CMC · California Mechanical Code
What identification and spill containment (receptor) requirements apply to liquid HPP?
If a process pipe qualifies as Hazardous Process Piping (HPP) and carries liquids, California Mechanical Code requires the pipe to be visibly identified and—if routed above other occupancies or exit corridors—to have a physical receptor installed beneath it that collects any leakage and drains to an approved place; you cannot use the 1‑hour enclosure as that receptor (see §§ 1406.2 and 1406.2.1.3).
Last reviewed: July 6, 2026
What the code requires — 2–4 sentences
The California Mechanical Code requires that Hazardous Process Piping (HPP) be visibly identified and, when carrying liquid HPP, have an approved means to direct spilled material to containment or drainage. For HPP piping routed in spaces above or adjacent to other occupancies (including over exit corridors), a receptor (a collection device) must be installed beneath liquid HPP piping to collect any discharge or leakage and drain it to an approved location; the enclosure’s 1‑hour fire-rated assembly cannot serve as the receptor. See § 1406.2 and § 1406.2.1.3 of the CMC.
The bottom line: if a process pipe is HPP and it carries liquids, it must be labeled and have a physical receptor below it that collects leaks and drains to an approved place — and you cannot count the 1‑hour enclosure as the receptor. § 1406.2 and § 1406.2.1.3.
Requirements in detail
Key, short statements (code-grounded)
- Identification: HPP piping shall be identified in accordance with nationally recognized standards to indicate the material being transported (see § 1406.2).
- Visibility: HPP supply piping or tubing in service corridors shall be exposed to view (see § 1406.2).
- Spill routing: Liquid HPP piping shall have an approved means for directing spilled materials to an approved containment or drainage system (see § 1406.2).
- Receptor (when piping/tubing transports HPP liquids in the space above or within exit/other occupancies): A receptor shall be installed below such piping or tubing and shall be designed to collect discharge or leakage and drain it to an approved location; the 1‑hour enclosure shall not be used as part of the receptor (see § 1406.2.1.3).
- Drainage installation: Liquid HPP waste or drainage systems shall be installed in accordance with the plumbing code (see § 1406.2).
Decision-relevant dimensions and values (quick reference)
| Decision / question | Requirement or value | Where it’s stated (Code Reference) |
|---|---|---|
| Must HPP piping be labeled? | Yes — identified per nationally recognized standards | § 1406.2 |
| Must HPP in service corridors be exposed? | Yes — exposed to view | § 1406.2 cite |
| Is a receptor required for liquid HPP above other occupancies or exit corridors? | Yes — receptor installed below piping to collect and drain leakage | § 1406.2.1.3 |
| Can a 1‑hour enclosure be used as the receptor? | No — the 1‑hour enclosure shall not be used as part of the receptor | § 1406.2.1.3 |
| Where must collected spill drainage go? | To an approved location; drainage systems per the plumbing code | § 1406.2 |
(Note: the CMC text requires the receptor and drainage to an “approved location” but does not prescribe receptor sizing, minimum sump volumes, or the specific “nationally recognized standards” for labeling — see explanation below.)
What “approved” and “identified” mean here
- The CMC language uses terms approved and nationally recognized standards but does not list the specific standard or approval method in § 1406.2 or § 1406.2.1.3; compliance is by meeting the standard accepted by the Authority Having Jurisdiction (AHJ) or by reference standards adopted elsewhere. The CMC therefore sets the performance/installation obligation but expects the AHJ or referenced standards to supply technical specifics.
Exceptions & special cases
- Occasional transverse crossings of corridors by supply piping that are enclosed within the corridor space are exempt from the 1406.2.1.1–1406.2.1.6 corridor‑installation requirements (this can affect when receptors/space conditions apply). The CMC includes this exception in the same installation subsection; consult the AHJ about applicability.
- The CMC does not itself provide receptor sizing, containment volume requirements, or specific labeling formats; those technical details are to be obtained from referenced codes/standards or the AHJ (e.g., the plumbing code for drain sizing; other adopted standards for labeling). If you need numerical containment capacities or drain sizing, refer to the plumbing code and applicable fire/hazardous‑materials provisions.
Common mistakes
- Assuming the 1‑hour fire‑rated enclosure that contains HPP piping can serve as the receptor — the code explicitly forbids that (see § 1406.2.1.3).
- Not installing a receptor when HPP liquids are routed over other occupancies or exit corridors — § 1406.2.1.3 mandates a receptor whenever the piping/tubing transports HPP liquids in those spaces.
- Failing to route receptor drainage to an approved location, or assuming the receptor can simply pond without controlled drainage — the code requires drainage to an approved location and plumbing‑code compliance for the drainage system (see § 1406.2).
- Neglecting visible identification and reliance on concealed/painted‑only markers — the CMC requires HPP supply piping in service corridors to be exposed to view and identified per nationally recognized standards (see § 1406.2).
Worked example — concrete scenario (numbers are illustrative; CMC does not give sizing)
Scenario: A semiconductor fab has a 2‑inch stainless steel HPP supply line carrying a liquid process chemical routed in a service corridor above a room. The owner must provide identification and a receptor.
