[Code of Federal Regulations]
[Title 29, Volume 5]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 29CFR1910.111]
[Page 333-347]
TITLE 29--LABOR
CHAPTER XVII--OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT
OF LABOR
PART 1910_OCCUPATIONAL SAFETY AND HEALTH STANDARDS--Table of Contents
Subpart H_Hazardous Materials
Sec. 1910.111 Storage and handling of anhydrous ammonia.
(a) General--(1) Scope. (i) This standard is intended to apply to
the design, construction, location, installation, and operation of
anhydrous ammonia systems including refrigerated ammonia storage
systems.
(ii) This standard does not apply to:
(a) Ammonia manufacturing plants.
(b) Refrigeration plants where ammonia is used solely as a
refrigerant.
(2) Definitions. As used in this section.
(i) Appurtenances. All devices such as pumps, compressors, safety
relief devices, liquid-level gaging devices, valves and pressure gages.
(ii) Cylinder. A container of 1,000 pounds of water capacity or less
constructed in accordance with Department of Transportation
specifications.
(iii) Code. The Boiler and Pressure Vessel Code, Section VIII,
Unfired Pressure Vessels of the American Society of Mechanical Engineers
(ASME)--1968.
(iv) Container. Includes all vessels, tanks, cylinders, or spheres
used for transportation, storage, or application of anhydrous ammonia.
(v) DOT. U.S. Department of Transportation.
(vi) Design pressure is identical to the term Maximum Allowable
Working Pressure used in the Code.
(vii) Farm vehicle (implement of husbandry). A vehicle for use on a
farm on which is mounted a container of not over 1,200 gallons water
capacity.
(viii) Filling density. the percent ratio of the weight of the gas
in a container to the weight of water at 60 [deg]F. that the container
will hold.
(ix) Gas. Anhydrous ammonia in either the gaseous or liquefied
state.
(x) Gas masks. Gas masks must be approved by the National Institute
for Occupational Safety and Health (NIOSH) under 42 CFR part 84 for use
with anhydrous ammonia.
(xi) Capacity. Total volume of the container in standard U.S.
gallons.
(xii) DOT specifications--Regulations of the Department of
Transportation published in 49 CFR Chapter I.
(b) Basic rules. This paragraph applies to all paragraphs of this
section unless otherwise noted.
[[Page 334]]
(1) Approval of equipment and systems. Each appurtenance shall be
approved in accordance with paragraph (b)(1) (i), (ii), (iii), or (iv)
of this section.
(i) It was installed before February 8, 1973, and was approved,
tested, and installed in accordance with either the provisions of the
American National Standard for the Storage and Handling of Anhydrous
Ammonia, K61.1, or the Fertilizer Institute Standards for the Storage
and Handling of Agricultural Anhydrous Ammonia, M-1, (both of which are
incorporated by reference as specified in Sec. 1910.6) in effect at the
time of installation; or
(ii) It is accepted, or certified, or listed, or labeled, or
otherwise determined to be safe by a nationally recognized testing
laboratory; or
(iii) It is a type which no nationally recognized testing laboratory
does, or will undertake to, accept, certify, list, label, or determine
to be safe; and such equipment is inspected or tested by any Federal,
State, municipal, or other local authority responsible for enforcing
occupational safety provisions of a Federal, State, municipal or other
local law, code, or regulation pertaining to the storage, handling,
transport, and use of anhydrous ammonia, and found to be in compliance
with either the provisions of the American National Standard for the
Storage and Handling of Anhydrous Ammonia, K61.1, or the Fertilizer
Institute Standards for the Storage and Handling of Agricultural
Anhydrous Ammonia, M-1, in effect at the time of installation; or
(iv) It is a custom-designed and custom-built unit, which no
nationally recognized testing laboratory, or Federal, State, municipal
or local authority responsible for the enforcement of a Federal, State,
municipal, or local law, code or regulation pertaining to the storage,
transportation and use of anhydrous ammonia is willing to undertake to
accept, certify, list, label or determine to be safe, and the employer
has on file a document attesting to its safe condition following the
conduct of appropriate tests. The document shall be signed by a
registered professional engineer or other person having special training
or experience sufficient to permit him to form an opinion as to safety
of the unit involved. The document shall set forth the test bases, test
data and results, and also the qualifications of the certifying person.
(v) For the purposes of this paragraph (b)(1), the word listed means
that equipment is of a kind mentioned in a list which is published by a
nationally recognized laboratory which makes periodic inspection of the
production of such equipment, and states such equipment meets nationally
recognized standards or has been tested and found safe for use in a
specified manner. Labeled means there is attached to it a label, symbol,
or other identifying mark of a nationally recognized testing laboratory
which, makes periodic inspections of the production of such equipment,
and whose labeling indicates compliance with nationally recognized
standards or tests to determine safe use in a specified manner.
Certified means it has been tested and found by a nationally recognized
testing laboratory to meet nationally recognized standards or to be safe
for use in a specified manner, or is of a kind whose production is
periodically inspected by a nationally recognized testing laboratory,
and it bears a label, tag, or other record of certification.
(vi) For the purposes of this paragraph (b)(1), refer to Sec.
1910.7 for definition of nationally recognized testing laboratory.
(2) Requirements for construction, original test and requalification
of nonrefrigerated containers. (i) Containers used with systems covered
in paragraphs (c), (f), (g), and (h) of this section shall be
constructed and tested in accordance with the Code except that
construction under Table UW12 at a basic joint efficiency of under 80
percent is not authorized.
(ii) Containers built according to the Code do not have to comply
with Paragraphs UG125 to UG128 inclusive, and Paragraphs UG132 and UG133
of the Code.
(iii) Containers exceeding 36 inches in diameter or 250 gallons
water capacity shall be constructed to comply with one or more of the
following:
(a) Containers shall be stress relieved after fabrication in
accordance with the Code, or
[[Page 335]]
(b) Cold-form heads when used, shall be stress relieved, or
(c) Hot-formed heads shall be used.
(iv) Welding to the shell, head, or any other part of the container
subject to internal pressure shall be done in compliance with the Code.
Other welding is permitted only on saddle plates, lugs, or brackets
attached to the container by the container manufacturer.
