CMC · California Mechanical Code
What are the hanger, support, and seismic restraint requirements for piping and tubing?
For homeowners: the CMC requires all pipes and tubes be hung and anchored so they don’t sag or overstress connections, with minimum hanger rod sizes listed in Table 313.6 and support spacing set by Table 313.3; seismic bracing must follow the California Building Code (check your project’s Code tables and AHJ for the exact spacings and seismic details).
Last reviewed: July 6, 2026
What the code requires — plain English
- Piping and tubing must be supported and anchored per the California Mechanical Code (follow the Code, the manufacturer's instructions, and the Authority Having Jurisdiction). Seismic restraints are required and are to follow the California Building Code (the CMC defers seismic design to the building code). See § 313.1, § 313.3, and § 313.6 for the controlling references.
The single most important rule: support pipe and tubing so it stays aligned and carries its weight safely, and follow the building code for seismic bracing.
Requirements in detail
1) General support and seismic scope (what the CMC actually says)
- Piping, tubing, appliances, and appurtenances must be supported in accordance with this code, the manufacturer’s installation instructions, and the Authority Having Jurisdiction. Seismic restraints are required to comply with the building code. See § 313.1.
- Hangers, supports, and anchors must be of sufficient strength to support the pipe/tube and its contents; piping/tubing must be isolated from incompatible materials. See § 313.2.
2) Suspended piping spacing
- Suspended pipe and tubing must be supported at intervals not to exceed the distances shown in Table 313.3 (the CMC mandates use of that table). See § 313.3.
- NOTE: The numeric spacing values in Table 313.3 were not present in the uploaded CMC excerpts I was given. The Code text points you to Table 313.3 for the exact spacing; consult the printed/authorized Code or your AHJ to get the table values.
3) Minimum hanger rod sizes (decision‑critical dimensions)
- The CMC prescribes minimum hanger rod diameters by pipe/tube nominal size in Table 313.6 and requires hanger rods to be not smaller than the table values. See § 313.6.
| Pipe / Tube nominal size (in) | Minimum hanger rod size (in) | Code reference |
|---|---|---|
| 1/2 – 4 | 3/8 | § 313.6 |
| 5 – 8 | 1/2 | § 313.6 |
| 10 – 12 | 5/8 | § 313.6 |
(For SI: 1 in = 25.4 mm.)
4) Seismic restraints — where the CMC sends you
- The CMC requires seismic restraints per the building code (see § 313.1). That means the specific seismic-bracing rules and exemptions live in Title 24/California Building Code (which incorporates/edits ASCE 7).
- The California Building Code (modifying ASCE 7 provisions) contains additional provisions for piping and tubing systems that can relieve piping runs from full seismic force design when specific conditions are met — for example: use of flexible connections or expansion loops, trapeze or individual rod hangers of specified diameters and lengths ≤ 12 in, and limits on weight per hanger or trapeze. See the Building Code replacement/AMENDMENT to ASCE 7, Section 13.6.7.3.
Important thresholds in those building-code provisions (examples you will see in the Building Code text):
- Rod diameters: 3/8 in or 1/2 in (10 mm or 13 mm).
- Maximum hanger length from pipe to structure for these exceptions: 12 in (305 mm).
- Weight limits that affect the exception: a single hanger ≤ 50 lb (220 N); a trapeze ≤ 100 lb (445 N).
- Pipe size limits in high seismic categories (examples in the amendment): where Ip > 1.0 in SD C/D/E/F, nominal pipe size limitations apply (e.g., 1 in or 3 in limits depending on Ip and SD). See the Building Code modifications.
Because § 313.1 directs seismic restraint to the building code, always check the Building Code/ASCE 7 text used by your project for the full seismic design/exception rules and, when applicable, coordinate seismic detailing (flexible connectors, anchors, expansion loops) with the structural engineer and AHJ.
Exceptions & special cases
- Gas piping has its own hanger/spacing rules (see the gas‑piping support spacing tables referenced in the Code — Table 1310.3.5.1 / Table 1210.3.5.1 depending on the Code part). The CMC points to those gas‑specific tables for spacing and requires supports suitable for the system. See § 313.7 and Table 1310.3.5.1.
- Underground piping: the CMC requires piping in the ground be laid on a firm bed for its entire length or otherwise as approved (see § 313.5).
- Continuous-support systems and specialty tubing (PEX, medical, process piping, etc.) may have their own support rules elsewhere in the Code or in referenced standards — consult the applicable section or standard (examples are in the Plumbing Code and process-piping sections).
Common mistakes to avoid
- Assuming any rod/hanger is acceptable — the CMC sets minimum hanger rod sizes in Table 313.6; using a smaller rod violates § 313.6.
- Forgetting that the CMC defers seismic design to the building code — seismic bracing only meets § 313.1 when it follows the Building Code/ASCE 7 rules. Don’t assume “standard” hangers are adequate without checking the seismic rules and any exceptions.
- Using incompatible hanger materials that contact the pipe (the Code requires isolation from incompatible materials per § 313.2).
- Not allowing for thermal expansion/contraction when installing fixed anchors and hangers — supports must not block free movement between anchors. (Related requirement appears in gas‑piping and other Code sections.)
- Applying seismic exceptions from the Building Code incorrectly (e.g., longer hanger rods, heavier trapeze loads, or larger pipe sizes than those allowed by the Building Code exceptions). Always verify the exact numeric limits in the Building Code text.
Worked example — apply the rule with numbers
Scenario: You are suspending a run of 2‑inch (nominal) chilled‑water steel pipe in a non‑hazardous commercial building located in a seismic region. You plan to support the run on individual rod hangers.
Steps and Code grounding:
- Minimum hanger rod size — 2 in pipe falls in 1/2 – 4 in bracket in Table 313.6; minimum rod = 3/8 in. Use at least 3/8‑inch threaded rod. § 313.6.
