1998 Edition
Chapter 6 Water Storage Tanks 6-1 General.
6-1.1 This chapter provides the minimum requirements for
the routine inspection, testing, and maintenance of water stor- age tanks. Table 6-1.1 shall be used to determine the mini-
mum required frequencies for inspection, testing, and maintenance.
Exception: Valves and fire department connections shall be inspect-
ed, tested, and maintained in accordance with Chapter 9.
6-1.2 Impairments. The inspection, testing, and maintenance
of water storage tanks can involve or result in a system that is out of service. The procedures outlined in Chapter 11 shall be fol-
lowed where such an impairment to protection occurs.
6-1.3 Notification to Supervisory Service. To avoid false alarms
where a supervisory service is provided, the alarm receiving facil- ity always shall be notified by the owner or designated represen-
tative as follows: a Before conducting any test or procedure that could
result in the activation of an alarm b After such tests or procedures are concluded
6-2 Inspection. 6-2.1
The water level and the condition of the water in the tank shall be inspected monthly.
Exception: Tanks equipped with supervised water level alarms that
are connected to a constantly attended location shall be permitted to be inspected quarterly.
6-2.2 The exterior of the tank, supporting structure, vents,
foundation, condition of the water in the tank, and catwalks or ladders, where provided, shall be inspected quarterly for signs
of obvious damage or weakening.
6-2.3 The area surrounding the tank and supporting struc-
ture, where provided, shall be inspected quarterly to ensure that the following conditions are met:
a The area is free of combustible storage, trash, debris, brush, or material that could present a fire exposure hazard.
b The area is free of the accumulation of material on or near parts that could result in accelerated corrosion or rot.
c The tank and support are free of ice buildup. d The exterior sides and top of similar walls are free of ero-
sion embankment-supported, coated-fabric tanks only.
6-2.4 The interior of the tank shall be inspected every 5 years.
Exception No. 1: The interior of steel tanks without corrosion protec-
tion shall be inspected every 3 years. Exception No. 2:
The interior of pressure tanks shall be inspected ev- ery 3 years.
6-2.4.1 The interior inspection of the tank shall include the
following: a The interior coating shall be inspected for signs of local
or general failure. b Center columns of tubular design shall be inspected to
make sure they are not holding water. c Center columns shall be inspected to ensure that they
are not permanently attached to the floor. d Tanks on ring-type foundations with sand in the middle
shall be inspected for voids beneath the floor. Such voids shall be filled by pumping in grout or accessing the sand
and replenishing. e The heating system and components including piping
shall be inspected. Damaged components and corroded pipe shall be replaced.
f The anti-vortex plate shall be inspected.
6-2.5 The hoops and grillage of wooden tanks shall be
inspected annually.
6-2.6 Exterior painted, coated, or insulated surfaces of the
tank and supporting structure, where provided, shall be inspected annually for signs of degradation.
6-2.7 The air pressure in pressure tanks shall be inspected
monthly. Exception:
Pressure tanks that have their air pressure source super- vised in accordance with NFPA 72, National Fire Alarm Code
®
, shall be permitted to be inspected quarterly.
6-2.8 The heating system, where provided, shall be inspected
daily during the heating season. Exception:
Tank heating systems installed on tanks equipped with a supervised low water temperature alarm that are connected to a con-
stantly attended location shall be permitted to be inspected weekly.
6. Electrical System a General inspection
X Weekly
b Tighten control and power wiring connections
X Annually
c Wire chafing where subject to movement
X X
Quarterly d Operation of safeties and alarms
X X
Semiannually e Boxes, panels, and cabinets
X Semiannually
f Circuit breakers or fuses
X X
Monthly g Circuit breakers or fuses
X Biannually
Table 5-5.1 Summary of Fire Pump Inspection, Testing, and Maintenance Continued Complete as Applicable
Visual Inspection
Check Change
Clean Test
Frequency
1998 Edition
6-2.9 Where the tank is subject to freezing, the water temper-
ature shall be inspected daily. The coldest water temperature shall not be less than 40°F 4°C.