(v) Containers used with systems covered in paragraph (e) of this
section shall be constructed and tested in accordance with the DOT
specifications.
(vi) The provisions of subdivision (i) of this subparagraph shall
not be construed as prohibiting the continued use or reinstallation of
containers constructed and maintained in accordance with the 1949, 1950,
1952, 1956, 1959, and 1962 editions of the Code or any revisions thereof
in effect at the time of fabrication.
(3) Marking nonrefrigerated containers. (i) System nameplates, when
required, shall be permanently attached to the system so as to be
readily accessible for inspection and shall include markings as
prescribed in subdivision (ii) of this subparagraph.
(ii) Each container or system covered in paragraphs (c), (f), (g),
and (h) of this section shall be marked as specified in the following:
(a) With a notation ``Anhydrous Ammonia.''
(b) With a marking identifying compliance with the rules of the Code
under which the container is constructed.
Under ground: Container and system nameplate.
Above ground: Container.
(c) With a notation whether the system is designed for underground
or aboveground installation or both.
(d) With the name and address of the supplier of the system or the
trade name of the system and with the date of fabrication.
Under ground and above ground: System nameplate.
(e) With the water capacity of the container in pounds at 60 [deg]F.
or gallons, U.S. Standard.
Under ground: Container and system nameplate.
Above ground: Container.
(f) With the design pressure in pounds per square inch.
Under ground: Container and system nameplate.
Above ground: Container.
(g) With the wall thickness of the shell and heads.
Under ground: Container and system nameplate.
Above ground: Container.
(h) With marking indicating the maximum level to which the container
may be filled with liquid anhydrous ammonia at temperatures between 20
[deg]F. and 130 [deg]F. except on containers provided with fixed level
indicators, such as fixed length dip tubes, or containers that are
filled with weight. Markings shall be in increments of not more than 20
[deg]F.
Above ground and under ground: System nameplate or on liquid-level
gaging device.
(i) With the total outside surface area of the container in square
feet.
Under ground: System nameplate.
Above ground: No requirement.
(j) Marking specified on the container shall be on the container
itself or on a nameplate permanently attached to it.
(4) Marking refrigerated containers. Each refrigerated container
shall be marked with nameplate on the outer covering in an accessible
place as specified in the following:
(i) With the notation, ``Anhydrous Ammonia.''
(ii) With the name and address of the builder and the date of
fabrication.
(iii) With the water capacity of the container in gallons, U.S.
Standard.
(iv) With the design pressure.
(v) With the minimum temperature in degrees Fahrenheit for which the
container was designed.
(vi) The maximum allowable water level to which the container may be
filled for test purposes.
(vii) With the density of the product in pounds per cubic foot for
which the container was designed.
(viii) With the maximum level to which the container may be filled
with liquid anhydrous ammonia.
[[Page 336]]
(5) Location of containers. (i) Consideration shall be given to the
physiological effects of ammonia as well as to adjacent fire hazards in
selecting the location for a storage container. Containers shall be
located outside of buildings or in buildings or sections thereof
especially provided for this purpose.
(ii) Permanent storage containers shall be located at least 50 feet
from a dug well or other sources of potable water supply, unless the
container is a part of a water-treatment installation.
(iii)-(iv) [Reserved]
(v) Storage areas shall be kept free of readily ignitible materials
such as waste, weeds, and long dry grass.
(6) Container appurtenances. (i) All appurtenances shall be designed
for not less than the maximum working pressure of that portion of the
system on which they are installed. All appurtenances shall be
fabricated from materials proved suitable for anhydrous ammonia service.
(ii) All connections to containers except safety relief devices,
gaging devices, or those fitted with No. 54 drill-size orifice shall
have shutoff valves located as close to the container as practicable.
(iii) Excess flow valves where required by these standards shall
close automatically at the rated flows of vapor or liquid as specified
by the manufacturer. The connections and line including valves and
fittings being protected by an excess flow valve shall have a greater
capacity than the rated flow of the excess flow valve so that the valve
will close in case of failure of the line or fittings.
(iv) Liquid-level gaging devices that require bleeding of the
product to the atmosphere and which are so constructed that outward flow
will not exceed that passed by a No. 54 drill-size opening need not be
equipped with excess flow valves.
(v) Openings from the container or through fittings attached
directly on the container to which pressure gage connections are made
need not be equipped with excess flow valves if such openings are not
larger than No. 54 drill size.
(vi) Excess flow and back pressure check valves where required by
the standards in this section shall be located inside of the container
or at a point outside as close as practicable to where the line enters
the container. In the latter case installation shall be made in such
manner that any undue strain beyond the excess flow or back pressure
check valve will not cause breakage between the container and the valve.
(vii) Excess flow valves shall be designed with a bypass, not to
exceed a No. 60 drill-size opening to allow equalization of pressures.
(viii) All excess flow valves shall be plainly and permanently
marked with the name or trademark of the manufacturer, the catalog
number, and the rated capacity.
(7) Piping, tubing, and fittings. (i) All piping, tubing, and
fittings shall be made of material suitable for anhydrous ammonia
service.
(ii) All piping, tubing, and fittings shall be designed for a
pressure not less than the maximum pressure to which they may be
subjected in service.
(iii) All refrigerated piping shall conform to the Refrigeration
Piping Code, American National Standards Institute, B31.5-1966 with
addenda B31.1a-1968, which is incorporated by reference as specified in
Sec. 1910.6, as it applies to ammonia.
(iv) Piping used on non-refrigerated systems shall be at least
American Society for Testing and Materials (ASTM) A-53-69 Grade B
Electric Resistance Welded and Electric Flash Welded Pipe, which is
incorporated by reference as specified in Sec. 1910.6, or equal. Such
pipe shall be at least schedule 40 when joints are welded, or welded and
flanged. Such pipe shall be at least schedule 80 when joints are
threaded. Threaded connections shall not be back-welded. Brass, copper,
or galvanized steel pipe shall not be used.
(v) Tubing made of brass, copper, or other material subject to
attack by ammonia shall not be used.
