8 Ill. Adm. Code 215.90
Refrigerated Storage
Section 215.90 Refrigerated
Storage
a) This Section
applies specifically to systems using tanks for storage of anhydrous ammonia
under refrigerated conditions. Section 215.25 applies to this Section unless
otherwise stated.
b) Tanks
may be designed for any storage pressure desired as determined by economical
design of the refrigerated system.
c) The
design temperature shall be the minimum temperature to which the container will
be refrigerated and shall be so designated.
d) Containers
with a design pressure exceeding 15 psig shall be constructed in accordance
with Section 215.25 and the material shall be selected from those listed in API
Standard 620, Design and Construction of Large, Welded, Low-Pressure Storage
Tanks, Tables 2.02, R.2.2, R.2.3, or R.2.4.
e) Tanks
with a design pressure of 15 psig or less shall be constructed in accordance
with the general requirements of API Standard 620, including Appendix R.
f) When
austenitic stainless steels or nonferrous metals are used, the ASME Code shall
be used as a guide in selection of materials for use at the design temperature.
g) Tanks
shall be supported on suitable noncombustible foundations designed to
accommodate the type of tank being used.
h) Adequate
protection against flotation or other water damage shall be provided wherever
high flood water might occur.
i) Tanks
storing product at less than 32°F shall be supported in such a way, or heat
shall be supplied, to prevent the effects of freezing and subsequent frost
heaving of the soil.
j) The
area surrounding a refrigerated tank, or group of such tanks, shall be provided
with drainage, diked, or provided with other secondary containment systems to
prevent accidental discharge of liquid from spreading to uncontrolled areas.
k) When
drainage is employed, a slope of not less than 1% shall be provided. The
drainage system shall terminate in an impounding basin having a capacity as
large as the largest tank served.
l) Provision
shall be made for the drainage of rain water from the dike or impounding area.
Such drainage shall be provided with a positive means to stop the flow.
m) Where
a dike is employed, the capacity of the diked enclosure shall be 110% of the
capacity of the largest tank served. When computing the volume of the dike,
allowance shall be made for the volume displaced by all other containers in the
diked area.
n) The
walls of a diked enclosure or the wall of an impounding basin used in a
drainage system shall be of earth, steel, concrete, or other suitable material
designed to be liquid tight and to withstand the hydrostatic pressure and
temperature. Earth walls shall have a flat top at least 2 feet wide. The
slope shall be stable and consistent with the angle of repose of the earth
used.
o) The
ground in an impounding basin or with a diked enclosure should be graded so that
small spills or the early part of a large spill will accumulate at one side or
corner, thereby contacting only a relatively small area of ground and exposing
a relatively small area for heat gain. Shallow channels in the ground surface
or low curbs of earth can help guide the liquid to these low areas without
contacting a large ground area.
p) Each
refrigerated container shall be marked with a nameplate on the outer covering
in an accessible place as specified in the following:
1) With
the name and address of the builder and the date of fabrication;
2) With
the maximum volume or weight of the product, whichever is most meaningful to
the user;
3) With
the design pressure;
4) With
the minimum temperatures in degrees Fahrenheit (°F) or degrees Celsius (°C) for
which the container was designed;
5) With
the maximum allowable water level to which the container may be filled for the
test purposes;
6) With
the density of the product in pounds per cubic foot or kilograms per cubic
meter for which the container was designed; and
7) With
the maximum level to which the container may be filled with liquid anhydrous
ammonia.
q) Each
refrigerated container shall be marked on two directly opposite sides at near
eye level with the words ANHYDROUS AMMONIA or CAUTION – AMMONIA in sharply
contrasting colors with letters not less than 4.0 inches high.
r) Each
refrigerated container shall be conspicuously marked with a hazard warning
label complying with 29 CFR 1910.1200.
s) Shutoff valves shall be:
1) Provided
for all connections except those with a No. 54 (0.055 inches) drill size
restriction, plugs, pressure relief valves, and thermometer wells; and
2) Located
as close to the tank as practical.
t) A
check valve shall be installed on the tank liquid fill connection if it is
located below the maximum liquid level. A remotely operated shutoff valve shall
be installed on other connections located below the maximum liquid level. See
Section 215.65.
u) Each
refrigerated container shall be equipped with an approved liquid level gauging
device and high liquid level alarm.
v) The
tank shall be provided with a system of one or more pressure relief valves that
can limit the tank pressure below 115% (110% if only one pressure relief valve
is used) of the design pressure during operational emergency conditions other
than fire and below 121% of the design pressure during operational emergency
conditions that include fire. One of the pressure relief valves shall be set
to start to discharge at a pressure not in excess of the design pressure of the
tank, and all other pressure relief valves needed to limit the tank pressure
below 115% (110% if only one pressure relief valve is used) of the design
pressure during operational emergency conditions other than fire shall be set
to discharge at a pressure not in excess of 105% of the design pressure. All
additional pressure relief valves needed to limit the tank pressure below 121%
of the design pressure during operational emergency conditions, including fire,
shall be set to start to discharge at a pressure not in excess of 110% of the
design pressure.
w) The
pressure relief valve set to discharge below 105% of the design pressure of the
tank shall have a total relieving capacity in excess of the relieving capacity
required to handle operating emergency conditions listed in subsection (x).