What the CMC requires (apply step‑by‑step)
- Identification: Label the line to indicate the material transported, per “nationally recognized standards” as required by § 1406.2. The CMC does not name the exact label standard; confirm the required marking convention with the AHJ (for example, many jurisdictions use ASME A13.1 for pipe marking, but the CMC itself only requires a nationally recognized standard).
- Visibility: Ensure the run in the service corridor is exposed to view (no concealed runs) as required by § 1406.2.
- Receptor: Install a receptor directly beneath the 2‑inch line where piping passes over the room/egress space. The receptor must be designed to collect leakage and drain it to an approved location (for example, a sloped trough feeding a dedicated drain). § 1406.2.1.3 requires the receptor and that the 1‑hour enclosure not be used as the receptor. The CMC does not prescribe receptor volume or drain size.
- Drain connection: Route receptor drainage to an approved location and ensure the drainage system installation complies with the plumbing code, per § 1406.2. That means have the plumbing designer size the drain for expected flow (leak plus any fire‑protection water if applicable) and obtain AHJ approval of the discharge point.
Example calculation note (illustrative, not code-mandated): If you design the receptor to capture a reasonable worst‑case rupture drip rate of 1 gpm and want 30 minutes of hold‑and‑pump capability, you’d size the collection or sump capacity at ~30 gallons plus margin. The CMC requires the receptor but not this numeric capacity — confirm actual sizing with the plumbing code and AHJ.
Related provisions (CMC sections)
- § 1406.1 — General requirements for process piping (materials, ratings, ASME B31.3).
- § 1406.2 — Hazardous Process Piping (identification; spill routing to approved containment/drainage; visibility in service corridors).
- § 1406.2.1.1 — Automatic sprinklers requirement in the space (installation context for piping spaces).
- § 1406.2.1.2 — Ventilation requirements for the space where piping is installed.
- § 1406.2.1.3 — Receptor requirement: collect discharge or leakage and drain to approved location; 1‑hour enclosure not part of receptor.
- § 1406.2.1.4 – .1.6 — Separation, emergency shutoffs, electrical wiring and other installation controls for HPP in corridor/above‑space conditions.
(For spill‑volume design, monitoring, alarm, and detailed drainage capacity rules, the plumbing code and the California Fire Code contain additional technical provisions; those codes should be consulted for numeric containment/drain sizing and monitoring requirements.)
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 1406.0 High relevance — show source text
1406.0 Pipe, Tubing, and Fittings.
1406.1 General. Process pipe, tubing, and fittings shall comply with ASME B31.3 and shall be installed in accordance with the manufacturer’s installation instructions. Materials shall be rated for the operating temperatures and pressures of the system, and shall be compatible with the type of liquid.
1406.2 Hazardous Process Piping (HPP). HPP supply piping or tubing in service corridors shall be exposed to view. HPP piping shall be identified in accordance with nationally recognized standards to indicate the material being transported. Liquid HPP piping shall have an approved means for directing spilled materials to an approved containment or drainage system.
Liquid HPP waste or drainage systems shall be installed in accordance with the plumbing code.
1406.2.1 Installation in Exit Corridors and Above Other Occupancies. Hazardous process supply pipe shall not be located within exit corridors, within a portion of a means of egress required to be enclosed in fire-resistive construction, or in concealed spaces in or above
2025 CALIFORNIA MECHANICAL CODE 335
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
PROCESS PIPING
areas not classified as Group H Occupancies, except as permitted by this subsection.
Hazardous production material piping and tubing shall be permitted to be installed within the space defined by the walls of exit corridors and the floor or roof above, or in concealed spaces above other occupancies in accordance with Section 1406.2.1.1 through Section 1406.2.1.6.
1406.2.1.1 Automatic Sprinklers. Automatic sprinklers shall be installed within the space unless the space is less than 6 inches (152 mm) in the least dimension.
1406.2.1.2 Ventilation. Ventilation at not less than
6 air changes per hour (ACH) shall be provided. The space shall not be used to convey air from other
areas.
1406.2.1.3 Receptor. Where the piping or tubing is used to transport HPP liquids, a receptor shall be installed below such piping or tubing. The receptor shall be designed to collect discharge or leakage and drain it to an approved location. The 1 hour enclosure shall not be used as part of the receptor.
1406.2.1.4 Separation. HPP supply piping and tubing and HPP nonmetallic waste lines shall be separated from the exit corridor and from an occupancy other than a semi-conductor fabrication facility classified as a Group H Occupancy by construction, as required for walls or partitions that have a fire-protection rating of not less than 1 hour. Where gypsum wallboard is used, joints on the piping side of the enclosure need not be taped, provided the joints occur over framing members. Access openings into the enclosure shall be protected by approved fire assemblies.
1406.2.1.5 Emergency Shutoff Valves. Readily accessible manual or automatic remotely activated fail-safe emergency shutoff valves shall be installed on piping and tubing other than waste lines at the following locations:
(1) At branch connections into the fabrication area.
(2) At entries into exit corridors. Excess flow valves shall be installed as required by the fire code.
CMC § 1406.2.1.1 High relevance — show source text
1406.2.1.1 Automatic Sprinklers. Automatic sprinklers shall be installed within the space unless the space is less than 6 inches (152 mm) in the least dimension.
1406.2.1.2 Ventilation. Ventilation at not less than
6 air changes per hour (ACH) shall be provided. The space shall not be used to convey air from other
areas.
