California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 7 - General Industry Safety Orders › Group 20 - Flammable Liquids, Gases and Vapors › Article 145 - Tank Storage › Section 5598 - Vents for Underground Tanks

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) Location and arrangement of vents for
						Category 1 or 2 flammable liquids, or Category 3 flammable liquids with a
						flashpoint below 100 °F (37.8 °C). Vent pipes from underground storage
						tanks storing Category 1 or 2 flammable liquids, or Category 3 flammable
						liquids with a flashpoint below 100 °F (37.8 °C) shall be so located
						that the discharge point is outside of buildings, higher than the fill pipe
						opening, and not less than 12 feet above the adjacent ground level. Vent pipes
						shall not be obstructed by devices that will cause excessive back pressure.
						Vent outlets shall be so located and directed that flammable vapors will not
						accumulate or travel to an unsafe location, enter building openings or be
						trapped under eaves or other obstructions. Tanks containing Category 1
						flammable liquids shall be equipped with pressure and vacuum venting devices
						which shall be normally closed except when venting to pressure or vacuum
						conditions. Tanks storing Category 2 or 3 flammable liquids with a flashpoint
						below 73 °F (22.8 °C) shall be equipped with pressure-vacuum vents or
						with approved flame arresters.
(b)
						Each tank shall be vented through piping adequate in size to prevent blow-back
						of vapor or liquid at the fill opening while tank is being filled. Vent pipes
						shall be not less than 1 ¼ -inch nominal inside diameter. The vent size
						depends upon the filling or withdrawal rate whichever is larger, the vent line
						length and the tank design pressure. Vent piping sized in accordance with Table
						FL-18 will prevent the pressure in the tank from exceeding 2.5 psig.
Table FL-18
Vent Line Diameters
Maximum Flow
								  GPM
50 Feet
Pipe Length 
								  * 100
								  Feet
200 Feet
100
1 ¼ -inch
1 ¼
								  -inch
1 ¼ -inch
200
1 ¼ -inch
1 ¼
								  -inch
1 ¼ -inch
300
1 ¼ -inch
1 ¼
								  -inch
1 ½ -inch
400
1 ¼ -inch
1 ½
								  -inch
2-inch
500
1 ½ -inch
1 ½
								  -inch
2-inch
600
1 ½
								  -inch
2-inch
2-inch
700
2-inch
2-inch
2-inch
800
2-inch
2-inch
3-inch
900
2-inch
2-inch
3-inch
1,000
2-inch
2-inch
3-inch
* Vent lines of 50 feet, 100 feet, and 200 feet of pipe
						  plus 7 ells.
(c) Location
						and arrangement of vents for Category 3 flammable liquids with a flashpoint at
						or above 100 °F (37.8 °C), Category 4 flammable liquids and liquids
						with a flashpoint greater than 199.4 °F (93 °C) (formerly designated
						Class IIIB Combustible liquids). Vent pipes from tanks storing Category 3
						flammable liquids with a flashpoint at or above 100 °F (37.8 °C),
						Category 4 flammable liquids or liquids with a flashpoint greater than 199.4
						°F (93 °C) (formerly designated Class IIIB Combustible liquids) shall
						terminate outside of building and higher than the fill pipe opening. Vent
						outlets shall be above normal snow level. They may be fitted with return bends,
						course screens or other devices to minimize ingress of foreign
						material.
(d) Vent piping shall be
						constructed in accordance with Article 146. Vent pipes shall be so laid as to
						drain toward the tank without sags or traps in which liquid can collect. They
						shall be located so that they will not be subjected to physical damage. The
						tank end of the vent pipe shall enter the tank through the top.
(e) When tank vent piping is manifolded, pipe
						sizes shall be such as to discharge, within the pressure limitations of the
						system, the vapors they may be required to handle when manifolded tanks are
						filled simultaneously.
(f) Vent
						piping for tanks storing Category 1 or 2 flammable liquids, or Category 3
						flammable liquids with a flashpoint below 100 °F (37.8 °C) liquids
						shall not be manifolded with vent piping for tanks storing Category 3 flammable
						liquids with a flashpoint at or above 100 °F (37.8 °C) or Category 4
						flammable liquids or liquids with a flashpoint greater than 199.4 °F (93
						°C) (formerly designated Class IIIB Combustible liquids) unless positive
						means are provided to prevent the vapors from Category 1 or 2 flammable
						liquids, or Category 3 flammable liquids with a flashpoint below 100 °F
						(37.8 °C) from entering tanks storing Category 3 flammable liquids with a
						flashpoint at or above 100 °F (37.8 °C) or Category 4 flammable liquids
						or liquids with a flashpoint greater than 199.4 °F (93 °C) (formerly
						designated Class IIIB Combustible liquids), to prevent contamination and
						possible change in classification of the less volatile liquid.
1.
						  Amendment of subsections (a), (c) and (f) and new NOTE filed 5-5-2014;
						  operative 5-6-2014 pursuant to Government Code section
						  11343.4(b)(3)
						  (Register 2014, No. 19).
Note: Authority cited: Section
							 142.3, Labor
							 Code. Reference: Section
							 142.3, Labor
							 Code.