The total relieving capacity of all the pressure relief valves in the system
shall be the larger requirement of subsection (x) or (y).
x) Possible
refrigeration system upsets are cooling water failure; power failure;
instrument air or instrument failure; mechanical failure of any equipment;
excessive pumping rates; and changing atmospheric conditions.
y) Use
either of the following formulas for fire exposure. Relief valve sizing for
fire protection may be adjusted to protect against the worst possible fire
exposure.
1) For
valve manufacturers who classify valves on the basis of the weight of the
vapors to be relieved:
■
■
2) For
valve manufacturers who classify valves on the basis of air flow:
3) Where:
W
=
weight of vapors to be relieved in pounds/hour at
relieving conditions
Qa
=
air flow in cubic feet per minute at standard conditions
60°F and 14.7 psi
F
=
fireproofing credit. Use F = 1.0 except when an approved
fireproofing material of recommended thickness is used, in which case use F =
0.2
A
=
total surface area in square feet up to 25 feet above
grade or to the equator of a sphere, whichever is greater
Z
=
compressibility factor of ammonia at relieving condition
(if not known, use Z = 1.0)
T
=
temperature in degrees R (460 + temperature in °F of gas
at relieving conditions)
M
=
molecular weight = 17 for ammonia
L
=
latent heat of ammonia at relieving conditions in Btu per
pound
C
=
constant based on relation of specific heats (C may be
obtained from the following table)
(If K is not known, use C =
315)
K
C
K
C
K
C
1.00
315
1.26
343
1.52
366
1.02
318
1.28
345
1.54
368
1.04
320
1.30
347
1.56
369
1.06
322
1.32
349
1.58
371
1.08
324
1.34
351
1.60
372
1.10
327
1.36
352
1.62
374
1.12
329
1.38
354
1.64
376
1.14
331
1.40
356
1.66
377
1.16
333
1.42
358
1.68
379
1.18
335
1.44
359
1.70
380
1.20
337
1.46
361
2.00
400
1.22
339
1.48
363
2.20
412
1.24
341
1.50
364
4) Where
K
=
Cp at atmospheric
conditions
Cv
Cp
=
specific heat of vapor at constant pressure
Cv
=
specific heat of vapor at constant volume
z) Shutoff
valves of adequate flow capacity may be provided and used to facilitate
inspection and repair of pressure relief valves. When a shutoff valve is
provided, it shall be so arranged that it can be locked or sealed open, and it
shall not be closed except by an authorized person who shall remain stationed
there while the valve remains closed and who shall again lock or seal the valve
open when leaving the station.
aa) Pressure relief valves
shall comply with the following:
1) If
stacks are used they shall be suitably designed to prevent obstruction by rain,
snow, ice, or condensate.
2) The
outlet size shall not be smaller than the nominal size of the pressure relief
valve outlet connection.
bb) Discharge
lines may be used if desired. Multiple pressure relief valves on the same
storage unit may be run into a common discharge header. The discharge line and
header shall be designed to accommodate the maximum flow and a back pressure
not exceeding 10% of the design pressure of the storage container. This back
pressure shall be included to limit total tank pressure below 121% of the
design pressure given in subsection (v). No other container or system shall
exhaust into this discharge line or header. The vent lines shall be installed
to prevent accumulation of liquid in the lines.
cc) The
discharge from pressure relief valves shall be vented away from the container,
upward and unobstructed to the open air to an area such that persons, property,
and the environment will not be harmed. All pressure relief valves shall have
suitable rain caps that will allow free discharge of the vapor and prevent the
entrance of water. Suitable provision shall be made for draining condensate
that may accumulate.
dd) Atmospheric
storage shall be provided with vacuum breakers of adequate capacity to respond
to anticipated rates of liquid withdrawal and to rapid atmospheric changes so
as to avoid damage to the container. Ammonia gas may be used to provide a pad.
ee) Pressure
relief valves used to protect other systems at refrigerated storage
installations shall discharge to the open air unless connected to a control
device as defined in Section 215.55.