- Support spacing — the CMC requires spacing per Table 313.3 (§ 313.3). Because the uploaded excerpts do not include the numeric Table 313.3 values, you must consult the printed Code or AHJ to get the exact support spacing for 2‑in steel pipe. Do not invent spacing; follow Table 313.3.
- Seismic considerations — § 313.1 tells you seismic restraints are per the Building Code. To determine whether the run needs full seismic design or is eligible for the Building Code exception, check the Building Code (ASCE 7 modification) conditions:
- If you provide flexible connections/expansion loops and supports are individual rod hangers of 3/8 in diameter and each hanger length to structure is ≤ 12 in, and the load per hanger is ≤ 50 lb, you may qualify for the “no additional seismic design” allowance in the Building Code amendment (ASCE 7 §13.6.7.3 as modified). Confirm the building code details for your seismic design category and Ip values.
Summary for this example: use at least 3/8 in rod (per § 313.6), follow Table 313.3 for spacing (consult Code/AHJ), and confirm seismic exception eligibility and any required flexible connectors with the Building Code provisions (per § 313.1).
Related provisions (CMC and cross‑references)
- § 313.1 — General hangers/supports; seismic restraint defers to building code.
- § 313.2 — Materials: hangers/supports/anchors strength and isolation from incompatible materials.
- § 313.3 — Suspended piping supported at intervals in Table 313.3.
- § 313.6 — Hanger rod minimum sizes (Table 313.6).
- § 313.7 — Gas piping support rules (references gas support spacing table).
- Building Code / ASCE 7 modifications (see the California Building Code replacement of ASCE 7 §13.6.7.3 for additional provisions and exceptions for piping/tubing seismic design). (Building Code / ASCE 7 modifications)
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 312.0 High relevance — show source text
312.0 Plumbing Connections. 312.1 General. Water supply, sanitary drainage, and backflow protection shall be in accordance with the California Plumbing Code .
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, appliances, and appurtenances shall be supported in accordance with this code, the manufacturer’s installation instructions, and in accordance with the Authority Having Jurisdiction. Seismic restraints shall be in accordance with the building code. 313.2 Material. Hangers, supports, and anchors shall be of sufficient strength to support the weight of the pipe or tubing and its contents. Piping or tubing shall be isolated from incompatible materials.
313.3 Suspended Piping. Suspended piping or tubing shall be supported at intervals not to exceed those shown in Table 313.3.
313.4 Alignment. Piping or tubing shall be supported in such a manner as to maintain its alignment and prevent sagging.
313.5 Underground Installation. Piping or tubing in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 302.0.
313.6 Hanger Rod Sizes. Hanger rod sizes shall be not smaller than those shown in Table 313.6.
TABLE 313.6
HANGER ROD SIZES
PIPE AND TUBE SIZE
(inches)ROD SIZES
(inches)
1⁄2 - 43⁄8
5 - 81⁄2
10 - 125⁄8 For SI units: 1 inch = 25.4 mm
313.7 Gas Piping. Gas piping shall be supported by metal straps or hooks at intervals not to exceed those shown in Table 1310.3.5.1.
314.0 Balancing.
314.1 General. Heating, ventilating, and air-conditioning systems (including hydronic systems) shall be balanced in accordance with one of the following methods:
TABLE 313.6
HANGER ROD SIZES
(1) AABC National Standards for Total System Balance
(2) ACCA Manual B
(3) ASHRAE 111
(4) NEBB Procedural Standards for Testing Adjusting Balancing of Environmental Systems
(5) SMACNA HVAC Systems Testing, Adjusting, and Balancing
315.0 Louvers in Hurricane Prone Regions.
315.1 General. Louvers located in areas within hurricane prone regions that are within 1 mile (2 km) of the coastal mean high water line where the basic wind speed is 110 miles per hour (mi/h) (49.2 m/s) or more; or portions of hurricane-prone regions where the basic wind speed is 120 mi/h (53.6 m/s) or more; or Hawaii, shall be tested in accordance with Section 315.1.1 and Section 315.1.2.
315.1.1 Testing. Louvers that protect air intake or exhaust openings shall be tested in accordance with AMCA 550 for resistance to wind-driven rain.
315.1.2 Impact Resistance Test. Upon request by the Authority Having Jurisdiction, louvers protecting intake and exhaust ventilation ducts that are not fixed in the
CMC § 0.03 High relevance — show source text
(5) A closet, bathroom, toilet room, kitchen, garage, boiler room, furnace room, or unconditioned attic.
(6) Rooms or spaces containing a fuel-burning appliance therein. Where such room or space serves as source of return-air.
Exceptions:
(1) This shall not apply to fireplaces, fireplace appliances, residential cooking appliances, direct vent appliances, enclosed furnaces, and domestic-type clothes dryers installed within the room or space.
(2) This shall not apply to a gravity-type or listed vented wall heating or cooling air system.
(3) This shall not apply to a blower-type heating or cooling air system installed in accordance with the following requirements:
(a) Where the return air is taken from a room or space having a volume exceeding 1 cubic foot (0.03 m [3] ) for each 10 Btu/h (0.003 kW) fuel input rating of fuel-burning appliances therein.
(b) Not less than 75 percent of the supply air is discharged back into the same room or space.
(c) Return-air inlets shall not be located within 10 feet (3048 mm) from an appliance firebox or draft diverter in the same enclosed room or confined space.
311.4 Return-Air Limitations. Return air from one dwelling unit shall not discharge into another dwelling unit through the heating or cooling air system.