(vi) Cast iron fittings shall not be used but this shall not
prohibit the use of fittings made specifically for ammonia service of
malleable, nodular, or high strength gray iron meeting American Society
for Testing and Materials (ASTM) A47-68, ASTM 395-68, or ASTM
[[Page 337]]
A126-66 Class B or C all of which are incorporated by reference as
specified in Sec. 1910.6.
(vii) Joint compounds shall be resistant to ammonia.
(8) Hose specifications. (i) Hose used in ammonia service shall
conform to the joint Agricultural Ammonia Institute--Rubber
Manufacturers Association Specifications for Anhydrous Ammonia Hose.
(ii) Hose subject to container pressure shall be designed for a
minimum working pressure of 350 p.s.i.g. and a minimum burst pressure of
1,750 p.s.i.g. Hose assemblies, when made up, shall be capable of
withstanding a test pressure of 500 p.s.i.g.
(iii) Hose and hose connections located on the low-pressure side of
flow control of pressure-reducing valves shall be designed for a
bursting pressure of not less than 5 times the pressure setting of the
safety relief devices protecting that portion of the system but not less
than 125 p.s.i.g. All connections shall be so designed and constructed
that there will be no leakage when connected.
(iv) Where hose is to be used for transferring liquid from one
container to another, ``wet'' hose is recommended. Such hose shall be
equipped with approved shutoff valves at the discharge end. Provision
shall be made to prevent excessive pressure in the hose.
(v) On all hose one-half inch outside diameter and larger, used for
the transfer of anhydrous ammonia liquid or vapor, there shall be
etched, cast, or impressed at 5-foot intervals the following
information.
``Anhydrous Ammonia'' xxx p.s.i.g. (maximum working pressure),
manufacturer's name or trademark, year of manufacture.
In lieu of this requirement the same information may be contained on a
nameplate permanently attached to the hose.
Table H-36
[Minimum required rate of discharge in cubic feet per minute of air at
120 percent of the maximum permitted start to discharge pressure of
safety relief valves]
------------------------------------------------------------------------
Flow rate
Surface area (sq. ft.) CFM air
------------------------------------------------------------------------
20.......................................................... 258
25.......................................................... 310
30.......................................................... 360
35.......................................................... 408
40.......................................................... 455
45.......................................................... 501
50.......................................................... 547
55.......................................................... 591
60.......................................................... 635
65.......................................................... 678
70.......................................................... 720
75.......................................................... 762
80.......................................................... 804
85.......................................................... 845
90.......................................................... 885
95.......................................................... 925
100......................................................... 965
105......................................................... 1,010
110......................................................... 1,050
115......................................................... 1,090
120......................................................... 1,120
125......................................................... 1,160
130......................................................... 1,200
135......................................................... 1,240
140......................................................... 1,280
145......................................................... 1,310
150......................................................... 1,350
155......................................................... 1,390
160......................................................... 1,420
165......................................................... 1,460
170......................................................... 1,500
175......................................................... 1,530
180......................................................... 1,570
185......................................................... 1,600
190......................................................... 1,640
195......................................................... 1,670
200......................................................... 1,710
210......................................................... 1,780
220......................................................... 1,850
230......................................................... 1,920
240......................................................... 1,980
250......................................................... 2,050
260......................................................... 2,120
270......................................................... 2,180
280......................................................... 2,250
290......................................................... 2,320
300......................................................... 2,380
310......................................................... 2,450
320......................................................... 2,510
330......................................................... 2,570
340......................................................... 2,640
350......................................................... 2,700
360......................................................... 2,760
370......................................................... 2,830
380......................................................... 2,890
390......................................................... 2,950
400......................................................... 3,010
450......................................................... 3,320
500......................................................... 3,620
550......................................................... 3,910
600......................................................... 4,200
650......................................................... 4,480
700......................................................... 4,760
750......................................................... 5,040
800......................................................... 5,300
850......................................................... 5,590
900......................................................... 5,850
950......................................................... 6,120
1,000....................................................... 6,380
1,050....................................................... 6,640
[[Page 338]]
1,100....................................................... 6,900
1,150....................................................... 7,160
1,200....................................................... 7,410
1,250....................................................... 7,660
1,300....................................................... 7,910
1,350....................................................... 8,160
1,400....................................................... 8,410
1,450....................................................... 8,650
1,500....................................................... 8,900
1,550....................................................... 9,140
1,600....................................................... 9,380
1,650....................................................... 9,620
1,700....................................................... 9,860
1,750....................................................... 10,090
1,800....................................................... 10,330
1,850....................................................... 10,560
1,900....................................................... 10,800
1,950....................................................... 11,030
2,000....................................................... 11,260
2,050....................................................... 11,490
2,100....................................................... 11,720
2,150....................................................... 11,950
2,200....................................................... 12,180
2,250....................................................... 12,400
2,300....................................................... 12,630
2,350....................................................... 12,850
2,400....................................................... 13,080
2,450....................................................... 13,300
2,500....................................................... 13,520
------------------------------------------------------------------------
Surface Area=total outside surface area of container in square feet.
When the surface area is not stamped on the nameplate or when the
marking is not legible the area can be calculated by using one of the
following formulas:
(1) Cylindrical container with hemispherical heads:
Area=overall length in feet times outside diameter in feet times 3.1416.
(2) Cylindrical container with other than hemispherical heads:
Area=(overall length in feet plus 0.3 outside diameter in feet) times
outside diameter in feet times 3.1416.
(3) Spherical container:
Area=outside diameter in feet squared times 3.1416.
Flow Rate--CFM Air=cubic feet per minute of air required at standard
conditions, 60 [deg]F. and atmospheric pressure (14.7 p.s.i.a.).
The rate of discharge may be interpolated for intermediate values of
surface area. For containers with total outside surface area greater
than 2,500 square feet, the required flow rate can be calculated using
the formula: Flow Rate CFM Air=22.11 A\0 82\, where A=outside surface
area of the container in square feet.
(9) Safety relief devices. (i) Every container used in systems
covered by paragraphs (c), (f), (g), and (h) of this section shall be
provided with one or more safety relief valves of the spring-loaded or
equivalent type. The discharge from safety-relief valves shall be vented
away from the container upward and unobstructed to the atmosphere. All
relief-valve discharge openings shall have suitable rain caps that will
allow free discharge of the vapor and prevent entrance of water.
