CMC · California Mechanical Code
What material and standard requirements apply to process pipe, tubing and fittings?
For homeowners: any process piping in a building must be made from materials and fittings that meet ASME B31.3, be installed exactly as the maker directs, and be rated and chemically compatible with the temperatures, pressures and liquids in the system — that’s the requirement in § 1406.1 of the California Mechanical Code.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
Process piping materials and fittings used in mechanical process systems must meet the ASME B31.3 standard, be installed in accordance with the manufacturer’s installation instructions, and be rated for the operating temperatures and pressures and compatible with the liquid being conveyed. This is the plain‑English rule of § 1406.1 (the chapter heading appears at § 1406.0) of the California Mechanical Code.
The single most important requirement: use piping, tubing and fittings that comply with ASME B31.3, follow the manufacturer’s installation instructions, and verify the material’s temperature/pressure ratings and chemical compatibility.
Requirements in detail
Key terms (first mention bolded)
- process pipe, tubing, and fittings — the components covered by the rule in § 1406.1.
- ASME B31.3 — the mandatory referenced standard for process piping in § 1406.1.
What you must check before specifying or installing piping
- Confirm the product is manufactured to or listed to ASME B31.3 as required by § 1406.1.
- Verify the material’s published pressure rating and temperature rating meet or exceed the system’s maximum operating pressure and temperature (the Code requires materials be “rated for the operating temperatures and pressures of the system”). § 1406.1.
- Confirm chemical compatibility between the material and the fluid being transported (the Code requires materials “compatible with the type of liquid”). § 1406.1.
- Install exactly per the manufacturer’s installation instructions; the Code requires installation in accordance with those instructions. § 1406.1.
Decision‑relevant checklist (table)
| Decision item | What to look for on the product / spec | Code Reference |
|---|---|---|
| Required standard | Product or system documented to comply with ASME B31.3 | § 1406.1 |
| Installation method | Manufacturer’s written installation instructions; use those procedures | § 1406.1 |
| Pressure rating | Published maximum working pressure ≥ design/operating pressure | § 1406.1 |
| Temperature rating | Published maximum/minimum temperature range covers system conditions | § 1406.1 |
| Chemical compatibility | Manufacturer or standard chemistry tables show compatibility with the liquid | § 1406.1 |
Notes on evidence/documentation
- Maintain manufacturer data sheets, material certifications, and installation instructions on the job so the Authority Having Jurisdiction (AHJ) can verify compliance (the Code ties installation to manufacturer instructions and ASME B31.3). § 1406.1.
Exceptions & special cases
- Section § 1406.1 itself does not list exceptions; it establishes the baseline requirements only (product compliance with ASME B31.3, manufacturer installation instructions, ratings, and compatibility). If your installation involves hazardous process piping, separate additional requirements apply under § 1406.2 (visibility, identification, spill containment) — see Related Provisions below.
- The CMC places further design/installation and inspection duties elsewhere (for example, inspection/testing requirements appear in other sections) — those are related but not exceptions to § 1406.1.
Common mistakes
- Relying on a material’s common use rather than confirming it explicitly complies with ASME B31.3. The Code requires ASME B31.3 compliance for process piping. § 1406.1.
- Installing a pipe/tubing/fitting without verifying the manufacturer’s temperature/pressure ratings — the Code requires materials be rated for the operating temperatures and pressures of the system. § 1406.1.
- Ignoring chemical compatibility between fluid and piping material (corrosion, swelling, embrittlement). The Code requires compatibility with the type of liquid. § 1406.1.
- Departing from the manufacturer’s installation instructions (e.g., using unapproved joining methods or incorrect torque/temperature limits). The Code mandates installation per those instructions. § 1406.1.
Worked example — concrete scenario
Scenario: A small process branch carries a solvent at an operating temperature of 180°F and a maximum operating pressure of 75 psi.
Steps to demonstrate compliance with § 1406.1:
- Specify piping and fittings that the manufacturer documents as produced/tested to ASME B31.3. Evidence: product datasheet or marking showing compliance. § 1406.1.
- From the datasheet, confirm the material’s maximum continuous temperature rating is ≥ 180°F and its maximum working pressure rating is ≥ 75 psi (Code requires the material be rated for the operating temperatures and pressures). If ratings are lower, choose a different material/product. § 1406.1.
- Confirm chemical compatibility between the solvent and the chosen material (manufacturer compatibility tables or chemical resistance data). If incompatible, select a different material or lined piping. § 1406.1.
- Install per the manufacturer’s installation instructions (joining method, supports, allowable bending radius, etc.). Retain the instructions on site for inspection. § 1406.1.
Note: § 1406.1 prescribes the requirements but does not prescribe the specific numeric material limits — you must use manufacturer ratings and ASME B31.3 guidance to make the selection.
Related provisions
- § 1406.2 — Hazardous Process Piping (HPP): additional requirements for HPP visibility, identification, and spill containment.
- § 1405.2 — Required Inspections: includes rough and final piping inspections and pressure testing (useful to ensure the installed piping meets the material/installation requirements at inspection).