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GENERAL REGULATIONS
311.5 California Energy Code Requirements for Res- idential Air Filtration. In mechanically ventilated residen- tial buildings, air filters shall be provided to clean outdoor air and return air prior to its delivery to occupied spaces where specified in California Energy Code Sections 150.0(m)12 and 160.2(b). The air filters shall comply with California Energy Code requirements for labeling, ventilation system design and installation, air filter efficacy, and air filter pressure drop.
312.0 Plumbing Connections. 312.1 General. Water supply, sanitary drainage, and backflow protection shall be in accordance with the California Plumbing Code .
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, appliances, and appurtenances shall be supported in accordance with this code, the manufacturer’s installation instructions, and in accordance with the Authority Having Jurisdiction. Seismic restraints shall be in accordance with the building code. 313.2 Material. Hangers, supports, and anchors shall be of sufficient strength to support the weight of the pipe or tubing and its contents. Piping or tubing shall be isolated from incompatible materials.
313.3 Suspended Piping. Suspended piping or tubing shall be supported at intervals not to exceed those shown in Table 313.3.
313.4 Alignment. Piping or tubing shall be supported in such a manner as to maintain its alignment and prevent sagging.
313.5 Underground Installation. Piping or tubing in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 302.0.
313.6 Hanger Rod Sizes. Hanger rod sizes shall be not smaller than those shown in Table 313.6.
CMC § 1.0 High relevance — show source text
and the total weight supported by any single hanger is 50 pounds (220 N) or less. In addition, the following limitations on the size of piping shall be observed: a. In structures assigned to Seismic Design Category D, E or F where I p is greater than 1.0, the nominal pipe size shall be 1 inch (25 mm) or less. b. In structures assigned to Seismic Design Category D, E or F where I p = 1.0, the nominal pipe size shall be 3 inches (80 mm) or less. 3. Pneumatic tube systems supported with trapeze assemblies using [3] / 8 -inch (10 mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the tube support point to the connection at the supporting structure and the total weight supported by any single trapeze is 100 pounds (445 N) or less. 4. Pneumatic tube systems supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, and each hanger in the run is 12 inches (305 mm) or less in length from the tube support point to the connection at the supporting structure, and the total weight supported by any single rod is 50 pounds (220 N) or less. B) Flexible connections in piping required in Section 13.6.7.3 are not required where pipe is rigidly attached to the same floor or wall that provides vertical and lateral support for the equipment, or to a fixture. C) Flexible connections in piping are required at seismic separation joints and shall be detailed to accommodate the seis- mic relative displacements at connections.
1617.12.17 ASCE 7, Section 13.6.11.1. Modify ASCE 7, Section 13.6.11.1 by adding Section 13.6.11.1.1, as follows:
13.6.11.1.1 Elevators guide rail support. The design of guide rail support bracket fastenings and the supporting structural fram- ing shall use the weight of the counterweight or maximum weight of the car plus not more than 40 percent of its rated load. The seismic forces shall be assumed to be distributed one-third to the top guiding members and two-thirds to the bottom guiding members of cars and counterweights, unless other substantiating data are provided. In addition to the requirements of ASCE 7, Section 13.6.11.1, the minimum seismic forces shall be 0.5g allowable stress design load acting in any horizontal direction.
1617.12.18 ASCE 7, Section 13.6.11.4. Replace ASCE 7, Section 13.6.11.4, as follows:
13.6.11.4 Retainer plates. Retainer plates are required at the top and bottom of the car and counterweight, except where safety devices acceptable to the enforcement agency are provided which meet all requirements of the retainer plates, including full engagement of the machined portion of the rail. The design of the car, cab stabilizers, counterweight guide rails and counter- weight frames for seismic forces shall be based on the following requirements: 1. _The seismic force shall be computed per the requirements of ASCE 7, Section 13.6.11.1.
CMC § 313.0 High relevance — show source text
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, fixtures, appliances, and appurtenances shall be supported in accordance with this code, the manufacturer’s installation instructions, and in accordance with the Authority Having Jurisdiction. Seismic restraints shall be in accordance with the building code. 313.2 Material. Hangers, supports, and anchors shall be of sufficient strength to support the weight of the pipe or tubing and its contents. Piping or tubing shall be isolated from incompatible materials. 313.3 Suspended Piping. Suspended piping shall be supported at intervals not to exceed those shown in Table 313.3. 313.4 Alignment. Piping shall be supported in such a manner as to maintain its alignment and prevent sagging. 313.5 Underground Installation. Piping in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 301.2.
313.6 Hanger Rod Sizes. Hanger rod sizes shall be not smaller than those shown in Table 313.6.
TABLE 313.6
HANGER ROD SIZES
PIPE AND TUBE SIZE
(inches)ROD SIZE
(inches)
1⁄2 – 43⁄8
5 – 81⁄2
10 – 125⁄8 For SI units: 1 inch = 25.4 mm
313.7 Gas Piping. Gas piping shall be supported by metal straps or hooks at intervals not to exceed those shown in Table 1210.3.5.1.
313.8 [OSHPD 1, 2, 3, 4 & 5] Refer to Title 24, Part 2 of the California Building Code for seismic anchorage and bracing requirements and accommodations for building displace-
ments.
314.0 Trenching, Excavation, and Backfill.
314.1 Trenches. Trenches deeper than the footing of a building or structure, and paralleling the same, shall be located not less than 45 degrees (0.79 rad) from the bottom exterior edge of the footing, or as approved in accordance with Section 301.0.
314.2 Tunneling and Driving. Tunneling and driving shall be permitted to be done in yards, courts, or driveways of a building site. Where sufficient depth is available to permit, tunnels shall be permitted to be used between open-cut trenches.
Tunnels shall have a clear height of 2 feet (610 mm) above the pipe and shall be limited in length to one-half the depth of the trench, with a maximum length of 8 feet (2438 mm). Where pipes are driven, the drive pipe shall be not less than one size larger than the pipe to be laid.