Provision shall be made for draining condensate which may accumulate.
The rate of the discharge shall be in accordance with the provisions of
Table H-36.
(ii) Container safety-relief valves shall be set to start-to-
discharge as follows, with relation to the design pressure of the
container:
------------------------------------------------------------------------
Minimum Maximum
Containers (percent) (percent)
------------------------------------------------------------------------
ASME-U-68, U-69................................. 110 125
ASME-U-200, U-201............................... 95 100
ASME 1959, 1956, 1952, or 1962.................. 95 100
API-ASME........................................ 95 100
U.S. Coast Guard................................ 95 100
------------------------------------------------------------------------
As required by DOT Regulations.
(iii) Safety relief devices used in systems covered by paragraphs
(c), (f), (g), and (h) of this section shall be constructed to discharge
at not less than the rates required in paragraph (b)(9)(i) of this
section before the pressure is in excess of 120 percent (not including
the 10 percent tolerance referred to in paragraph (b)(9)(ii) of this
section) of the maximum permitted start-to-discharge pressure setting of
the device.
(iv) Safety-relief valves shall be so arranged that the possibility
of tampering will be minimized. If the pressure setting adjustment is
external, the relief valves shall be provided with means for sealing the
adjustment.
(v) Shutoff valves shall not be installed between the safety-relief
valves and the container; except, that a shutoff valve may be used where
the arrangement of this valve is such as always to afford full required
capacity flow through the relief valves.
(vi) Safety-relief valves shall have direct communication with the
vapor space of the container.
(vii) Each container safety-relief valve used with systems covered
by paragraphs (c), (f), (g), and (h) of this
[[Page 339]]
section shall be plainly and permanently marked with the symbol
``NH<INF>3</INF>'' or ``AA''; with the pressure in pounds-per-square-
inch gage at which the valve is set to start-to-discharge; with the
actual rate of discharge of the valve at its full open position in cubic
feet per minute of air at 60 [deg]F. and atmospheric pressure; and with
the manufacturer's name and catalog number. Example: ``NH<INF>3</INF>
250-4050 Air'' indicates that the valve is suitable for use on an
anhydrous ammonia container, is set to start-to-discharge at a pressure
of 250 p.s.i.g., and that its rate of discharge at full open position
(subdivisions (ii) and (iii) of this subparagraph) is 4,050 cubic feet
per minute of air.
(viii) The flow capacity of the relief valve shall not be restricted
by any connection to it on either the upstream or downstream side.
(ix) A hydrostatic relief valve shall be installed between each pair
of valves in the liquid ammonia piping or hose where liquid may be
trapped so as to relieve into the atmosphere at a safe location.
(10) General.
(i) [Reserved]
(ii) Stationary storage installations must have at least two
suitable gas masks in readily-accessible locations. Full-face masks with
ammonia canisters that have been approved by NIOSH under 42 CFR part 84
are suitable for emergency action involving most anhydrous ammonia
leaks, particularly leaks that occur outdoors. For respiratory
protection in concentrated ammonia atmospheres, a self-contained
breathing apparatus is required.
(iii) Stationary storage installations shall have an easily
accessible shower or a 50-gallon drum of water.
(iv) Each vehicle transporting ammonia in bulk except farm
applicator vehicles shall carry a container of at least 5 gallons of
water and shall be equipped with a full face mask.
(11) Charging of containers. (i) The filling densities for
containers that are not refrigerated shall not exceed the following:
------------------------------------------------------------------------
Percent by Percent by
Type of container weight volume
------------------------------------------------------------------------
Aboveground-Uninsulated......................... 56 82
Aboveground-Uninsulated......................... .......... 87.5
Aboveground-Insulated........................... 57 83.5
Underground-Uninsulated......................... 58 85
DOT--In accord with DOT regulations.............
------------------------------------------------------------------------
(ii) Aboveground uninsulated containers may be charged 87.5 percent
by volume provided the temperature of the anhydrous ammonia being
charged is determined to be not lower than 30 [deg]F. or provided the
charging of the container is stopped at the first indication of frost or
ice formation on its outside surface and is not resumed until such frost
or ice has disappeared.
(12) Transfer of liquids. (i) Anhydrous ammonia shall always be at a
temperature suitable for the material of construction and the design of
the receiving container.
(ii) The employer shall require the continuous presence of an
attendant in the vicinity of the operation during such time as ammonia
is being transferred.
(iii) Containers shall be charged or used only upon authorization of
the owner.
(iv) Containers shall be gaged and charged only in the open
atmosphere or in buildings or areas thereof provided for that purpose.
(v) Pumps used for transferring ammonia shall be those manufactured
for that purpose.
(a) Pumps shall be designed for at least 250 p.s.i.g. working
pressure.
(b) Positive displacement pumps shall have, installed off the
discharged port, a constant differential relief valve discharging into
the suction port of the pump through a line of sufficient size to carry
the full capacity of the pump at relief valve setting, which setting and
installation shall be according to the pump manufacturer's
recommendations.
(c) On the discharge side of the pump, before the relief valve line,
there shall be installed a pressure gage graduated from 0 to 400 p.s.i.
(d) Plant piping shall contain shutoff valves located as close as
practical to pump connections.
(vi) Compressors used for transferring or refrigerating ammonia
shall be recommended for ammonia service by the manufacturer.
[[Page 340]]
(a) Compressors shall be designed for at least 250 p.s.i.g. working
pressure.
(b) Plant piping shall contain shutoff valves located as close as
practical to compressor connections.
(c) A relief valve large enough to discharge the full capacity of
the compressor shall be connected to the discharge before any shutoff
valve.
(d) Compressors shall have pressure gages at suction and discharge
graduated to at least one and one-half times the maximum pressure that
can be developed.
(e) Adequate means, such as drainable liquid trap, shall be provided
on the compressor suction to minimize the entry of liquid into the
compressor.
(vii) Loading and unloading systems shall be protected by suitable
devices to prevent emptying of the storage container or the container
being loaded or unloaded in the event of severance of the hose. Backflow
check valves or properly sized excess flow valves shall be installed
where necessary to provide such protection. In the event that such
valves are not practical, remotely operated shutoff valves may be
installed.