1406.2.1.3 Receptor. Where the piping or tubing is used to transport HPP liquids, a receptor shall be installed below such piping or tubing. The receptor shall be designed to collect discharge or leakage and drain it to an approved location. The 1 hour enclosure shall not be used as part of the receptor.
1406.2.1.4 Separation. HPP supply piping and tubing and HPP nonmetallic waste lines shall be separated from the exit corridor and from an occupancy other than a semi-conductor fabrication facility classified as a Group H Occupancy by construction, as required for walls or partitions that have a fire-protection rating of not less than 1 hour. Where gypsum wallboard is used, joints on the piping side of the enclosure need not be taped, provided the joints occur over framing members. Access openings into the enclosure shall be protected by approved fire assemblies.
1406.2.1.5 Emergency Shutoff Valves. Readily accessible manual or automatic remotely activated fail-safe emergency shutoff valves shall be installed on piping and tubing other than waste lines at the following locations:
(1) At branch connections into the fabrication area.
(2) At entries into exit corridors. Excess flow valves shall be installed as required by the fire code.
1406.2.1.6 Electrical Wiring. Electrical wiring and equipment located in the piping space shall be approved for Class I, Division 2, Hazardous Locations.
Exception: Occasional transverse crossing of the corridors by supply piping that is enclosed within the corridor need not comply with Section 1406.2.1.1 through Section 1406.2.1.6.
1406.3 Special Requirements for HPP Gases. In addition to other requirements of this section, HPP gases shall comply with this subsection and the fire code.
1406.3.1 Special Provisions. Where HPP supply gas is carried in pressurized piping, a fail-safe system shall shut off flow due to a rupture in the piping. Where the piping originates from outside the building, the valve shall be located outside the building as close to the bulk source as practical.
1406.3.2 Piping and Tubing Installation. Piping and tubing shall be installed in accordance with approved standards. Supply piping for hazardous production materials having a health hazard ranking of 3 or 4 shall have welded connections throughout, unless an exhausted enclosure is provided.
Exception: Material that is incompatible with ferrous piping shall be permitted to be installed in nonmetallic piping with approved connections.
CMC § 1405.2 High relevance — show source text
Excavations required for the installation of underground piping shall be kept open until such time as the piping has been inspected and approved. Where such piping is covered or concealed before such approval, it shall be exposed upon the direction of the Authority Having Jurisdiction.
1405.2 Required Inspections. The Authority Having Jurisdiction shall make the following inspections and shall either approve that portion of the work as completed or shall notify the permit holder wherein the same fails to be in accordance with this code.
1405.2.1 Rough Piping Inspection. This inspection shall be made after process piping authorized by the permit has been installed and before piping has been cov
ered or concealed. This inspection shall include a determination that the piping size, material, and installation are in accordance with the requirements of this code.
1405.2.2 Final Piping Inspection. This inspection shall be made after piping authorized by the permit has been installed and after portions thereof that are to be covered or concealed are so concealed. This inspection shall include a pressure test, at which time the piping shall stand a pressure of not less than one-and-one-half times the maximum designed operating pressure where hydraulic testing is conducted or 110 percent where testing is conducted pneumatically. Test pressures shall be held for a length of time satisfactory to the Authority Having Jurisdiction, but in no case for less than 30 minutes with no perceptible drop in pressure. HPM drain, waste, and vent piping shall be tested in accordance with the plumbing code. Tests shall be made in the presence of the Authority Having Jurisdiction. Necessary apparatus for conducting tests shall be furnished by the permit holder.
1405.3 Other Inspections. In addition to the inspections required by this section, the Authority Having Jurisdiction shall be permitted to require a special inspector, as specified in the building code, during installation of piping systems. In cases where the work authorized was installed in accordance with plans and specifications prepared by a registered design professional, the Authority Having Jurisdiction shall be permitted to require a final signed report stating that the work was installed in accordance with approved plans and specifications and the applicable provisions of this chapter.
1406.0 Pipe, Tubing, and Fittings.
1406.1 General. Process pipe, tubing, and fittings shall comply with ASME B31.3 and shall be installed in accordance with the manufacturer’s installation instructions. Materials shall be rated for the operating temperatures and pressures of the system, and shall be compatible with the type of liquid.
1406.2 Hazardous Process Piping (HPP). HPP supply piping or tubing in service corridors shall be exposed to view. HPP piping shall be identified in accordance with nationally recognized standards to indicate the material being transported. Liquid HPP piping shall have an approved means for directing spilled materials to an approved containment or drainage system.
Liquid HPP waste or drainage systems shall be installed in accordance with the plumbing code.
1406.2.1 Installation in Exit Corridors and Above Other Occupancies. Hazardous process supply pipe shall not be located within exit corridors, within a portion of a means of egress required to be enclosed in fire-resistive construction, or in concealed spaces in or above
2025 CALIFORNIA MECHANICAL CODE 335
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
PROCESS PIPING
areas not classified as Group H Occupancies, except as permitted by this subsection.
CMC § 415.9 High relevance — show source text
[F] 415.9 Group H-2. Occupancies in Group H-2 shall be constructed in accordance with Sections 415.9.1 through 415.9.3 and the California Fire Code.