314.3 Open Trenches. Excavations required to be made for the installation of a building drainage system or part thereof, within the walls of a building, shall be open trench work and shall be kept open until the piping has been inspected, tested, and accepted.
CMC § 13.3 High relevance — show source text
or
b. The duct is supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, and each hanger in the duct run is 12 inches (305 mm) or less in length from the duct support point to the connection at the supporting structure, and the total weight supported by any single rod is 50 pounds (220 N) or less. 2. Design for the seismic forces and relative displacements of Section 13.3 shall not be required where provisions are made to avoid impact with other ducts or mechanical components or to protect the ducts in the event of such impact, the distribution system is positively attached to the structure; and HVACR ducts have a cross-sectional area of less than 6 square feet (0.557 m [2] ) and weigh 20 lb/ft (292 N/m) or less.
Components that are installed in line with the duct system and have an operating weight greater than 75 pounds (334 N), such as fans, terminal units, heat exchangers and humidifiers, shall be supported and laterally braced independent of the duct system, and such braces shall meet the force requirements of Section 13.3.1. Components that are installed in line with the duct system, have an operating weight of 75 pounds (334 N) or less, such as small terminal units, dampers, louvers and diffusers, and are otherwise not independently braced shall be positively attached with mechanical fasteners to the rigid duct on both sides. Piping and conduit attached to in-line equipment shall be provided with adequate flexibility to accommodate the seismic relative displacements of Section 13.3.2.
16-42 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
STRUCTURAL DESIGN
1617.12.16 ASCE 7, Section 13.6.7.3. Replace ASCE 7, Section 13.6.7.3 with the following:
13.6.7.3 Additional provisions for piping and tubing systems. A) Design for the seismic forces of Section 13.3 shall not be required for piping systems where flexible connections, expansion loops or other assemblies are provided to accommodate the relative displacement between component and piping, where the piping system is positively attached to the structure, and where any of the following conditions apply:
- Trapeze assemblies are supported by [3] / 8 -inch (10 mm) or [1] / 2 -inch (13-mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the pipe support point to the connection at the supporting structure, and no single pipe exceeds the diameter limits set forth in item 2b or 2 inches (50 mm) where I p is greater than 1.0 and the total weight supported by any single trapeze is 100 pounds (445 N) or less; or 2. Piping is supported by rod hangers and provisions are made to avoid impact with other structural or nonstructural components or to protect the piping in the event of such impact; or pipes are supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, where each hanger in the pipe run is 12 inches (305 mm) or less in length from the pipe support point to the connection at the supporting structure,
CMC § 1617.12.16 High relevance — show source text
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
STRUCTURAL DESIGN
1617.12.16 ASCE 7, Section 13.6.7.3. Replace ASCE 7, Section 13.6.7.3 with the following:
13.6.7.3 Additional provisions for piping and tubing systems. A) Design for the seismic forces of Section 13.3 shall not be required for piping systems where flexible connections, expansion loops or other assemblies are provided to accommodate the relative displacement between component and piping, where the piping system is positively attached to the structure, and where any of the following conditions apply:
- Trapeze assemblies are supported by [3] / 8 -inch (10 mm) or [1] / 2 -inch (13-mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the pipe support point to the connection at the supporting structure, and no single pipe exceeds the diameter limits set forth in item 2b or 2 inches (50 mm) where I p is greater than 1.0 and the total weight supported by any single trapeze is 100 pounds (445 N) or less; or 2. Piping is supported by rod hangers and provisions are made to avoid impact with other structural or nonstructural components or to protect the piping in the event of such impact; or pipes are supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, where each hanger in the pipe run is 12 inches (305 mm) or less in length from the pipe support point to the connection at the supporting structure, and the total weight supported by any single hanger is 50 pounds (220 N) or less. In addition, the following limitations on the size of piping shall be observed: a. In structures assigned to Seismic Design Category D, E or F where I p is greater than 1.0, the nominal pipe size shall be 1 inch (25 mm) or less. b. In structures assigned to Seismic Design Category D, E or F where I p = 1.0, the nominal pipe size shall be 3 inches (80 mm) or less. 3. Pneumatic tube systems supported with trapeze assemblies using [3] / 8 -inch (10 mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the tube support point to the connection at the supporting structure and the total weight supported by any single trapeze is 100 pounds (445 N) or less. 4. Pneumatic tube systems supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, and each hanger in the run is 12 inches (305 mm) or less in length from the tube support point to the connection at the supporting structure, and the total weight supported by any single rod is 50 pounds (220 N) or less. B) Flexible connections in piping required in Section 13.6.7.3 are not required where pipe is rigidly attached to the same floor or wall that provides vertical and lateral support for the equipment, or to a fixture. C) Flexible connections in piping are required at seismic separation joints and shall be detailed to accommodate the seis- mic relative displacements at connections.
