California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 1 - Unfired Pressure Vessel Safety Orders › Article 6 - Anhydrous Ammonia › Section 501 - Installation of Aboveground Storage Tanks for Other than Refrigeration Service

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) Stationary
					 tanks shall be installed aboveground on firm masonry or concrete foundations,
					 or on full length skids providing a bearing area limiting foundation loadings
					 to not more than 2,000 pounds per square foot. Unless supported by continuous
					 skids welded to pads on the tank shell, aboveground horizontal storage tanks
					 shall have no more than 2 points of support longitudinally. Where necessary,
					 tanks shall be securely anchored or weighted to prevent floating.
A tank may be installed on saddles, directly on concrete
						foundations, or it may be supported by properly designed metallic structural
						supports. When the tank is installed directly on concrete foundations, a
						corrosion pad shall be provided at the points of contact with the foundation.
						These corrosion pads shall be at least 
						3/16 inch
						thick, and shall have a width at least equal to the width of the foundation at
						the point of contact with the tank, but in no case shall they be less than 8
						times the shell thickness in width.
When corrosion pads or pad-type steel supports are used,
						the pad shall have rounded or semielliptically shaped ends, and shall be
						attached to the shell with a continuous seal weld. Corrosion pads shall be not
						less than ¼ the circumference of the shell in length.
Unless installed on concrete pads, skid tanks shall be
						placed on engineered soil or road base topped with well-drained gravel or oiled
						sand, capable of supporting 2,000 pounds per square foot.
Sufficient space shall be provided between stationary
						storage tanks to permit access for fire fighting. This space shall not be less
						than 5 feet for tanks over 1,200-gallon capacity. Tanks exceeding 1,200-gallon
						capacity shall be so installed that the bottom outside surface of the tank is
						at least 12 inches above ground level.
(b) All tanks over 1,200-gallon capacity
					 shall be installed on foundations in such a manner as to permit expansion and
					 contraction. Every tank shall be so supported as to prevent the concentration
					 of excessive loads on the tank at the points of support. All foundations and
					 fastenings shall be designed to provide reasonable safety under imposed
					 loadings, including wind, earthquake, vibrations, etc.
(c) Containers shall be located outside of
					 buildings, or in buildings or sections thereof especially equipped for this
					 service. Consideration shall be given to the adverse health effects of ammonia,
					 as well as the adjacent fire hazards, when selecting the location for a storage
					 container.
Storage areas shall be kept free of readily ignitible
						materials such as waste, weeds, and long dry grass.
Stationary storage tanks shall be located with relation
						to property lines, residential buildings, highways, etc., in accordance with
						the following table:
Minimum
								  distance (feet) from tank to
Capacity of tank in U.S.
								gallons
Line of property adjoining which may be built
								upon
Highway or main track of
								railroad
Residential building
1,200 and less
50
25
50
Over 1,200 to and including 30,000
50
50
50
Over 30,000 to and including 70,000
65
50
65
Over 70,000 to and including
								500,000
100
50
100
Over
								500,000
150
50
150
Minimum
								  distance (feet) from tank to
Capacity of tank in U.S.
								gallons
Any Building or area used by the public for
								deliberation, worship, education, entertainment, amusement, or awaiting
								transportation
Hospital, jail or other similar
								institutions
Open well, reservoir, or other source of
								potable water
1,200 and
								less
250
750
50
Over 1,200 to and including
								30,000
400
1,000
100
Over 30,000 to and including
								70,000
520
1,300
100
Over 70,000 to and including
								500,000
800
2,000
200
Over
								500,000
1,000
2,500
200
Electrical equipment and wiring for use in ammonia
						installations shall be general purpose or weather resistant as
						appropriate.
Electrical systems shall be installed and maintained in
						accordance with the Electrical Safety Orders.
(d) Where vehicle impact is possible or
					 likely stationary tanks shall be protected against vehicle damage by a rugged
					 fence, suitable crash posts, curbs, or other acceptable protection. All storage
					 tanks located where unauthorized tampering is possible shall be surrounded with
					 a rugged steel fence or equivalent, or all liquid and vapor outlets shall be
					 kept effectively locked when not in use.
(e) All stationary storage tanks exceeding
					 1,200 gallons capacity shall have the loading and unloading connections secured
					 to a concrete bulkhead or equivalent designed to withstand a horizontal pull of
					 not less than 2,000 pounds in any direction, unless other suitable protection
					 is provided. This bulkhead shall not be located underneath the tank. The
					 loading and unloading connections shall be firmly secured to this bulkhead and
					 the piping between the bulkhead and tank shall be installed in a manner to
					 provide for expansion, contraction, jarring, vibrations, settling, etc. For
					 skid tanks exceeding 1,200 gallons capacity, such loading and unloading
					 connections shall be securely fastened to the skid or to the tank supports.
NOTE: 2,000 pounds may not be adequate for all sizes of
						loading and unloading hoses and connections.
(f) Where excess-flow valves [See Section
					 507 (e)] are used,
					 liquid and vapor lines shall be at least full size from the excess-flow valve
					 in the tank to the point of discharge or an additional excess-flow valve or
					 equivalent shall be located as close to the point of pipe size reduction or
					 other restriction as is practical, unless the excess-flow valve in the tank is
					 designed to operate at the reduced flow condition, in which case the
					 excess-flow valve in the tank may suffice.
Where excess-flow valves are used and 2 or more tanks are
						installed in battery, with common loading and/or unloading lines, the common
						liquid and vapor lines shall be fitted with excess-flow valves or equivalent
						(unless the common line has a cross-sectional area equal to or in excess of the
						combined areas of the individual tank lines; or unless the excess-flow valves
						are designed to operate at the reduced flow condition, in which case the
						excess-flow valve in the tank may suffice). Where additional excess-flow valves
						are used in common loading and/or unloading lines, the additional excess-flow
						valve or equivalent shall be located as close to the point of restriction as
						practical.
NOTE: A quick-closing manually operated valve may be
						considered equivalent to an excess-flow valve at the point of pipe size
						reduction or other restriction providing:
(1) It is equipped with a means of closing
					 the valve manually from a point remote from the delivery connection.
(2) The loading and/or unloading line in
					 which it is located is secured to a bulkhead complying with Section
					 501 (e).
(3) The quick-closing valve is in the
					 pipeline on the tank side of the bulkhead.