[F] 415.9.1 Flammable and combustible liquids. The storage, handling, processing and transporting of flammable and combustible liquids in Group H-2 and H-3 occupancies shall be in accordance with Sections 415.9.1.1 through 415.9.1.9, the California Mechanical Code and the California Fire Code .
[F] 415.9.1.1 Mixed occupancies. Where the storage tank area is located in a building of two or more occupancies and the quantity of liquid exceeds the maximum allowable quantity for one control area, the use shall be completely separated from adjacent occupancies in accordance with the requirements of Section 508.4.
[F] 415.9.1.1.1 Height exception. Where storage tanks are located within a building not more than one story above grade plane, the height limitation of Section 504 shall not apply for Group H.
[F] 415.9.1.2 Tank protection. Storage tanks shall be noncombustible and protected from physical damage. Fire barriers or horizontal assemblies or both around the storage tanks shall be permitted as the method of protection from physical damage.
[F] 415.9.1.3 Tanks. Storage tanks shall be approved tanks conforming to the requirements of the California Fire Code .
[F] 415.9.1.4 Leakage containment. A liquid-tight containment area compatible with the stored liquid shall be provided. The method of spill control, drainage control and secondary containment shall be in accordance with the California Fire Code .
Exception: Rooms where only double-wall storage tanks conforming to Section 415.9.1.3 are used to store Class I, II and IIIA flammable and combustible liquids shall not be required to have a leakage containment area.
[F] 415.9.1.5 Leakage alarm. An approved automatic alarm shall be provided to indicate a leak in a storage tank and room. The alarm shall sound an audible signal, 15 dBa above the ambient sound level, at every point of entry into the room in which the leaking storage tank is located. An approved sign shall be posted on every entry door to the tank storage room indicating the potential hazard of the interior room environment, or the sign shall state, “WARNING, WHEN ALARM SOUNDS, THE ENVIRONMENT WITHIN THE ROOM MAY BE HAZARDOUS.” The leakage alarm shall be supervised in accordance with Chapter 9 to transmit a trouble signal.
[F] 415.9.1.6 Tank vent. Storage tank vents for Class I, II or IIIA liquids shall terminate to the outdoor air in accordance with the California Fire Code .
[F] 415.9.1.7 Room ventilation. Storage tank areas storing Class I, II or IIIA liquids shall be provided with mechanical ventilation. The mechanical ventilation system shall be in accordance with the California Mechanical Code and the California Fire Code .
[F] 415.9.1.8 Explosion venting. Where Class I liquids are being stored, explosion venting shall be provided in accordance with the California Fire Code .
CMC § 5004.2.2.1 High relevance — show source text
STORAGE**|INDOOR STORAGE|OUTDOOR STORAGE|OUTDOOR STORAGE| |MATERIAL|MATERIAL|Solids|Liquids|Solids|Liquids| |Pyrophorics|Pyrophorics|Not Required|Required|Not Required|Required| |Unstable (reactives)|Class 4|Required|Required|Required|Required| |Unstable (reactives)|Class 3|Class 3|Class 3|Class 3|Class 3| |Unstable (reactives)|Class 2|Class 2|Class 2|Class 2|Class 2| |Unstable (reactives)|Class 1|Not Required|Not Required|Not Required|Not Required| |Water reactives|Class 3|Required|Required|Required|Required| |Water reactives|Class 2|Class 2|Class 2|Class 2|Class 2| |Water reactives|Class 1|Not Required|Not Required|Not Required|Not Required| |2. Health-hazard materials|2. Health-hazard materials|2. Health-hazard materials|2. Health-hazard materials|2. Health-hazard materials|2. Health-hazard materials| |Corrosives|Corrosives|Not Required|Required|Not Required|Required| |Highly toxics|Highly toxics|Required|Required|Required|Required| |Toxics|Toxics|Toxics|Toxics|Toxics|Toxics|
5004.2.2.1 Containment and drainage methods. The building, room or area shall contain or drain the hazardous materials and fire protection water through the use of one of the following methods:
Liquid-tight sloped or recessed floors in indoor locations or similar areas in outdoor locations.
Liquid-tight floors in indoor locations or similar areas in outdoor locations provided with liquid-tight raised or recessed sills or dikes.
Sumps and collection systems.
Drainage systems leading to an approved location.
Other approved engineered systems.
5004.2.2.2 Incompatible materials. Incompatible materials used in open systems shall be separated from each other in the secondary containment system.
5004.2.2.3 Indoor design. Secondary containment for indoor storage areas shall be designed to contain a spill from the largest vessel plus the design flow volume of fire protection water calculated to discharge from the fire-extinguishing system over the minimum required system design area or area of the room or area in which the storage is located, whichever is smaller. The containment capacity shall be designed to contain the flow for a period of 20 minutes.
5004.2.2.4 Outdoor design. Secondary containment for outdoor storage areas shall be designed to contain a spill from the largest individual vessel. If the area is open to rainfall, secondary containment shall be designed to include the volume of a 24hour rainfall as determined by a 25-year storm and provisions shall be made to drain accumulations of groundwater and rainwater.
5004.2.2.5 Monitoring. An approved monitoring method shall be provided to detect hazardous materials in the secondary containment system. The monitoring method is allowed to be visual inspection of the primary or secondary containment, or other approved means. Where secondary containment is subject to the intrusion of water, a monitoring method for detecting water shall be provided. Where monitoring devices are provided, they shall be connected to approved visual or audible alarms.