CMC § 1617A.1.26 High relevance — show source text
1617A.1.26 ASCE 7, Section 13.6.7.3. Replace ASCE 7, Section 13.6.7.3 with the following:
13.6.7.3 Additional Provisions for Piping and Tubing Systems. A) Design for the seismic forces of Section 13.3 shall not be required for piping systems where flexible connections, expansion loops or other assemblies are provided to accommodate the relative displacement between component and piping, where the piping system is positively attached to the structure, and where any of the following conditions apply:
- Trapeze assemblies are supported by [3] / 8 -inch (10 mm) or [1] / 2 -inch (13 mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the pipe support point to the connection at the supporting structure, and no single pipe exceeds the diameter limits set forth in item 2b below or 2 inches (50 mm) where I p is greater than 1.0 and the total weight supported by any single trapeze is 100 pounds (445 N) or less; or 2. Piping is supported by rod hangers and provisions are made to avoid impact with other structural or nonstructural components or to protect the piping in the event of such impact; or pipes are supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, where each hanger in the pipe run is 12 inches (305 mm) or less in length from the pipe support point to the connection at the supporting structure, and the total weight supported by any single hanger is 50 pounds (220 N) or less. In addition, the following limitations on the size of piping shall be observed: a. In structures assigned to Seismic Design Category D, E or F where I p is greater than 1.0, the nominal pipe size shall be 1 inch (25 mm) or less. b. In structures assigned to Seismic Design Category D, E or F where I p = 1.0, the nominal pipe size shall be 3 inches (80 mm) or less. 3. Pneumatic tube systems supported with trapeze assemblies using [3] / 8 inch (10 mm) in diameter rod hangers not exceeding 12 inches (305 mm) in length from the tube support point to the connection at the supporting structure and the total weight supported by any single trapeze is 100 pounds (445 N) or less. 4. Pneumatic tube systems supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, and each hanger in the run is 12 inches (305 mm) or less in length from the tube support point to the connection at the supporting structure, and the total weight supported by any single rod is 50 pounds (220 N) or less. B) Flexible connections in piping required in Section 13.6.7.3 are not required where pipe is rigidly attached to the same floor or wall that provides vertical and lateral support for the equipment, or to a fixture. C) Flexible connections in piping are required at seismic separation joints and shall be detailed to accommodate the seis- mic relative displacements at connections.
CMC § 1210.4.3. High relevance — show source text
Fuel gas piping shall be protected in accordance with Section 1210.4.3.
312.10 Sleeves. Sleeves shall be provided to protect piping through concrete and masonry walls, and concrete floors. Exception: Sleeves shall not be required where openings are drilled or bored.
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GENERAL REGULATIONS
312.10.1 Building Loads. Piping through concrete or masonry walls shall not be subject to a load from building construction.
312.10.2 Exterior Walls. In exterior walls, annular space between sleeves and pipes shall be sealed and made watertight, as approved by the Authority Having Jurisdiction. A penetration through fire-resistive construction shall be in accordance with Section 312.7.
312.10.3 Firewalls. A pipe sleeve through a firewall shall have space around the pipe completely sealed with an approved fire-resistive material in accordance with other codes.
312.11 Structural Members. A structural member weakened or impaired by cutting, notching, or otherwise shall be reinforced, repaired, or replaced so as to be left in a safe structural condition in accordance with the requirements of the California Building Code or California Residential Code . 312.12 Rodentproofing. Strainer plates on drain inlets shall be designed and installed so that no opening exceeds [1] ⁄ 2 of an inch (12.7 mm) in the least dimension.
312.12.1 Meter Boxes. Meter boxes shall be con structed in such a manner as to restrict rodents or vermin from entering a building by following the service pipes from the box into the building. 312.12.2 Metal Collars. In or on buildings where openings have been made in walls, floors, or ceilings for the passage of pipes, such openings shall be closed and protected by the installation of approved metal collars securely fastened to the adjoining structure. 312.12.3 Tub Waste Openings. Tub waste openings in framed construction to crawl spaces at or below the first floor shall be protected by the installation of approved metal collars or metal screen securely fastened to the adjoining structure with no opening exceeding [1] ⁄ 2 of an inch (12.7 mm) in the least dimension.
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, fixtures, appliances, and appurtenances shall be supported in accordance with this code, the manufacturer’s installation instructions, and in accordance with the Authority Having Jurisdiction. Seismic restraints shall be in accordance with the building code. 313.2 Material. Hangers, supports, and anchors shall be of sufficient strength to support the weight of the pipe or tubing and its contents. Piping or tubing shall be isolated from incompatible materials. 313.3 Suspended Piping. Suspended piping shall be supported at intervals not to exceed those shown in Table 313.3. 313.4 Alignment. Piping shall be supported in such a manner as to maintain its alignment and prevent sagging. 313.5 Underground Installation. Piping in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 301.2.
CMC § 3109F.3 High relevance — show source text
_ 5. A guide or lateral restraint shall be provided just past the elbow where a pipe changes direction in order to minimize excessive axial stress (N). 6. Piping shall be routed to allow for movement due to thermal expansion and seismic displacement, without exceeding the allowable stresses in the supports, and anchor connections (see Section 3109F.3) (N/E). 7. Plastic piping shall not be used unless designated for oil service (N/E). 8. If a flanged connection exists within 20 pipe diameters from the end of any replaced section, the pipe shall be replaced up to and including the flange. 9. Pipelines shall be seamless, electric-resistance-welded or electric-fusion-welded (N). 10. Piping greater than 2 inches in diameter shall be butt-welded. Piping 2 inches and smaller shall be socket welded or threaded. 11. Pipeline connections directly over the water shall be welded (N). Flanged connections not over water shall have secondary containment (N). 12. Pipelines that do not have a valid and certified Static Liquid Pressure Test (SLPT) [9.4] shall be marked “OUT OF SERVICE.” Out- of-service piping and pipelines shall be purged, gas-freed and physically isolated from sources of oil. 13. If a pipeline is “out-of-service” for 3 or more years, it will require a valid and certified Static Liquid Pressure Test (SLPT) and API 570 inspection [9.4] prior to Division approval for re-use (E). 14. New piping and pipeline systems require a valid and certified Static Liquid Pressure Test (SLPT) [9.4] and Division approval, prior to operation.