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 1.1.2 High relevance — show source text
1.1.2 This Standards applies to
(a) SDR 9 CTS PEX tubing complying with ASTM F876 and pressure-rated in accordance with PPI TR-3; and (b) PEX fitting systems complying with (i) ASTM F877, for mechanical compression fittings and metal or plastic insert fittings with stainless steel press sleeves; (ii) ASTM F1807 or ASTM F2159, for metal or plastic insert fittings with copper crimp rings; (iii) ASTM F1960, for cold expansion fittings with PEX reinforced rings; or (iv) ASTM F2080, for cold expansion fittings with metal compression sleeves. 1.2 Terminology
In this Standard,
(a) “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy to comply with the Standard; (b) “should” is used to express a recommendation, but not a requirement; (c) “may” is used to express an option or something permissible within the scope of the Standard; and (d) “can” is used to express a possibility or a capability. Notes accompanying sections of the Standard do not specify requirements or alternative requirements; their purpose is to separate explanatory or informa
tive material from the text. Notes to tables and figures are considered part of the table or figure and can be written as requirements.
1.3 Units of Measurement
SI units are the primary units of record in global commerce. In this Standard, the inch/pound units are shown in parentheses. The values stated in each measurement system are equivalent in application, but each unit system is to be used independently. All references to gallons are to U.S. gallons.
2 Reference Publications
This Standard refers to the following publications, and where such reference is made, it shall be to the current edition of those publications, including all amendments published thereto.
ASTM International
ASTM F876 Standard Specification for Crosslinked Polyethylene (PEX) Tubing
ASTM F877 Standard Specification for Crosslinked Polyethylene (PEX) Hot- and Cold-Water Distribution Systems
ASTM F1807 Standard Specification for Metal Insert Fittings Utilizing a Copper Crimp Ring, or Alternate Stainless Steel Clamps, for SDR9 Crosslinked Polyethylene (PEX) Tubing and SDR9 Polyethylene of Raised Temperature (PE-RT) Tubing
ASTM F1960 Standard Specification for Cold Expansion Fittings with PEX Reinforcing Rings for Use with Cross-linked Polyethylene (PEX) Polyethylene of Raised Temperature (PE-RT) Tubing
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ASTM F2080 Standard Specification for ColdExpansion Fittings with Metal Compression-Sleeves for CrossLinked Polyethylene (PEX) Pipe and SDR9 Polyethylene of Raised Temperature (PE-RT) Pipe
ASTM F2159 Standard Specification for Plastic Insert Fittings Utilizing a Copper Crimp Ring, or Alternate Stainless Steel Clamps for SDR9 Cross-linked Polyethylene (PEX) Tubing and SDR9 Polyethylene of Raised Temperature (PE-RT) Tubing
ASTM F2657 Standard Test Method for Out door Weathering Exposure of Crosslinked Polyethylene (PEX) Tubing
AWWA (American Water Works Association)
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
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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 § 20.1. High relevance — show source text
(6) Soldered joints between copper or copper alloy pipe or tubing and fittings shall be made in accordance with ASTM B828. Pipe or tubing shall be cut square and reamed to the full inside diameter including the removal of burrs on the outside of the pipe or tubing. Surfaces to be joined shall be cleaned bright by manual or mechanical means. Flux shall be applied to pipe or tubing and fittings and shall be in accordance with ASTM B813, and shall become noncorrosive and nontoxic after soldering. Insert pipe or tubing into the base of the fitting and remove excess flux. Pipe or tubing and fitting shall be supported to ensure a uniform capillary space around the joint. Solder in accordance with ASTM B32 shall be applied to the joint surfaces until capillary action draws the molten solder into the cup. Joint surfaces shall not be disturbed until cool, and any remaining flux residue shall be cleaned.
(7) Threaded joints for copper or copper alloy pipe shall be made with pipe threads in accordance with ASME B1.20.1. Thread sealant tape or compound shall be applied only on male threads, and such material shall be of approved types, insoluble in water, and nontoxic.
1211.6 Cross-Linked Polyethylene (PEX) Pipe. Joints between cross-linked polyethylene (PEX) pipe and fittings shall be installed with fittings for PEX tubing that comply with the applicable standards referenced in Table 1210.1. PEX tubing labeled in accordance with ASTM F876 or ASTM F3253 shall be marked with the applicable standard designation for the fittings specified for use with the tubing. Mechanical joints shall be installed in accordance with the manufacturer’s installation instructions.
1211.7 Cross-Linked Polyethylene/Aluminum/Cross- Linked Polyethylene (PEX-AL-PEX) Pipe. Joints between cross-linked polyethylene/aluminum/cross-linked polyethylene (PEX-AL-PEX) pipe and fittings shall be installed in accordance with one of the following methods:
(1) Mechanical joints between PEX-AL-PEX pipe and fittings shall include mechanical and compression type fittings and insert fittings with a crimping ring. Insert fittings utilizing a crimping ring shall be in accordance with ASTM F1974 or ASTM F2434. Crimp joints for crimp insert fittings shall be joined to PEX-AL-PEX pipe by the compression of a crimp ring around the outer circumference of the pipe, forcing the pipe material into annular spaces formed by ribs on the fitting.