(13) Tank car unloading points and operations. (i) Provisions for
unloading tank cars shall conform to the applicable recommendations
contained in the DOT regulations.
(ii) The employer shall insure that unloading operations are
performed by reliable persons properly instructed and given the
authority to monitor careful compliance with all applicable procedures.
(iii) Caution signs shall be so placed on the track or car as to
give necessary warning to persons approaching the car from open end or
ends of siding and shall be left up until after the car is unloaded and
disconnected from discharge connections. Signs shall be of metal or
other suitable material, at least 12 by 15 inches in size and bear the
words ``STOP--Tank Car Connected'' or ``STOP--Men at Work'' the word,
``STOP,'' being in letters at least 4 inches high and the other words in
letters at least 2 inches high.
(iv) The track of a tank car siding shall be substantially level.
(v) Brakes shall be set and wheels blocked on all cars being
unloaded.
(14) Liquid-level gaging device. (i) Each container except those
filled by weight shall be equipped with an approved liquid-level gaging
device. A thermometer well shall be provided in all containers not
utilizing a fixed liquid-level gaging device.
(ii) All gaging devices shall be arranged so that the maximum liquid
level to which the container is filled is readily determined.
(iii) Gaging devices that require bleeding of the product to the
atmosphere such as the rotary tube, fixed tube, and slip tube devices
shall be designed so that the maximum opening of the bleed valve is not
larger than No. 54 drill size unless provided with an excess flow valve.
(This requirement does not apply to farm vehicles used for the
application of ammonia as covered in paragraph (h) of this section.)
(iv) Gaging devices shall have a design pressure equal to or greater
than the design pressure of the container on which they are installed.
(v) Fixed tube liquid-level gages shall be designed and installed to
indicate that level at which the container is filled to 85 percent of
its water capacity in gallons.
(vi) Gage glasses of the columnar type shall be restricted to
stationary storage installations. They shall be equipped with shutoff
valves having metallic handwheels, with excess-flow valves, and with
extra heavy glass adequately protected with a metal housing applied by
the gage manufacturer. They shall be shielded against the direct rays of
the sun.
(15) [Reserved]
(16) Electrical equipment and wiring. (i) Electrical equipment and
wiring for use in ammonia installations shall be general purpose or
weather resistant as appropriate.
(ii) Electrical systems shall be installed and maintained in
accordance with subpart S of this part.
(c) Systems utilizing stationary, nonrefrigerated storage
containers. This paragraph applies to stationary, nonrefrigerated
storage installations utilizing containers other than those covered in
paragraph (e) of this section. Paragraph (b) of this section applies to
this paragraph unless otherwise noted.
[[Page 341]]
(1) Design pressure and construction of containers. The minimum
design pressure for nonrefrigerated containers shall be 250 p.s.i.g.
(2) Container valves and accessories, filling and discharge
connections. (i) Each filling connection shall be provided with
combination back-pressure check valve and excess-flow valve; one double
or two single back-pressure check valves; or a positive shutoff valve in
conjunction with either an internal back-pressure check valve or an
internal excess flow valve.
(ii) All liquid and vapor connections to containers except filling
pipes, safety relief connections, and liquid-level gaging and pressure
gage connections provided with orifices not larger than No. 54 drill
size as required in paragraphs (b)(6) (iv) and (v) of this section shall
be equipped with excess-flow valves.
(iii) Each storage container shall be provided with a pressure gage
graduated from 0 to 400 p.s.i. Gages shall be designated for use in
ammonia service.
(iv) All containers shall be equipped with vapor return valves.
(3) Safety-relief devices. (i) Every container shall be provided
with one or more safety-relief valves of the spring-loaded or equivalent
type in accordance with paragraph (b)(9) of this section.
(ii) The rate of discharge of spring-loaded safety relief valves
installed on underground containers may be reduced to a minimum of 30
percent of the rate of discharge specified in Table H-36. Containers so
protected shall not be uncovered after installation until the liquid
ammonia has been removed. Containers which may contain liquid ammonia
before being installed underground and before being completely covered
with earth are to be considered aboveground containers when determining
the rate of discharge requirements of the safety-relief valves.
(iii) On underground installations where there is a probability of
the manhole or housing becoming flooded, the discharge from vent lines
shall be located above the high water level. All manholes or housings
shall be provided with ventilated louvers or their equivalent, the area
of such openings equalling or exceeding combined discharge areas of
safety-relief valves and vent lines which discharge their content into
the manhole housing.
(iv) Vent pipes, when used, shall not be restricted or of smaller
diameter than the relief-valve outlet connection.
(v) If desired, vent pipes from two or more safety-relief devices
located on the same unit, or similar lines from two or more different
units may be run into a common discharge header, provided the capacity
of such header is at least equal to the sum of the capacities of the
individual discharge lines.
(4) Reinstallation of containers. (i) Containers once installed
under ground shall not later be reinstalled above ground or under
ground, unless they successfully withstand hydrostatic pressure retests
at the pressure specified for the original hydrostatic test as required
by the code under which constructed and show no evidence of serious
corrosion.
(ii) Where containers are reinstalled above ground, safety devices
or gaging devices shall comply with paragraph (b)(9) of this section and
this paragraph respectively for aboveground containers.
(5) Installation of storage containers. (i) Containers installed
above ground, except as provided in paragraph (c)(5)(v) of this section
shall be provided with substantial concrete or masonry supports, or
structural steel supports on firm concrete or masonry foundations. All
foundations shall extend below the frost line.
(ii) Horizontal aboveground containers shall be so mounted on
foundations as to permit expansion and contraction. Every container
shall be supported to prevent the concentration of excessive loads on
the supporting portion of the shell. That portion of the container in
contact with foundations or saddles shall be protected against
corrosion.
(iii) Containers installed under ground shall be so placed that the
top of the container is below the frost line and in no case less than 2
feet below the surface of the ground. Should ground conditions make
compliance with these requirements impracticable, installation shall be
made otherwise to prevent physical damage. It will not be necessary to
cover the portion of the
[[Page 342]]
container to which manhole and other connections are affixed. When
necessary to prevent floating, containers shall be securely anchored or
weighted.