3109F.3 Pipeline stress analysis (N/E). Pipeline stress analysis shall be performed for: 1. New piping and pipelines 2. Significant rerouting/relocation of existing piping 3. Any replacement of “not in-kind” piping 4. Any significant rearrangement or replacement of “not in-kind” anchors and/or supports 5. Significant seismic displacements calculated from the structural and/or geotechnical assessments
Pipeline stress analysis shall be performed in accordance with ASME B31.4 [9.3], considering all relevant loads and corresponding displacements determined from the structural analysis and/or geotechnical analysis described in Sections 3104F and 3106F, respec- tively. Seismic loading of above-grade pipelines may be analyzed in accordance with ASME B31.E [9.5] with seismic loads computed from Section 3104F.5.4.1.
For pipelines spanning between seismically isolated structures (Section 3104F.1.3) and/or varying geotechnical conditions, evalua- tion of the relative movement of pipelines and supports and varying seismic accelerations shall be considered, including phase differences.
Flexibility analysis for piping, considering supports, shall be performed in accordance with ASME B31.4 [9.3] by using the largest temperature differential imposed by normal operation, start-up, shutdown or abnormal conditions. Thermal loads shall be based upon maximum and minimum local temperatures; heat traced piping shall use the maximum attainable temperature of the heat tracing system.
Section 3106F.12 provides additional considerations for underwater seafloor pipelines.
31F-84 2025 CALIFORNIA BUILDING CODE
CMC § 16A-40 High relevance — show source text
16A-40 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
STRUCTURAL DESIGN
the duct system and associated components, the duct system is positively attached to the structure, and where one of the following apply: a. Trapeze assemblies with [3] / 8 -inch (10 mm) or [1] / 2 -inch (13 mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the duct support point to the connection at the supporting structure are used to support duct, and the total weight supported by any single trapeze is less than 10 lb/ft (146 N/m) and 100 pounds or less; or b. The duct is supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, and each hanger in the duct run is 12 inches (305 mm) or less in length from the duct support point to the connection at the supporting structure, and the total weight supported by any single rod is 50 pounds (220 N) or less. 2. Design for the seismic forces and relative displacements of Section 13.3 shall not be required where provisions are made to avoid impact with other ducts or mechanical components or to protect the ducts in the event of such impact, the distribution system is positively attached to the structure; and HVACR ducts have a cross-sectional area of less than 6 square feet (0.557 m [2] ) and weigh 20 lb/ft (292 N/m) or less.
Components that are installed in line with the duct system and have an operating weight greater than 75 pounds (334 N), such as fans, terminal units, heat exchangers and humidifiers, shall be supported and laterally braced independent of the duct system, and such braces shall meet the force requirements of Section 13.3.1. Components that are installed in line with the duct system, have an operating weight of 75 pounds (334 N) or less, such as small terminal units, dampers, louvers and diffusers, and are otherwise not independently braced shall be positively attached with mechanical fasteners to the rigid duct on both sides. Piping and conduit attached to in-line equipment shall be provided with adequate flexibility to accommodate the seismic relative displacements of Section 13.3.2.
1617A.1.26 ASCE 7, Section 13.6.7.3. Replace ASCE 7, Section 13.6.7.3 with the following:
13.6.7.3 Additional Provisions for Piping and Tubing Systems. A) Design for the seismic forces of Section 13.3 shall not be required for piping systems where flexible connections, expansion loops or other assemblies are provided to accommodate the relative displacement between component and piping, where the piping system is positively attached to the structure, and where any of the following conditions apply:
- Trapeze assemblies are supported by [3] / 8 -inch (10 mm) or [1] / 2 -inch (13 mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the pipe support point to the connection at the supporting structure, and no single pipe exceeds the diameter limits set forth in item 2b below or 2 inches (50 mm) where I p _is greater than 1.
CMC § 1310.3.4 High relevance — show source text
1310.3.4 Prohibited Locations. Gas piping inside any building shall not be installed in or through a clothes chute, chimney or gas vent, dumbwaiter, elevator shaft, or air duct, other than combustion air ducts. [NFPA 54:7.2.5]
Exception: Ducts used to provide ventilation air in accordance with Section 701.0 or to above-ceiling spaces in accordance with Section 1310.3.3.1.
1310.3.5 Hangers, Supports, and Anchors. Piping shall be supported with metal pipe hooks, metal pipe straps, metal bands, metal brackets, metal hangers, or building structural components, suitable for the size of piping, of adequate strength and quality, and located at intervals so as to prevent or damp out excessive vibration. Piping shall be anchored to prevent undue strains on connected appliances and equipment and shall not be supported by other piping. Pipe hangers and supports shall conform to the requirements of MSS SP-58. [NFPA 54:7.2.6.1]
1310.3.5.1 Spacing. Spacing of supports in gas piping installations shall not be greater than shown in Table 1310.3.5.1. Spacing of supports of CSST shall be in accordance with the CSST manufac turer’s instructions. [NFPA 54:7.2.6.2]
TABLE 1310.3.5.1
SUPPORT OF PIPING
[NFPA 54: TABLE 7.2.6.2]
STEEL PIPE,
NOMINAL SIZE
OF PIPE(inches)SPACING OF
SUPPORTS
(feet)NOMINAL SIZE
OF TUBING
SMOOTH WALL
(inches O.D.)SPACING OF
SUPPORTS
(feet)1⁄2 6 1⁄2 4
3⁄4 or 18 5⁄8 or3⁄4 6
11⁄4 or larger
(horizontal)10 7⁄8 or 1
(horizontal)8
11⁄4 or larger
(vertical)Every floor
level1 or larger
(vertical)Every floor
levelFor SI units: 1 inch = 25 mm, 1 foot = 304.8 mm
1310.3.5.2 Expansion and Contraction. Supports, hangers, and anchors shall be installed so as not to interfere with the free expansion and contraction of the piping between anchors. All parts of the supporting system shall be designed and installed so they are not disengaged by movement of the supported piping. [NFPA 54:7.2.6.3]
1310.3.5.3 Piping on Roofs. Gas piping installed on the roof surfaces shall be supported in accordance with Table 1310.3.5.1. Gas piping shall be elevated not less than 3½ inches (89 mm) above the roof surface. [NFPA 54:7.2.6.4.1, 7.2.6.4.2]
CMC § 1210.3.4 Medium relevance — show source text
Exception: Appliance or equipment shutoff valves required by this code shall be permitted to be installed in accessible spaces containing vented appliances. 1210.3.4 Prohibited Locations. Gas piping inside any building shall not be installed in or through a clothes chute, chimney or gas vent, dumbwaiter, elevator shaft, or air duct, other than combustion air ducts. [NFPA 54:7.2.5]
Exception: Ducts used to provide ventilation air in accordance with Section 506.0 or to above-ceiling spaces in accordance with Section 1210.3.3.1.