CMC § 57-33 High relevance — show source text
2025 CALIFORNIA FIRE CODE 57-33
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
FLAMMABLE AND COMBUSTIBLE LIQUIDS
5705.3.7.6.1 Ventilation. Closed systems designed to be opened as part of normal operations shall be provided with ventilation in accordance with Section 5705.3.7.5.1.
5705.3.7.6.2 Explosion control. Explosion control shall be provided where an explosive environment can occur as a result of the mixing or use process. Explosion control shall be designed in accordance with Section 911.
Exception: Where process vessels are designed to contain fully the worst-case explosion anticipated within the vessel under process conditions considering the most likely failure.
5705.3.7.6.3 Spill control and secondary containment. Spill control shall be provided in accordance with Section 5703.4 where flammable or combustible liquids are dispensed into containers exceeding a 1.3-gallon (5 L) capacity or mixed or used in open containers or systems exceeding a 5.3-gallon (20 L) capacity. Spill control and secondary containment shall be provided in accordance with Section 5703.4 where the capacity of an individual container exceeds 55 gallons (208 L) or the aggregate capacity of multiple containers or tanks exceeds 1,000 gallons (3785 L).
5705.3.8 Use, dispensing and handling outside of buildings. Outside use, dispensing and handling shall be in accordance with Sections 5705.3.8.1 through 5705.3.8.4.
Dispensing of liquids into motor vehicle fuel tanks at motor fuel-dispensing facilities shall be in accordance with Chapter 23.
5705.3.8.1 Spill control. Outside use, dispensing and handling areas shall be provided with spill control as set forth in Section 5703.4.
5705.3.8.2 Location on property. Dispensing activities that exceed the quantities set forth in Table 5705.3.8.2 shall not be conducted within 15 feet (4572 mm) of buildings or combustible materials or within 25 feet (7620 mm) of building openings, lot lines, public streets, public alleys or public ways. Dispensing activities that exceed the quantities set forth in Table 5705.3.8.2 shall not be conducted within 15 feet (4572 mm) of storage of Class I, II or III liquids unless such liquids are stored in tanks that are listed and labeled as 2-hour protected tank assemblies in accordance with UL 2085.
Exceptions:
- The requirements shall not apply to areas where only the following are dispensed: Class III liquids; liquids that are heavier than water; water-miscible liquids; and liquids with viscosities greater than 10,000 centipoise (cp) (10 Pa × s).
- Flammable and combustible liquid dispensing in refineries, chemical plants, process facilities, gas and crude oil production facilities and oil-blending and packaging facilities, terminals and bulk plants.
CMC § 5704.3.7.2.1 High relevance — show source text
5704.3.7.2.1 Mixed storage. Where two or more classes of liquids are stored in a pile or rack section, both of the following shall apply:
- The quantity in that pile or rack shall not exceed the smallest of the maximum quantities for the classes of liquids stored in accordance with Table 5704.3.6.3(2) or 5704.3.6.3(3).
- The height of storage in that pile or rack shall not exceed the smallest of the maximum heights for the classes of liquids stored in accordance with Table 5704.3.6.3(2) or 5704.3.6.3(3).
5704.3.7.2.2 Separation and aisles. Piles shall be separated from each other by not less than 4-foot (1219 mm) aisles. Aisles shall be provided so that all containers are 20 feet (6096 mm) or less from an aisle. Where the storage of liquids is on racks, a minimum 4-foot-wide (1219 mm) aisle shall be provided between adjacent rows of racks and adjacent storage of liquids. Main aisles shall be not less than 8 feet (2438 mm) wide.
Additional aisles shall be provided for access to doors, required windows and ventilation openings, standpipe connections, mechanical equipment and switches. Such aisles shall be not less than 3 feet (914 mm) in width, unless greater widths are required for separation of piles or racks, in which case the greater width shall be provided.
5704.3.7.2.3 Stabilizing and supports. Containers and piles shall be separated by pallets or dunnage to provide stability and to prevent excessive stress to container walls. Portable tanks stored over one tier shall be designed to nest securely without dunnage.
Requirements for portable tank design shall be in accordance with Chapters 9 and 12 of NFPA 30. Shelving, racks, dunnage, scuffboards, floor overlay and similar installations shall be of noncombustible construction or of wood not less than a 1-inch (25 mm) nominal thickness. Adequate material-handling equipment shall be available to handle tanks safely at upper tier levels.
5704.3.7.3 Spill control and secondary containment. Liquid storage rooms shall be provided with spill control and secondary containment in accordance with Section 5004.2.
5704.3.7.4 Ventilation. Liquid storage rooms shall be ventilated in accordance with Section 5004.3.
5704.3.7.5 Fire protection. Fire protection for liquid storage rooms shall comply with Sections 5704.3.7.5.1 and 5704.3.7.5.2.
5704.3.7.5.1 Fire-protection systems. Liquid storage rooms shall be protected by automatic sprinkler systems installed in accordance with Chapter 9 and Tables 5704.3.6.3(4) through 5704.3.6.3(7) and Table 5704.3.7.5.1. In-rack sprinklers shall also comply with NFPA 13.
Automatic foam-water systems and automatic aqueous film-forming foam (AFFF) water sprinkler systems shall not be used except where approved.