(iv) Underground containers shall be set on a firm foundation (firm
earth may be used) and surrounded with earth or sand well tamped in
place. The container, prior to being placed under ground, shall be given
a corrosion resisting protective coating. The container thus coated
shall be so lowered into place as to prevent abrasion or other damage to
the coating.
(v) Containers with foundations attached (portable or semiportable
tank containers with suitable steel ``runners'' or ``skids'' and
commonly known in the industry as ``skid tanks'') shall be designed and
constructed in accordance with paragraph (c)(1) of this section.
(vi) Secure anchorage or adequate pier height shall be provided
against container flotation wherever sufficiently high flood water might
occur.
(vii) The distance between underground containers of over 2,000
gallons capacity shall be at least 5 feet.
(6) Protection of appurtenances. (i) Valves, regulating, gaging, and
other appurtenances shall be protected against tampering and physical
damage. Such appurtenances shall also be protected during transit of
containers.
(ii) All connections to underground containers shall be located
within a dome, housing, or manhole and with access thereto by means of a
substantial cover.
(7) Damage from vehicles. Precaution shall be taken against damage
to ammonia systems from vehicles.
(d) Refrigerated storage systems. This paragraph applies to systems
utilizing containers with the storage of anhydrous ammonia under
refrigerated conditions. All applicable rules of paragraph (b) of this
section apply to this paragraph unless otherwise noted.
(1) Design of containers. (i) The design temperature shall be the
minimum temperature to which the container will be refrigerated.
(ii) Containers with a design pressure exceeding 15 p.s.i.g. shall
be constructed in accordance with paragraph (b)(2) of this section, and
the materials shall be selected from those listed in API Standard 620,
Recommended Rules for Design and Construction of Large, Welded, Low-
Pressure Storage Tanks, Fourth Edition, 1970, Tables 2.02, R2.2,
R2.2(A), R2.2.1, or R2.3 which are incorporated by reference as
specified in Sec. 1910.6.
(iii) Containers with a design pressure of 15 p.s.i.g. and less
shall be constructed in accordance with the applicable requirements of
API Standard 620 including its appendix R.
(iv) When austenitic steels or nonferrous materials are used, the
Code shall be used as a guide in the selection of materials for use at
the design temperature.
(v) The filling density for refrigerated storage containers shall be
such that the container will not be liquid full at a liquid temperature
corresponding to the vapor pressure at the start-to-discharge pressure
setting of the safety-relief valve.
(2) Installation of refrigerated storage containers. (i) Containers
shall be supported on suitable noncombustible foundations designed to
accommodate the type of container being used.
(ii) Adequate protection against flotation or other water damage
shall be provided wherever high flood water might occur.
(iii) Containers for product storage at less than 32 [deg]F. shall
be supported in such a way, or heat shall be supplied, to prevent the
effects of freezing and consequent frost heaving.
(3) Shutoff valves. When operating conditions make it advisable, a
check valve shall be installed on the fill connection and a remotely
operated shutoff valve on other connections located below the maximum
liquid level.
(4) Safety relief devices. (i) Safety relief valves shall be set to
start-to-discharge at a pressure not in excess of the design pressure of
the container and shall have a total relieving capacity sufficient to
prevent a maximum pressure in the container of more than 120 percent of
the design pressure. Relief valves for refrigerated storage containers
shall be self-contained spring-loaded, weight-loaded, or self-contained
pilot-operated type.
(ii) The total relieving capacity shall be the larger of:
[[Page 343]]
(a) Possible refrigeration system upset such as (1) cooling water
failure, (2) power failure, (3) instrument air or instrument failure,
(4) mechanical failure of any equipment, (5) excessive pumping rates.
(b) Fire exposure determined in accordance with Compressed Gas
Association (CGA) S-1, Part 3, Safety Relief Device Standards for
Compressed Gas Storage Containers, 1959, which is incorporated by
reference as specified in Sec. 1910.6, except that ``A'' shall be the
total exposed surface area in square feet up to 25 foot above grade or
to the equator of the storage container if it is a sphere, whichever is
greater. If the relieving capacity required for fire exposure is greater
than that required by (a) of this subdivision, the additional capacity
may be provided by weak roof to shell seams in containers operating at
essentially atmospheric pressure and having an inherently weak roof-to-
shell seam. The weak roof-to-shell seam is not to be considered as
providing any of the capacity required in (a) of this subdivision.
(iii) If vent lines are installed to conduct the vapors from the
relief valve, the back pressure under full relieving conditions shall
not exceed 50 percent of the start-to-discharge pressure for pressure
balanced valves or 10 percent of the start-to-discharge pressure for
conventional valves. The vent lines shall be installed to prevent
accumulation of liquid in the lines.
(iv) The valve or valve installation shall provide weather
protection.
(v) Atmospheric storage shall be provided with vacuum breakers.
Ammonia gas, nitrogen, methane, or other inert gases can be used to
provide a pad.
(5) Protection of container appurtenances. Appurtenances shall be
protected against tampering and physical damage.
(6) Reinstallation of refrigerated storage containers. Containers of
such size as to require field fabrication shall, when moved and
reinstalled, be reconstructed and reinspected in complete accordance
with the requirements under which they were constructed. The containers
shall be subjected to a pressure retest and if rerating is necessary,
rerating shall be in accordance with applicable requirements.
(7) Damage from vehicles. Precaution shall be taken against damage
from vehicles.
(8) Refrigeration load and equipment. (i) The total refrigeration
load shall be computed as the sum of the following:
(a) Load imposed by heat flow into the container caused by the
temperature differential between design ambient temperature and storage
temperature.
(b) Load imposed by heat flow into the container caused by maximum
sun radiation.
(c) Maximum load imposed by filling the container with ammonia
warmer than the design storage temperature.
(ii) More than one storage container may be handled by the same
refrigeration system.
(9) Compressors. (i) A minimum of two compressors shall be provided
either of which shall be of sufficient size to handle the loads listed
in paragraphs (d)(8)(i) (a) and (b) of this section. Where more than two
compressors are provided minimum standby equipment equal to the largest
normally operating equipment shall be installed. Filling compressors may
be used as standby equipment for holding compressors.
