air has been released and
steam is being discharged, close manual vents.
( g ) Start operation of the draining equipment ( p u m p s , steam ejectors) in
sump pits and manholes.
During the warmup period, c h e c k for the following
2.2 Warmup Precautions.
( a ) Action of expansion joints or loops
( b ) Action of supports, anchors, guides, and hangers
3 NORMAL OPERATION. C o n t r o l and regulate the use of steam at the points of
usage, when possible, to prevent frequent warming and cooling of the main
d i s t r i b u t i o n system. Make certain steam traps are working properly,
d i s c h a r g i n g only condensate and air. E n s u r e correct operation of associated
e q u i p m e n t , such as pumps, pressure reducing stations, valves, traps,
s t r a i n e r s , and auxiliary equipment, which are addressed elsewhere in this
manual . C h e c k operation of automatic air vents to see that the air
a c c u m u l a t e d in the high points of the system is being discharged. Check
operation of draining equipment (pump, steam ejectors) in sump pits and
manholes. Make sure manhole vents are unrestricted, and tunnels and trenches
a r e kept dry and properly ventilated. I n operation, t h e r e is always a certain
a m o u n t of leakage from piping or infiltration through conduit seals. If
v e n t i l a t i o n is not adequate, the enclosed air becomes saturated with moisture
which can produce corrosion. I n underground conduits of reinforced concrete
c o n s t r u c t i o n , the steel may be corroded by moisture infiltration. Once
c o r r o s i o n starts, the process is hastened because the expansive force of the
f e r r o u s oxide, resulting from the corrosion of the steel, breaks away the
c o n c r e t e surface. This exposes more metal, and the process keeps on at an
a c c e l e r a t e d rate. In aboveground systems, m a k e sure the following criteria
(a) Supporting structures do not settle or shift in position.
( b ) Insulation covering maintains its mechanical and watertight
( c ) Insulation remains dry and in good physical condition.
4 SYSTEM SHUTDOWN. The principal reason for a shutdown is energy
conservation; a secondary reason is for maintenance. Because of steam