CMC § 5004.2 High relevance — show source text
5004.2 Spill control and secondary containment for liquid and solid hazardous materials. Rooms, buildings or areas used for the storage of liquid or solid hazardous materials shall be provided with spill control and secondary containment in accordance with Sections 5004.2.1 through 5004.2.3.
Exception: Outdoor storage of containers on approved containment pallets in accordance with Section 5004.2.3.
5004.2.1 Spill control for hazardous material liquids. Rooms, buildings or areas used for the storage of hazardous material liquids in individual vessels having a capacity of more than 55 gallons (208 L), or in which the aggregate capacity of multiple vessels exceeds 1,000 gallons (3785 L), shall be provided with spill control to prevent the flow of liquids to adjoining areas. Floors in indoor locations and similar surfaces in outdoor locations shall be constructed to contain a spill from the largest single vessel by one of the following methods:
Liquid-tight sloped or recessed floors in indoor locations or similar areas in outdoor locations.
Liquid-tight floors in indoor locations or similar areas in outdoor locations provided with liquid-tight raised or recessed sills or dikes.
Sumps and collection systems.
Other approved engineered systems.
Except for surfacing, the floors, sills, dikes, sumps and collection systems shall be constructed of noncombustible material, and the liquid-tight seal shall be compatible with the material stored. Where liquid-tight sills or dikes are provided, they are not required at perimeter openings having an open-grate trench across the opening that connects to an approved collection system.
5004.2.2 Secondary containment for hazardous material liquids and solids. Where required by Table 5004.2.2, buildings, rooms or areas used for the storage of hazardous materials liquids or solids shall be provided with secondary containment in accordance with this section where the capacity of an individual vessel or the aggregate capacity of multiple vessels exceeds both of the following:
- Liquids: Capacity of an individual vessel exceeds 55 gallons (208 L) or the aggregate capacity of multiple vessels exceeds 1,000 gallons (3785 L).
- Solids: Capacity of an individual vessel exceeds 550 pounds (250 kg) or the aggregate capacity of multiple vessels exceeds 10,000 pounds (4540 kg).
TABLE 5004.2.2—REQUIRED SECONDARY CONTAINMENT—HAZARDOUS MATERIAL SOLIDS AND LIQUIDS STORAGE Col2 Col3 Col4 Col5 Col6 MATERIAL MATERIAL INDOOR STORAGE INDOOR STORAGE OUTDOOR STORAGE OUTDOOR STORAGE MATERIAL MATERIAL Solids Liquids Solids Liquids 1. Physical-hazard materials 1. Physical-hazard materials 1. Physical-hazard materials 1. Physical-hazard materials 1. Physical-hazard materials 1. Physical-hazard materials Combustible liquids Class II Not Applicable See Chapter 57 Not Applicable See Chapter 57 Combustible liquids Class IIIA Class IIIA See Chapter 57 See Chapter 57 See Chapter 57 Combustible liquids Class IIIB Class IIIB See Chapter 57 See Chapter 57 See Chapter 57 Cryogenic CMC § 5703.2.1 High relevance — show source text
5703.2.1 Portable fire extinguishers and hose lines. Portable fire extinguishers shall be provided in accordance with Section 906. Hose lines shall be provided in accordance with Section 905.
5703.3 Site assessment. In the event of a spill, leak or discharge from a tank system, a site assessment shall be completed by the owner or operator of such tank system if the fire code official determines that a potential fire or explosion hazard exists. Such site assessments shall be conducted to ascertain potential fire hazards and shall be completed and submitted to the fire department within a time period established by the fire code official, not to exceed 60 days.
5703.4 Spill control and secondary containment. Where the maximum allowable quantity per control area is exceeded, and where required by Section 5004.2, rooms, buildings or areas used for storage, dispensing, use, mixing or handling of Class I, II and IIIA liquids shall be provided with spill control and secondary containment in accordance with Section 5004.2.
5703.4.1 Spill control and secondary containment for tanks in underground areas. Tanks in underground areas and associated piping systems shall be provided with spill control and secondary containment that are designed and constructed as outlined in Section 5004.2, except as modified by Section 5703.6.2.2.
5703.5 Labeling and signage. The fire code official is authorized to require warning signs for the purpose of identifying the hazards of storing or using flammable liquids. Signage for identification and warning such as for the inherent hazard of flammable liquids or smoking shall be provided in accordance with this chapter and Sections 5003.5 and 5003.6.
5703.5.1 Style. Warning signs shall be of a durable material. Signs warning of the hazard of flammable liquids shall have white lettering on a red background and shall read: “DANGER—FLAMMABLE LIQUIDS.” Letters shall be not less than 3 inches (76 mm) in height and [1] / 2 inch (12.7 mm) in stroke.
5703.5.2 Location. Signs shall be posted in locations as required by the fire code official. Piping containing flammable liquids shall be identified in accordance with ASME A13.1.
5703.5.3 Warning labels. Individual containers, packages and cartons shall be identified, marked, labeled and placarded in accordance with federal regulations and applicable state laws.
5703.5.4 Identification. Color coding or other approved identification means shall be provided on each loading and unloading riser for flammable or combustible liquids to identify the contents of the tank served by the riser.