(ii) Compressors shall be sized to operate with a suction pressure
at least 10 percent below the minimum setting of the safety valve(s) on
the storage container and shall withstand a suction pressure at least
equal to 120 percent of the design pressure of the container.
(10) Compressor drives. (i) Each compressor shall have its
individual driving unit.
(ii) An emergency source of power of sufficient capacity to handle
the loads listed in paragraphs (d)(8)(i) (a) and (b) of this section
shall be provided unless facilities are available to safely dispose of
vented vapors while the refrigeration system is not operating.
(11) Automatic control equipment. (i) 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
container(s).
(ii) An emergency alarm system shall be installed to function in the
event the pressure in the container(s) rises to
[[Page 344]]
the maximum allowable operating pressure.
(iii) 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.
(iv) All automatic controls shall be installed in a manner to
preclude operation of alternate compressors unless the controls will
function with the alternate compressors.
(12) Separators for compressors. (i) An entrainment separator of
suitable size and design pressure shall be installed in the compressor
suction line of lubricated compression. The separator shall be equipped
with a drain and gaging device.
(ii) [Reserved]
(13) Condensers. The condenser system may be cooled by air or water
or both. The condenser shall be designed for at least 250 p.s.i.g.
Provision shall be made for purging noncondensibles either manually or
automatically.
(14) Receiver and liquid drain. A receiver shall be provided with a
liquid-level control to discharge the liquid ammonia to storage. The
receiver shall be designed for at least 250 p.s.i.g. and be equipped
with the necessary connections, safety valves, and gaging device.
(15) Insulation. Refrigerated containers and pipelines which 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 shall be of
a type which will not support flame propagation.
(e) Systems utilizing portable DOT containers--(1) Conformance.
Cylinders shall comply with DOT specifications and shall be maintained,
filled, packaged, marked, labeled, and shipped to comply with 49 CFR
chapter I and Marking Portable Compressed Gas Containers to Identify the
Material Contained, ANSI Z48.1-1954 (R1970), which is incorporated by
reference as specified in Sec. 1910.6.
(2) Storage. Cylinders shall be stored in an area free from
ignitable debris and in such manner as to prevent external corrosion.
Storage may be indoors or outdoors.
(3) Heat protection. Cylinders filled in accordance with DOT
regulations will become liquid full at 145 [deg]F. Cylinders shall be
protected from heat sources such as radiant flame and steampipes. Heat
shall not be applied directly to cylinders to raise the pressure.
(4) Protection. Cylinders shall be stored in such manner as to
protect them from moving vehicles or external damage.
(5) Valve cap. Any cylinder which is designed to have a valve
protection cap shall have the cap securely in place when the cylinder is
not in service.
(f) Tank motor vehicles for the transportation of ammonia. (1) This
paragraph applies to containers and pertinent equipment mounted on tank
motor vehicles including semitrailers and full trailers used for the
transportation of ammonia. This paragraph does not apply to farm
vehicles. For requirements covering farm vehicles, refer to paragraphs
(g) and (h) of this section.
Paragraph (b) of this section applies to this paragraph unless otherwise
noted. Containers and pertinent equipment for tank motor vehicles for
the transportation of anhydrous ammonia, in addition to complying with
the requirements of this section, shall also comply with the
requirements of DOT.
(2) Design pressure and construction of containers. (i) The minimum
design pressure for containers shall be that specified in the
regulations of the DOT.
(ii) The shell or head thickness of any container shall not be less
than three-sixteenth inch.
(iii) All container openings, except safety relief valves, liquid-
level gaging devices, and pressure gages, shall be labeled to designate
whether they communicate with liquid or vapor space.
(3) Container appurtenances. (i) All appurtenances shall be
protected against physical damage.
(ii) All connections to containers, except filling connections,
safety relief devices, and liquid-level and pressure gage connections,
shall be provided with suitable automatic excess flow valves, or in lieu
thereof, may be fitted with quick-closing internal valves, which shall
remain closed except during delivery operations. The control mechanism
for such valves may be provided with a secondary control remote
[[Page 345]]
from the delivery connections and such control mechanism shall be
provided with a fusible section (melting point 208 [deg]F. to 220
[deg]F.) which will permit the internal valve to close automatically in
case of fire.
(iii) Filling connections shall be provided with automatic back-
pressure check valves, excess-flow valves, or quick-closing internal
valves, to prevent back-flow in case the filling connection is broken.
Where the filling and discharge connect to a common opening in the
container shell and that opening is fitted with a quick-closing internal
valve as specified in paragraph (f)(3)(ii) of this section, the
automatic valve shall not be required.
(iv) All containers shall be equipped for spray loading (filling in
the vapor space) or with an approved vapor return valve of adequate
capacity.
(4) Piping and fittings. (i) All piping, tubing, and fittings shall
be securely mounted and protected against damage. Means shall be
provided to protect hoses while the vehicle is in motion.
(ii) Fittings shall comply with paragraph (b)(6) of this section.
Pipe shall be Schedule 80.
(5) Safety relief devices. (i) The discharge from safety relief
valves shall be vented away from the container upward and unobstructed
to the open air in such a manner as to prevent any impingement of
escaping gas upon the container; loose-fitting rain caps shall be used.
Size of discharge lines from safety valves shall not be smaller than the
nominal size of the safety-relief valve outlet connection. Suitable
provision shall be made for draining condensate which may accumulate in
the discharge pipe.
(ii) Any portion of liquid ammonia piping which at any time may be
closed at both ends shall be provided with a hydrostatic relief valve.
(6) Transfer of liquids. (i) The content of tank motor vehicle
containers shall be determined by weight, by a suitable liquid-level
gaging device, or other approved methods. If the content of a container
is to be determined by liquid-level measurement, the container shall
have a thermometer well so that the internal liquid temperature can be
easily determined. This volume when converted to weight shall not exceed
the filling density specified by the DOT.
(ii) Any pump, except a constant speed centrifugal pump, shall be
equipped with a suitable pressure actuated bypass valve permitting flow
from discharge to suction when the discharge pressure rises above a
predetermined point. Pump discharge shall also be equipped with a
spring-loaded safety relief valve set at a pressure not more than 135
percent of the setting of the bypass valve or more than 400 p.s.i.g.,
whichever is larger.
