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 511 - Safety Relief Valves

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a)
					 Every vessel used in anhydrous ammonia service shall be fitted with 1 or more
					 safety relief valves in direct communication with the vapor space. These safety
					 relief valves shall be of the spring-loaded type suitable for anhydrous ammonia
					 service. The discharge from safety relief valves shall be full size and be
					 directed away from the vessel, and shall discharge upward and unobstructed to
					 the open air.
All relief-valve discharge openings shall have suitable
						loose-fitting 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 in the discharge pipe.
The safety relief valves for anhydrous ammonia service
						shall be set to start to discharge with relation to the allowable working
						pressure of the vessel as follows:
Pressure vessels constructed in accordance
								with:
Minimum
Maximum
Code paragraphs U-68 and
								U-69..........................
110%
125%
Code paragraphs U-200, through 1974
								edition..........................
100%
110%
API-ASME
								Code..........................
100%
110%
DOT Cylinders
As required by
								DOT Regulations
(b) Except for code paragraphs U-68 and U-69
					 tanks, the discharge capacity of safety relief valves for anhydrous ammonia
					 tanks shall be sufficient to prevent pressure in the tank from exceeding 120
					 percent of the allowable working pressure of the tank. ASME code paragraphs
					 U-68 and U-69 tanks shall have safety valve capacity sufficient to prevent
					 pressure in the tank from exceeding 135 percent of the allowable working
					 pressure of the tank. All safety relief valves required by this Order shall be
					 ASME rated and stamped. The minimum required rate of discharge of safety relief
					 valves for anhydrous ammonia tanks shall be in accordance with the following
					 table:
Surface area sq.
								ft.
Flow rate CFM
								air
Surface area sq.
								ft.
Flow rate CFM
								air
Surface area sq.
								ft.
Flow rate CFM
								air
20 or less..........................
258
..........................185
1,600
..........................
								900
5,850
25..........................
310
..........................190
1,640
..........................
								950
6,120
30..........................
360
..........................195
1,670
..........................1,000
6,380
35..........................
408
..........................200
1,710
..........................1,050
6,640
40..........................
455
..........................210
1,780
..........................1,100
6,900
45..........................
501
..........................220
1,850
..........................1,150
7,160
50..........................
547
..........................230
1,920
..........................1,200
7,410
55..........................
591
..........................240
1,980
..........................1,250
7,660
60..........................
635
..........................250
2,050
..........................1,300
7,910
65..........................
678
..........................260
2,120
..........................1,350
8,160
70..........................
720
..........................270
2,180
..........................1,400
8,410
75..........................
762
..........................280
2,250
..........................1,450
8,650
80..........................
804
..........................290
2,320
..........................1,500
8,900
85..........................
845
..........................300
2,380
..........................1,550
9,140
90..........................
885
..........................310
2,450
..........................1,600
9,380
95..........................
925
..........................320
2,510
..........................1,650
9,620
100..........................
965
..........................330
2,570
..........................1,700
9,860
105..........................
1,010
..........................340
2,640
..........................1,750
10,090
110..........................
1,050
..........................350
2,700
..........................1,800
10,330
115..........................
1,090
..........................360
2,760
..........................1,850
10,560
120..........................
1,120
..........................370
2,830
..........................1,900
10,800
125..........................
1,160
..........................380
2,890
..........................1,950
11,030
130..........................
1,200
..........................390
2,950
..........................2,000
11,260
135..........................
1,240
..........................400
3,010
..........................2,050
11,490
140..........................
1,280
..........................450
3,320
..........................2,100
11,720
145..........................
1,310
..........................500
3,620
..........................2,150
11,950
150..........................
1,350
..........................550
3,910
..........................2,200
12,180
155..........................
1,390
..........................600
4,200
..........................2,250
12,400
160..........................
1,420
..........................650
4,480
..........................2,300
12,630
165..........................
1,460
..........................700
4,760
..........................2,350
12,850
170..........................
1,500
..........................750
5,040
..........................2,400
13,080
175..........................
1,530
..........................800
5,300
..........................2,450
13,300
180..........................
1,570
..........................850
5,590
..........................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 containers 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 degrees Fahrenheit and atmospheric pressure
						(14.7 psia).
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 = 22.11A0.82,
						where A = outside surface area of the container in square feet.
The minimum required rate of discharge of safety relief
						valves for anhydrous ammonia DOT cylinders shall be in accordance with the
						regulations of the Bureau of Explosives.