5703.6 Piping systems. Piping systems, and their component parts, for flammable and combustible liquids shall be in accordance with Sections 5703.6.1 through 5703.6.11.
57-6 2025 CALIFORNIA FIRE CODE
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FLAMMABLE AND COMBUSTIBLE LIQUIDS
5703.6.1 Nonapplicability. The provisions of Section 5703.6 shall not apply to gas or oil well installations; piping that is integral to stationary or portable engines, including aircraft, watercraft and motor vehicles; and piping in connection with boilers and pressure vessels regulated by the California Mechanical Code .
CMC § 5004.2.2.2 Medium relevance — show source text
- Sumps and collection systems.
- Drainage systems leading to an approved location.
- Other approved engineered systems.
5004.2.2.2 Incompatible materials. Incompatible materials used in open systems shall be separated from each other in the secondary containment system.
5004.2.2.3 Indoor design. Secondary containment for indoor storage areas shall be designed to contain a spill from the largest vessel plus the design flow volume of fire protection water calculated to discharge from the fire-extinguishing system over the minimum required system design area or area of the room or area in which the storage is located, whichever is smaller. The containment capacity shall be designed to contain the flow for a period of 20 minutes.
5004.2.2.4 Outdoor design. Secondary containment for outdoor storage areas shall be designed to contain a spill from the largest individual vessel. If the area is open to rainfall, secondary containment shall be designed to include the volume of a 24hour rainfall as determined by a 25-year storm and provisions shall be made to drain accumulations of groundwater and rainwater.
5004.2.2.5 Monitoring. An approved monitoring method shall be provided to detect hazardous materials in the secondary containment system. The monitoring method is allowed to be visual inspection of the primary or secondary containment, or other approved means. Where secondary containment is subject to the intrusion of water, a monitoring method for detecting water shall be provided. Where monitoring devices are provided, they shall be connected to approved visual or audible alarms.
5004.2.2.6 Drainage system design. Drainage systems shall be in accordance with the California Plumbing Code and all of the following:
- The slope of floors to drains in indoor locations, or similar areas in outdoor locations shall be not less than 1 percent.
- Drains from indoor storage areas shall be sized to carry the volume of the fire protection water as determined by the design density discharged from the automatic fire-extinguishing system over the minimum required system design area or area of the room or area in which the storage is located, whichever is smaller.
- Drains from outdoor storage areas shall be sized to carry the volume of the fire flow and the volume of a 24-hour rainfall as determined by a 25-year storm.
- Materials of construction for drainage systems shall be compatible with the materials stored.
- Incompatible materials used in open systems shall be separated from each other in the drainage system.
- Drains shall terminate in an approved location away from buildings, valves, means of egress, fire access roadways, adjoining property and storm drains.
5004.2.3 Containment pallets. Where used as an alternative to spill control and secondary containment for outdoor storage in accordance with the exception in Section 5004.2, containment pallets shall comply with all of the following:
- A liquid-tight sump with access for visual inspection shall be provided.
- The sump shall be designed to contain not less than 66 gallons (250 L).
2025 CALIFORNIA FIRE CODE 50-23
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HAZARDOUS MATERIALS—GENERAL PROVISIONS
- Exposed surfaces shall be compatible with material stored.
- Containment pallets shall be protected to prevent collection of rainwater within the sump.
5004.3 Ventilation. Indoor storage areas and storage buildings shall be provided with mechanical exhaust ventilation or natural ventilation where natural ventilation can be shown to be acceptable for the materials as stored.
CMC § 2306.3 Medium relevance — show source text
2306.3 Security. Above-ground tanks for the storage of liquid motor fuels shall be safeguarded from public access or unauthorized entry in an approved manner.
2306.4 Physical protection. Guard posts complying with Section 312 or other approved means shall be provided to protect aboveground tanks against impact by a motor vehicle unless the tank is listed as a protected above-ground tank with vehicle impact protection.
2306.5 Secondary containment. Above-ground tanks shall be provided with drainage control or diking in accordance with Chapter 57. Drainage control and diking is not required for listed secondary containment tanks. Secondary containment systems shall be monitored either visually or automatically. Enclosed secondary containment systems shall be provided with emergency venting in accordance with Section 2306.6.2.5.
2306.6 Piping, valves, fittings and ancillary equipment for use with flammable or combustible liquids. The design, fabrication, assembly, testing and inspection of piping, valves, fittings and ancillary equipment for use with flammable or combustible liquids shall be in accordance with Chapter 57 and Sections 2306.6.1 through 2306.6.3.
2306.6.1 Protection from damage. Piping shall be located such that it is protected from physical damage.
2306.6.2 Piping, valves, fittings and ancillary equipment for above-ground tanks for Class I, II and III liquids. Piping, valves, fittings and ancillary equipment for above-ground tanks storing Class I, II and III liquids shall comply with Sections 2306.6.2.1 through 2306.6.2.6.
2306.6.2.1 Tank openings. Tank openings for above-ground tanks shall be through the top only.
2306.6.2.2 Fill-pipe connections. The fill pipe for above-ground tanks shall be provided with a means for making a direct connection to the tank vehicle’s fuel-delivery hose so that the delivery of fuel is not exposed to the open air during the filling operation. Where any portion of the fill pipe exterior to the tank extends below the level of the top of the tank, a check valve shall be installed in the fill pipe not more than 12 inches (305 mm) from the fill-hose connection.