ff) Because
emergency venting for a double-wall refrigerated storage tank is complex, no
calculation method is presented here. A thorough analysis of the fire relief
for a double-wall refrigerated storage tank should be conducted.
gg) Refrigerated
storage containers and appurtenances shall comply with the provisions of
Section 215.40.
hh) Containers
of such size as to require a field fabrication shall, when moved and
reinstalled, be reconstructed and re-inspected in complete accordance with the
original requirements under which they were constructed. The containers shall
be subjected to a pressure retest, and if re-rating is necessary, it shall be
done in accordance with the applicable pressure of the original requirements.
ii) The
total refrigeration load shall be computed as the sum of the following:
1) Load
imposed by heat flow into the container caused by the temperature differential
between the ambient temperature and the storage temperature;
2) Load
imposed by heat flow into the tank caused by maximum sun radiation; and
3) Maximum
load imposed by filling the tank with ammonia warmer than the design storage
temperature.
jj) More than one storage
tank may be handled by the same refrigeration system.
kk) A
minimum of two compressors shall be provided, either of which is of sufficient
size to handle the loads listed in subsections (ii)(1) and (ii)(2), except as
provided in subsection (mm). Where more than two compressors are provided,
minimum standby equipment equal to the largest normally operating equipment
shall be installed. Compressors required for subsection (ii)(3) may be used as
standby equipment for compressors required in subsections (ii)(1) and (ii)(2).
ll) Compressors
shall be sized to operate with a suction pressure at least 10% below the
minimum setting of the pressure relief valves on the storage tank and shall
withstand a suction pressure at least equal to 121% of the design pressure of
the tank. Discharge pressure will be governed by condensing conditions.
mm) Where
facilities are provided to safely dispose of vented vapor to an automatic flare
or to a process unit, a single compressor of sufficient size to handle the load
listed in subsections (ii)(1) and (ii)(2) shall be allowed.
nn) Each compressor shall have
its own drive unit.
oo) Any standard drive
consistent with good design may be used.
pp) An
emergency source of power of sufficient capacity to handle the loads listed in subsections
(ii)(1) and (ii)(2) shall be provided unless facilities are provided to safely
dispose of vented vapors while the refrigeration system is not operating.
qq) The
refrigeration system shall be arranged with suitable controls to govern the
compressor operation in accordance with the load as evidenced by the pressure
in the containers.
rr) An
emergency alarm system shall be installed to function in the event the pressure
in the containers rises to the maximum or falls to the minimum allowable
operating pressure.
ss) An
emergency alarm and shutoff shall be located in the condenser system to respond
to excess discharge pressure caused by failure of the cooling medium.
tt) All
automatic controls shall be installed in a manner to preclude operation of
alternate compressors unless the controls will function with the alternate
compressors.
uu) An
entrainment separator of suitable size and design pressure shall be installed
in the compressor suction line. The separator shall be equipped with a drain
and gauging device. A maximum liquid level control with alarm should be
installed.
vv) An oil
separator of suitable size shall be installed in the compressor discharge
line. It shall be designed for at least 250 psig and shall be equipped with a
gauging device and drain valve. A maximum oil level control with alarm should
be installed.
ww) A
separator shall be equipped with a pressure relief valve if the separator can
be isolated with shutoff valves.
xx) The
condenser system may be cooled by air or water or both. The condenser shall be
designed for at least 250 psig. Provision shall be made for purging
noncondensibles either manually or automatically.
yy) The
condenser shall be equipped with a pressure relief valve if the condenser can
be isolated with shutoff valves.
zz) A
condenser effluent receiver shall be provided that is equipped with automatic
level controls and valving designed to discharge the liquid ammonia to storage,
or with a high-pressure liquid drain trap of suitable capacity. The receiver
shall be designed for at least 250 psig operating pressure and be equipped with
the necessary connections, pressure relief valves, and gauging device.
aaa) Refrigerated
containers and pipeline that are insulated shall be covered with a material of
suitable quality and thickness for the temperatures encountered. Insulation
shall be suitably supported and protected against the weather. Weatherproofing
and insulation shall be of a type that will not support flame propagation and
will not cause corrosion when wet.
bbb) Each
refrigerated storage installation shall have on hand the minimum safety equipment
required in Section 215.20.
ccc) In
addition to the safety equipment requirement in Section 215.20, each
refrigerated storage installation shall have on hand at least two independently
supplied, positive-pressure SCBAs and at least two approved encapsulating
corrosive chemical suits that are impervious to ammonia. Each shall be
designed to accommodate an SCBA.
ddd) A sign
with letters of a minimum height of two inches giving the name and telephone
number, including area code, of owner, manager or agent of the anhydrous
ammonia storage location shall appear at the site entrances to the property or
apart from the storage tanks.