Exception: Tanks equipped with low water temperature alarms that
are connected to a constantly attended location shall be permitted to be inspected weekly and have the results recorded weekly.
6-2.10 Expansion joints, where provided, shall be inspected
annually for leaks and cracks.
6-3 Testing. 6-3.1
Level indicators shall be tested every 5 years for accu- racy and freedom of movement.
6-3.2 The tank heating system, where provided, shall be tested
prior to the heating season to make certain it is in the proper working order.
6-3.3 Low water temperature alarms, where provided, shall be
tested monthly cold weather only.
6-3.4 High water temperature limit switches on tank heating
systems, where provided, shall be tested monthly whenever the heating system is in service.
6-3.5
High and low water level alarms shall be tested semian- nually.
6-3.6 Pressure gauges shall be tested every 5 years with a cal-
ibrated gauge in accordance with the manufacturer’s instruc- tions. Gauges not accurate to within 3 percent of the scale of
the gauge being tested shall be recalibrated or replaced.
6-3.7 During the interior inspection outlined in 6-2.4, the fol-
lowing tests shall also be performed: a Evaluation of tank coatings in accordance with the adhe-
sion test of ASTM D 3359, generally referred to as the “cross-hatch test.”
b Dry film thickness measurements shall be taken at ran- dom locations to determine the overall coating thickness.
c Nondestructive ultrasonic readings shall be taken to evaluate the wall thickness where there is evidence of pit-
ting or corrosion.
Table 6-1.1 Summary of Water Storage Tank Inspection, Testing, and Maintenance Item
Activity Frequency
Reference
Condition of water in tank Inspection
Monthlyquarterly 6-2.1
Water temperature Inspection
Dailyweekly 6-2.9
Heating system Inspection
Dailyweekly 6-2.8
Control valves Inspection
Weeklymonthly Table 9-1
Water — level Inspection
Monthlyquarterly 6-2.1
Air pressure Inspection
Monthlyquarterly 6-2.7
Tank — exterior Inspection
Quarterly 6-2.2
Support structure Inspection
Quarterly 6-2.2
Catwalks and ladders Inspection
Quarterly 6-2.2
Surrounding area Inspection
Quarterly 6-2.3
Hoops and grillage Inspection
Annually 6-2.5
Paintedcoated surfaces Inspection
Annually 6-2.6
Expansion joints Inspection
Annually 6-2.10
Interior Inspection
5 years3 years 6-2.4
Check valves Inspection
5 years Table 9-1
Temperature alarms Test
Monthly 6-3.3
High-temperature limit switches Test
Monthly 6-3.4
Water level alarms Test
Semiannually 6-3.5
Level indicators Test
5 years 6-3.1
Pressure gauges Test
5 years 6-3.6
Water level Maintenance
— 6-4.1
Thermostats Maintenance
— 6-4.7
Drain sediment Maintenance
Semiannually 6-4.3
Cathodic protection Maintenance
Annually 6-4.5
Drain valves cycled Maintenance
Annually 6-4.8
Vent screens Maintenance
Annually 6-4.9
Control valves Maintenance
Annually Table 9-1
Repainting — steel Maintenance
— 6-4.16
Embankment-supported coated- fabric ESCF
Maintenance —
6-4.17 Check valves
Maintenance —
9-4.2.2 Cold weatherheating season only.
1998 Edition
d Interior surfaces shall be spot wet-sponge tested to detect pinholes, cracks, or other compromises in the
coating. Special attention shall be given to sharp edges such as ladder rungs, nuts, and bolts.
e Tank bottoms shall be tested for metal loss andor rust on the underside by use of ultrasonic testing where there
is evidence of pitting or corrosion. Exception to e: Removal, visual inspection, and replacement of ran-
dom floor coupons shall be an acceptable alternative to ultrasonic test- ing.
f Tanks with flat bottoms shall be vacuum-box tested at bottom seams in accordance with test procedures found
in NFPA 22, Standard for Water Tanks for Private Fire Protec- tion.