2306.6.2.3 Overfill protection. Overfill protection shall be provided for above-ground flammable and combustible liquid storage tanks in accordance with Sections 5704.2.7.5.8 and 5704.2.9.7.5.
2306.6.2.4 Siphon prevention. An approved antisiphon method shall be provided in the piping system to prevent flow of liquid by siphon action.
2306.6.2.5 Emergency relief venting. Above-ground storage tanks, tank compartments and enclosed secondary containment spaces shall be provided with emergency relief venting in accordance with Chapter 57.
2306.6.2.6 Spill containers. A spill container having a capacity of not less than 5 gallons (19 L) shall be provided for each fill connection. For tanks with a top fill connection, spill containers shall be noncombustible and shall be fixed to the tank and
2025 CALIFORNIA FIRE CODE 23-7
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MOTOR FUEL-DISPENSING FACILITIES AND REPAIR GARAGES
equipped with a manual drain valve that drains into the primary tank. For tanks with a remote fill connection, a portable spill container is allowed.
CMC § 5704.3.8 Medium relevance — show source text
5704.3.8 Liquid storage warehouses. Buildings used for storage of flammable or combustible liquids in quantities exceeding those set forth in Section 5704.3.4 for control areas and Section 5704.3.7 for liquid storage rooms shall comply with Sections 5704.3.8.1 through 5704.3.8.5 and shall be constructed and separated as required by the California Building Code .
5704.3.8.1 Quantities and storage arrangement. The total quantities of liquids in a liquid storage warehouse shall not be limited. The arrangement of storage shall be in accordance with Table 5704.3.6.3(2) or 5704.3.6.3(3).
5704.3.8.1.1 Mixed storage. Mixed storage shall be in accordance with Section 5704.3.7.2.1.
5704.3.8.1.2 Separation and aisles. Separation and aisles shall be in accordance with Section 5704.3.7.2.2.
5704.3.8.2 Spill control and secondary containment. Liquid storage warehouses shall be provided with spill control and secondary containment as set forth in Section 5004.2.
5704.3.8.3 Ventilation. Liquid storage warehouses storing containers greater than 5 gallons (19 L) in capacity shall be ventilated at a rate of not less than 0.25 cfm per square foot (0.00127 m [3] /s × m [2] ) of floor area over the storage area.
5704.3.8.4 Automatic sprinkler systems. Liquid storage warehouses shall be protected by automatic sprinkler systems installed in accordance with Chapter 9 and Tables 5704.3.6.3(4) through 5704.3.6.3(7) and Table 5704.3.7.5.1, or Sections 16.4.1 through 16.4.3, 16.5.1 through 16.5.3.12, and Figures 16.4.1(a) through 16.4.1(c) and Tables 16.5.3.1 through 16.5.3.12 of NFPA 30. In-rack sprinklers shall also comply with NFPA 13.
Automatic foam-water systems and automatic AFFF water sprinkler systems shall not be used except where approved.
Protection criteria developed from fire modeling or full-scale fire testing conducted at an approved testing laboratory are allowed in lieu of the protection as shown in Tables 5704.3.6.3(2) through 5704.3.6.3(7) and Table 5704.3.7.5.1 where approved. 5704.3.8.5 Warehouse hose lines. In liquid storage warehouses, either 1 [1] / 2 -inch (38 mm) lined or 1-inch (25 mm) hard rubber hose lines shall be provided in sufficient number to reach all liquid storage areas and shall be in accordance with Section 903 or 905.
5704.4 Outdoor storage of containers and portable tanks. Storage of flammable and combustible liquids in closed containers and portable tanks outside of buildings shall be in accordance with Section 5703 and Sections 5704.4.1 through 5704.4.8. Capacity limits for containers and portable tanks shall be in accordance with Section 5704.3.
5704.4.1 Plans. Storage shall be in accordance with approved plans.
Frequently asked questions
Can I use the 1‑hour fire‑rated corridor enclosure as the receptor for leaked liquid HPP?
No. The CMC explicitly states the 1 hour enclosure shall not be used as part of the receptor when piping or tubing transports HPP liquids (see § 1406.2.1.3).
Does the CMC tell me the exact label style or colors to use for HPP piping?
No. § 1406.2 requires identification “in accordance with nationally recognized standards,” but it does not list a specific standard or style. Confirm with the AHJ or the referenced standards adopted by your jurisdiction for the required marking convention.
Does the CMC specify receptor size or sump capacity?
No. The CMC requires a receptor that collects discharge or leakage and drains to an approved location (see § 1406.2.1.3), but it does not prescribe numeric receptor volumes or drain sizes. Sizing and drainage details must follow the plumbing code and AHJ requirements.
If HPP piping crosses a corridor only occasionally and is enclosed, do the corridor installation rules apply?
There is an exception for occasional transverse crossings enclosed within the corridor: such crossings need not comply with the corridor installation subsections (1406.2.1.1–1406.2.1.6). Verify applicability with the AHJ.
Where must receptor drainage terminate?
The CMC requires drainage to an approved location and that liquid HPP waste/drainage systems be installed per the plumbing code (see § 1406.2). The exact approved termination point is subject to AHJ approval and applicable plumbing/fire code limits.
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