1210.3.5 Hangers, Supports, and Anchors. Piping shall be supported with metal pipe hooks, metal pipe straps, metal bands, metal brackets, metal hangers, or building structural components, suitable for the size of piping, of adequate strength and quality, and located at intervals so as to prevent or damp out excessive vibration. Piping shall be anchored to prevent undue strains on connected appliances and equipment and shall not be supported by other piping. Pipe hangers and supports shall conform to the requirements of MSS SP-58. [NFPA 54:7.2.6.1] 1210.3.5.1 Spacing. Spacing of supports in gas piping installations shall not be greater than shown in Table 1210.3.5.1. Spacing of supports of CSST shall be in accordance with the CSST manufacturer’s instructions. [NFPA 54:7.2.6.2]
TABLE 1210.3.5.1
SUPPORT OF PIPING
[NFPA 54: TABLE 7.2.6.2]
STEEL PIPE,
NOMINAL SIZE
OF PIPE
(inches)SPACING OF
SUPPORTS
(feet)NOMINAL SIZE
OF TUBING
SMOOTH WALL
(inches O.D.)SPACING OF
SUPPORTS
(feet)
1⁄26 1⁄2 4 3⁄4 or 1 8 5⁄8 or3⁄4 6
11⁄4 or larger
(horizontal)10 7⁄8 or 1
(horizontal)8
11⁄4 or larger
(vertical)Every floor
level1 or larger
(vertical)Every floor
levelFor SI units: 1 inch = 25 mm, 1 foot = 304.8 mm
CMC § 316.0 Medium relevance — show source text
open position and located within 30 feet (9144 mm) of the grade shall be tested for impact resistance in accordance with AMCA 540.
316.0 Protection of Piping, Tubing, Materials, and Structures.
316.1 General. Piping or tubing passing under or through walls shall be protected from breakage. Piping passing through or under cinders or other corrosive materials shall be protected from external corrosion in an approved manner. Approved provisions shall be made for expansion of hot water piping. Voids around piping or tubing passing through concrete floors on the ground shall be sealed.
316.2 Installation. Piping or tubing shall be installed so that the piping, tubing, or connections will not be subject to undue strains or stresses, and provisions shall be made for expansion, contraction, and structural settlement. No piping or tubing, unless designed and listed for such use, shall be directly embedded in concrete or masonry. No structural member shall be seriously weakened or impaired by cutting, notching, or otherwise as defined in the California Building Code or California Residential Code .
316.3 Corrosion, Erosion, and Mechanical Damage. Piping or tubing subject to corrosion, erosion, or mechanical damage shall be protected in an approved manner.
316.4 Protectively Coated Pipe. Protectively coated pipe or tubing shall be inspected and tested, and a visible void, damage, or imperfection to the pipe coating shall be repaired in an approved manner.
316.5 Fire-Resistant Construction. Piping, tubing, and duct system penetrations of fire-resistance-rated walls, parti
For SI units: 1 inch = 25.4 mm
2025 CALIFORNIA MECHANICAL CODE 59
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
GENERAL REGULATIONS
tions, floors, floor/ceiling assemblies, roof/ceiling assemblies, or shaft enclosures shall be protected in accordance with the requirements of the California Building Code or California Residential Code .
316.6 Steel Nail Plates. Plastic piping or tubing, copper or copper alloy piping or tubing, and ducts penetrating framing members to within 1 inch (25.4 mm) of the exposed framing shall be protected by steel nail plates not less than No. 18 gauge (0.0478 inches) (1.2141 mm) in thickness. The steel nail plate shall extend along the framing member not less than 1 [1] ⁄ 2 inches (38 mm) beyond the outside diameter of the pipe or tubing. Fuel gas piping shall be protected in accordance with Section 1310.4.3.
316.7 Sleeves. Sleeves shall be provided to protect piping through concrete and masonry walls and concrete floors.
Exception: Sleeves shall not be required where openings are drilled or bored.
316.7.1 Building Loads. Piping or tubing through concrete or masonry walls shall not be subject to a load from building construction.
316.7.2 Exterior Walls. In exterior walls, annular space between sleeves and pipes or tubing shall be sealed and made watertight, as approved by the Authority Having Jurisdiction. A penetration through fire-resistive construction shall be in accordance with Section 316.5.