6-4 Maintenance. 6-4.1
The tank shall be maintained full or at the designed water level. The hatch covers in the roofs and the door at the
top of the frostproof casing shall always be kept securely fas- tened with substantial catches as a protection against freezing
and windstorm damage.
6-4.2 The interior and exterior of any tank, along with the
supporting structure, where provided, shall be maintained free of peeling paint, aquatic growth, sediment, foreign mat-
ter, tools, painting equipment, or any other material that could interfere with proper operation of the tank. Ice that can
cause functional deficiencies to system performance shall not be allowed to collect in or on any part of the tank or structure.
6-4.3 Sediment shall be drained or flushed from the tank
semiannually.
6-4.4 The tank and supporting structure, where provided,
shall be protected from rot, corrosion, rust, mechanical dam- age, accumulation debris, and sediment. The tops of founda-
tion piers shall be maintained at least 6 in. 152 mm above ground level. Combustible material shall not be permitted
near the columns.
6-4.5
Cathodic protection, where provided, shall be main- tained annually in accordance with the manufacturer’s
instructions.
6-4.6 Pipe and supports shall be maintained in accordance
with the rules for sprinkler pipe and supports in Chapter 2.
6-4.7 Tank thermometers shall be maintained in accordance
with the manufacturer’s instructions.
6-4.8 All tank drain valves shall be opened fully and closed
annually.
6-4.9 Tank vents shall be cleaned at least annually or more fre-
quently as necessary. Mesh screens shall be replaced when cleaning or inspection see 6-2.2 reveals holes. See NFPA 22,
Standard for Water Tanks for Private Fire Protection, for appropriate materials.
6-4.10 Valve pits and valve or heater houses shall be main-
tained at a minimum temperature of 40°F 4°C, weathertight, and free of water accumulations.
6-4.11 Tank heating systems shall be maintained in accor-
dance with the manufacturer’s instructions. The coldest water in the tank shall not be less than 40°F 4°C.
6-4.12 Repair work and replacement parts shall meet the orig-
inal design criteria and the installation requirements of NFPA 22, Standard for Water Tanks for Private Fire Protection.
6-4.13 Repairs to the tank shall be made only with materials
that cannot become loose or dislodged and obstruct the out- let.
6-4.14 All welding performed on the tank shall be completed
and tested in accordance with AWWA D100 AWS D5.2, Stan- dard for Welded Steel Tanks for Water Storage.
6-4.15 During interior tank maintenance and painting activi-
ties, a protective cover of no more than a few sheets of paper shall be used to cover the outlet opening. This protective cov-
ering shall be removed prior to returning the tank to service.
6-4.16 Repainting of Steel Tanks. Repainting shall be done
only on dry surfaces that are thoroughly cleaned of all base paint, rust, scale, or other surface contamination.
6-4.17 Maintenance of Embankment-Supported Coated Fab- ric ESCF Suction Tanks.
The maintenance of ESCF tanks shall be completed in accordance with this section and the
tank manufacturer’s instructions.
6-4.17.1 No waste materials, such as boards, paint cans, trim
or loose material, shall be left in the tank or on the surface of the tank.
6-4.17.2 The access fittings in the top of the tank shall be
kept securely fastened as a protection against freezing and windstorm damage.
6-4.17.3 Large accumulations of ice shall not be allowed to
collect on the top of the tank. This can be overcome by main- taining the temperature of the water above freezing and keep-
ing the tank filled to capacity.
6-4.17.4 Combustible material of any kind shall not be permit-
ted near the tank, and the site shall be kept clear of weeds, brush, and dead foliage.
6-4.17.5 The exposed surfaces of the tank shall be inspected
for painting every two years, and the interior of the tank shall be cleaned and inspected as required to eliminate a buildup
of sediment.
6-4.17.6
A paint recommended by the manufacturer shall be used to refurbish the top surface of the tank. A procedure rec-
ommended by the manufacturer shall be used to refurbish the top surface of the tank.
6-4.17.7 The surfaces of the embankment and the berm shall
be inspected for soil erosion.
6-5 Records. Records shall be maintained in accordance with
Section 1-8.
Chapter 7 Water Spray Fixed Systems 7-1 General.
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