750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
3-15
3.9 — Preparation for Extended Layup
The condition does not generally occur during normal firing operation, because the high temperature of operation
vaporizes any condensation. However, proper boiler operation must be maintained, especially with a hot water
boiler, to prevent the flue gases from falling below the dew point.
At the start of layup, thoroughly clean the fireside by removing any soot or other products of combustion from the
tubes, tube sheets, and other fireside surfaces. Brushing will generally suffice. Sweep away or vacuum any accumu-
lation. The fireside surfaces may be flushed with water. However, all moisture must be eliminated after flushing and
the surface dried by blowing air or applying some form of heat. It is good practice to protect the cleaned surfaces
by coating them with an anti-corrosive material to prevent rust.
Swing open the boiler head at the stack end of the unit to prevent flow of warm, moist air through the boiler tubes.
To prevent condensation from forming in the control cabinet, keep the control circuit energized. For extended
layup periods, especially where high humidity or large swings in ambient temperature occur, the control should be
removed and stored in a dry atmosphere.
Dry storage
is generally employed when the boiler will be out of service for a significant period of time, or where
freezing temperatures may exist. In the dry storage method the boiler must be thoroughly dried because any mois-
ture would cause corrosion. Both fireside and waterside surfaces must be cleaned of all scale, deposits, soot, etc.
Steps must be taken to eliminate moisture by placing moisture-absorbing materials such as quick lime (at 2 pounds
for 3 cubic feet of volume) or silica gel (at 5 pounds for 30 cubic feet of volume) on trays inside the vessel. Fireside
surfaces may be coated with an anti-corrosive material, grease or tar paint. Refractories should be brushed clean
and wash-coated. All openings to the pressure vessel, such as manhole and handholes, should be shut tightly. Feed-
water and steam valves should be closed. Damper and vents should be closed to prevent air form reaching fireside
surfaces. Periodic inspection should be made and absorption materials renewed.
Wet storage
is generally used for a boiler held in standby condition or in cases where dry storage is not practical.
The possibility of freezing temperatures must be considered. Care must again be taken to protect metal surfaces.
Variables preclude definite recommendations. However, it is suggested that the pressure vessel be drained, thor-
oughly cleaned internally, and re-filled to overflowing with treated water. If deaerated water is not available, the unit
should be fired to boil the water for a short period. Additional chemicals may be suggested by your local Cleaver-
Brooks authorized representative to minimize corrosion. Internal water pressure should be maintained at greater
than atmospheric pressure. Nitrogen is often used to pressurize the vessel.
Summary of Contents for 4WI
Page 46: ...Burner Operation and Control 2 22 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
Page 62: ...Waterside Care and Requirements 3 16 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
Page 70: ...Sequence of Operation 4 8 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
Page 114: ...Adjustment Procedures 6 28 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