CMC § 313.1 High relevance — show source text
313.1 General. . . . . . . . . . . . . . . . . . . . . . 59
313.2 Material. . . . . . . . . . . . . . . . . . . . . . 59
313.3 Suspended Piping . . . . . . . . . . . . . 59
313.4 Alignment . . . . . . . . . . . . . . . . . . . . 59
313.5 Underground Installation . . . . . . . . 59
313.6 Hanger Rod Sizes . . . . . . . . . . . . . 59
Table 313.6 Hanger Rod Sizes . . . . . . . . . . . . . 59
313.7 Gas Piping . . . . . . . . . . . . . . . . . . . 59
314.0 Balancing . . . . . . . . . . . . . . . . . . . . 59
314.1 General. . . . . . . . . . . . . . . . . . . . . . 59
315.0 Louvers in Hurricane Prone
Regions . . . . . . . . . . . . . . . . . . . . . 59
315.1 General. . . . . . . . . . . . . . . . . . . . . . 59
2025 CALIFORNIA MECHANICAL CODE
316.0 Protection of Piping, Tubing, Materials, and Structures . . . . . . . . 59
316.1 General. . . . . . . . . . . . . . . . . . . . . . 59
316.2 Installation . . . . . . . . . . . . . . . . . . . 59
316.3 Corrosion, Erosion, and Mechanical Damage. . . . . . . . . . . . 59
316.4 Protectively Coated Pipe . . . . . . . . 59
316.5 Fire-Resistant Construction . . . . . . 59
316.6 Steel Nail Plates . . . . . . . . . . . . . . . 60
316.7 Sleeves. . . . . . . . . . . . . . . . . . . . . . 60
316.8 Firewalls . . . . . . . . . . . . . . . . . . . . . 60
316.9 Structural Members . . . . . . . . . . . . 60
316.10 Rodentproofing . . . . . . . . . . . . . . . . 60
316.11 Metal Collars. . . . . . . . . . . . . . . . . . 60
317.0 Trenching, Excavation, and
Backfill . . . . . . . . . . . . . . . . . . . . . . 60
317.1 Trenches. . . . . . . . . . . . . . . . . . . . . 60
317.2 Tunneling and Driving. . . . . . . . . . . 60
317.3 Open Trenches. . . . . . . . . . . . . . . . 60
317.4 Excavations . . . . . . . . . . . . . . . . . . 60
CMC § 6.4 Medium relevance — show source text
- Installation and anchorage of ductwork designed to carry hazardous materials in structures assigned to Seismic Design Category C, D, E or F.
- Installation and anchorage of vibration isolation systems in structures assigned to Seismic Design Category C, D, E or F where the approved construction documents require a nominal clearance of [1] / 4 inch (6.4 mm) or less between the equipment support frame and restraint.
2025 CALIFORNIA BUILDING CODE 17-15
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
SPECIAL INSPECTIONS AND TESTS
- Installation of mechanical and electrical equipment, including duct work, piping systems and their structural supports, where automatic sprinkler systems are installed in structures assigned to Seismic Design Category C, D, E or F to verify one of the following: 6.1. Minimum clearances have been provided as required by Section 13.2.4 ASCE/SEI 7. 6.2. A nominal clearance of not less than 3 inches (76 mm) has been be provided between automatic sprinkler system drops and sprigs and: structural members not used collectively or independently to support the sprinklers; equipment attached to the building structure; and other systems’ piping.
Where flexible sprinkler hose fittings are used, special inspection of minimum clearances is not required.
1705.13.7 Storage racks. Steel storage racks and steel cantilevered storage racks that are 8 feet (2438 mm) in height or greater and assigned to Seismic Design Category D, E or F shall be provided with periodic special inspection as required by Table 1705.13.7.
TABLE 1705.13.7—REQUIRED INSPECTIONS OF STORAGE RACK SYSTEMS Col2 Col3 Col4 Col5 TYPE CONTINUOUS
INSPECTIONPERIODIC
INSPECTIONREFERENCED
STANDARDIBC REFERENCE 1. Materials used, to verify compliance with one or more of the
material test reports in accordance with the approved
construction documents.— X — — 2. Fabricated storage rack elements. — X — Section 1704.2.5 3. Storage rack anchorage installation. — X ANSI/MH16.1
Section 7.3.2— 4. Completed storage rack system, to indicate compliance with
the approved construction documents.— X — — 1705.13.8 Seismic isolation systems. Periodic special inspection shall be provided for seismic isolation systems in seismically isolated structures assigned to Seismic Design Category B, C, D, E or F during the fabrication and installation of isolator units and energy dissipation devices.
1705.13.9 Cold-formed steel special bolted moment frames. Periodic special inspection shall be provided for the installation of cold-formed steel special bolted moment frames in the seismic force-resisting systems of structures assigned to Seismic Design Category D, E or F.
1705.14 Testing for seismic resistance. Testing for seismic resistance shall be required as specified in Sections 1705.14.1 through 1705.14.4, unless exempted from special inspections by the exceptions of Section 1704.2.
Frequently asked questions
Do I have to use the exact hanger rod sizes in Table 313.6?
Yes — § 313.6 requires hanger rod sizes be not smaller than those in Table 313.6. Use the table values as your minimum; larger rods are acceptable if required by load/stress analysis.
Where do I find the allowed support spacing for a given pipe size?
The CMC requires you to use Table 313.3 for suspended piping spacing under § 313.3. The numeric table values are in the Code’s Table 313.3 — consult the printed Code, your project documents, or the AHJ.
Does the CMC spell out seismic bracing details for piping?
No — the CMC states seismic restraints shall be in accordance with the building code (§ 313.1). See the California Building Code (ASCE 7 provisions and California amendments) for seismic design rules and the specific exceptions that may apply.
What if my pipe run exceeds the weight limits in the Building Code exception?
If hanger/trapeze weights or sizes exceed the exception thresholds in the Building Code amendment, the piping must be designed for seismic forces per the Building Code (that generally requires seismic bracing/anchorage to the structural system). Consult the Building Code text and a structural or mechanical engineer.
Are there special rules for gas piping supports?
Yes — gas piping support spacing and methods are given in the Code’s gas‑piping sections and their tables (see Table 1310.3.5.1 / Table 1210.3.5.1 as referenced by the CMC). Follow those gas‑specific tables and requirements in addition to general CMC support rules.
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