(iii) Compressors shall be equipped with manually operated shutoff
valves on both suction and discharge connections. Pressure gages of
bourdon-tube type shall be installed on the suction and discharge of the
compressor before the shutoff valves. The compressor shall not be
operated if either pressure gage is removed or is inoperative. A spring-
loaded, safety-relief valve capable of discharging to atmosphere the
full flow of gas from the compressor at a pressure not exceeding 300
p.s.i.g. shall be connected between the compressor discharge and the
discharge shutoff valve.
(iv) Valve functions shall be clearly and legibly identified by
metal tags or nameplates permanently affixed to each valve.
(7)-(8) [Reserved]
(9) Chock blocks. At least two chock blocks shall be provided. These
blocks shall be placed to prevent rolling of the vehicle whenever it is
parked during loading and unloading operations.
(10) Portable tank containers (skid tanks). Where portable tank
containers are used for farm storage they shall comply with paragraph
(c)(1) of this section. When portable tank containers are used in lieu
of cargo tanks and are permanently mounted on tank motor vehicles for
the transportation of ammonia, they shall comply with the requirements
of this paragraph.
(g) Systems mounted on farm vehicles other than for the application
of ammonia--(1) Application. This paragraph applies to containers of
1,200 gallons capacity or less and pertinent equipment mounted on farm
vehicles (implements of husbandry) and used other than for the
application of ammonia to the soil.
[[Page 346]]
Paragraph (b) of this section applies to this paragraph unless otherwise
noted.
(2) Design pressure and classification of containers. (i) The
minimum design pressure for containers shall be 250 p.s.i.g.
(ii) The shell or head thickness of any container shall be not less
than three-sixteenths of an inch.
(3) Mounting containers. (i) A suitable ``stop'' or ``stops'' shall
be mounted on the vehicle or on the container in such a way that the
container shall not be dislodged from its mounting due to the vehicle
coming to a sudden stop. Back slippage shall also be prevented by proper
methods.
(ii) A suitable ``hold down'' device shall be provided which will
anchor the container to the vehicle at one or more places on each side
of the container.
(iii) When containers are mounted on four-wheel trailers, care shall
be taken to insure that the weight is distributed evenly over both
axles.
(iv) When the cradle and the tank are not welded together suitable
material shall be used between them to eliminate metal-to-metal
friction.
(4) Container appurtenances. (i) All containers shall be equipped
with a fixed liquid-level gage.
(ii) All containers with a capacity exceeding 250 gallons shall be
equipped with a pressure gage having a dial graduated from 0-400 p.s.i.
(iii) The filling connection shall be fitted with combination back-
pressure check valve and excess-flow valve; one double or two single
back-pressure check valves; or a positive shutoff valve in conjunction
with either an internal back-pressure check valve or an internal excess
flow valve.
(iv) All containers with a capacity exceeding 250 gallons shall be
equipped for spray loading or with an approved vapor return valve.
(v) All vapor and liquid connections except safety-relief valves and
those specifically exempted by paragraph (b)(6)(v) of this section shall
be equipped with approved excess-flow valves or may be fitted with
quick-closing internal valves which, except during operating periods,
shall remain closed.
(vi) Fittings shall be adequately protected from damage by a metal
box or cylinder with open top securely fastened to the container or by
rigid guards, well braced, welded to the container on both sides of the
fittings or by a metal dome. If a metal dome is used, the relief valve
shall be properly vented through the dome.
(vii) If a liquid withdrawal line is installed in the bottom of a
container, the connections thereto, including hose, shall not be lower
than the lowest horizontal edge of the vehicle axle.
(viii) Provision shall be made to secure both ends of the hose while
in transit.
(5) Marking the container. There shall appear on each side and on
the rear end of the container in letters at least 4 inches high, the
words, ``Caution--Ammonia'' or the container shall be marked in
accordance with DOT regulations.
(6) Farm vehicles. (i) Farm vehicles shall conform with State
regulations.
(ii) All trailers shall be securely attached to the vehicle drawing
them by means of drawbars supplemented by suitable safety chains.
(iii) A trailer shall be constructed so that it will follow
substantially in the path of the towing vehicle and will not whip or
swerve dangerously from side to side.
(iv) All vehicles shall carry a can containing 5 gallons or more of
water.
(h) Systems mounted on farm vehicles for the application of ammonia.
(1) This paragraph applies to systems utilizing containers of 250
gallons capacity or less which are mounted on farm vehicles (implement
of husbandry) and used for the application of ammonia to the soil.
Paragraph (b) of this section applies to this paragraph unless otherwise
noted. Where larger containers are used, they shall comply with
paragraph (g) of this section.
(2) Design pressure and classification of containers. (i) The
minimum design pressure for containers shall be 250 p.s.i.g.
(ii) The shell or head thickness of any container shall not be less
than three-sixteenths inch.
(3) Mounting of containers. All containers and flow-control devices
shall be securely mounted.
[[Page 347]]
(4) Container valves and accessories. (i) Each container shall have
a fixed liquid-level gage.
(ii) The filling connection shall be fitted with a combination back-
pressure check valve and an excess-flow valve; one double or two single
back-pressure check valves: or a positive shutoff valve in conjunction
with an internal back-pressure check valve or an internal excess-flow
valve.
(iii) The applicator tank may be filled by venting to open air
provided the bleeder valve orifice does not exceed seven-sixteenths inch
in diameter.
(iv) Regulation equipment may be connected directly to the tank
coupling or flange, in which case a flexible connection shall be used
between such regulating equipment and the remainder of the liquid
withdrawal system. Regulating equipment not so installed shall be
flexibly connected to the container shutoff valve.
(v) No excess flow valve is required in the liquid withdrawal line
provided the controlling orifice between the contents of the container
and the outlet of the shutoff valve does not exceed seven-sixteenths
inch in diameter.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49748, Oct. 24, 1978;
49 FR 5322, Feb. 10, 1984; 53 FR 12122, Apr. 12, 1988; 61 FR 9238, Mar.
7, 1996; 63 FR 1269, Jan. 8, 1998; 63 FR 33466, June 18, 1998]