(2) Compression joints shall include compression insert fittings and shall be joined to PEX-AL-PEX pipe through the compression of a split ring or compression nut around the outer circumference of the pipe, forcing the pipe material into the annular space formed by the ribs on the fitting. Note: [HCD 1 & HCD 2] PEX-AL-PEX is not adopted in the California Plumbing Code for use in potable water sup- ply and distribution systems.
1211.8 Ductile Iron Pipe. Joints between ductile iron pipe and fittings shall be installed in accordance with one of the following methods:
CMC § 5.5.7.5 High relevance — show source text
(8) Special fittings such as couplings, proprietarytype joints, saddle tees, gland-type compression fittings, and flared, flareless, or compressiontype tubing fittings shall be as follows: (a) Used within the fitting manufacturer’s pressure-temperature recommendations. (b) Used within the service conditions anticipated with respect to vibration, fatigue, thermal expansion, or contraction. (c) Acceptable to the Authority Having Jurisdiction.
(9) When pipe fittings are drilled and tapped in the field, the operation shall be in accordance with the following: (a) The operation shall be performed on systems having operating pressures of 5 psi (34 kPa) or less. (b) The operation shall be performed by the gas supplier or their designated representative.
(c) The drilling and tapping operation shall be performed in accordance with written procedures prepared by the gas supplier. (d) The fittings shall be located outdoors. (e) The tapped fitting assembly shall be inspected and proven to be free of leaks.
[NFPA 54:5.5.7.5] 1308.4.8 Plastic Piping Joints and Fittings. Plastic pipe, tubing, and fittings shall be joined in accordance with the manufacturers’ instructions. Section 1308.4.8.1 through Section 1308.4.8.4 shall be observed when making such joints. [NFPA 54:5.5.8] 1308.4.8.1 Joint Design. The joint shall be designed and installed so that the longitudinal pullout resistance of the joint will be at least equal to the tensile strength of the plastic piping material. [NFPA 54:5.5.8(1)] 1308.4.8.2 Heat Fusion Joint. Heat fusion joints shall be made in accordance with qualified procedures that have been established and proven by test to produce gastight joints at least as strong as the pipe or tubing being joined. Joints shall be made with the joining method recommended by the pipe manufacturer. Polyethylene heat fusion fittings shall be marked “ASTM D2513.” Polyamide heat fusion fittings shall be marked "ASTM F2945." [NFPA 54:5.5.8(2)]
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and temperature conditions and shall be selected giving consideration to joint tightness and mechanical strength under the service conditions. The joint shall be able to sustain the maximum end force due to the internal pressure and any additional forces due to temperature expansion or contraction, vibration, fatigue, or the weight of the pipe and its contents. [NFPA 54:5.5.7] 1308.4.7.1 Pipe Joints. Schedule 40 and heavier pipe joints shall be threaded, flanged, brazed, welded, or assembled with press-connect fittings listed to CSA/ANSI LC 4/CSA 6.32.
(1) Where nonferrous pipe is brazed, the brazing materials shall have a melting point in excess of 1000°F (538°C).
(2) Brazing alloys shall not contain more than 0.05 percent phosphorus. {NFPA 54:5.5.7.1} 1308.4.7.2 Copper Tubing Joints. Copper tubing joints shall be assembled with approved gas tubing fittings, shall be brazed with a material having a melting point in excess of 1000°F (538°C), or shall be assembled with press-connect fittings listed to CSA/ANSI LC 4/CSA 6.32.
CMC § 358-2 High relevance — show source text
11, NSF/ANSI 358-2|ASTM F2165, ASTM F2389,
CSA B137.11, NSF/ANSI 358-2| |Polyvinyl Chloride (PVC)|ASTM D1785, ASTM D2241,
CSA B137.3|ASTM D2464, ASTM D2466,
ASTM D2467, ASTM F1970,
CSA B137.2, CSA B137.3| |Polyethylene of Raised Temperature
(PE-RT)|ASTM F2165, ASTM F2623,
ASTM F2769, CSA B137.18|ASSE 1061, ASTM F1807, ASTM F2159,
ASTM F2165, ASTM F2735, ASTM F2769,
ASTM D3261, ASTM F3347, ASTM F3348,
ASTM F1055, CSA B137.18| |Cross-Linked Polyethylene/
Aluminum/Cross-Linked Polyethylene
(PEX-AL-PEX)|ASTM F1281, ASTM F2165,
CSA B137.10|ASTM F1281, ASTM F1974, ASTM F2165,
ASTM F2434, CSA B137.10| |Polyethylene/Aluminum/Polyethylene
(PE-AL-PE)|ASTM F1282, ASTM F2165,
CSA B137.9|ASTM F1282, ASTM F1974,
ASTM F2165, CSA B137.9| |Chlorinated Polyvinyl Chloride/Alu-
minum/ Chlorinated Polyvinyl Chloride
(CPVC/AL/CPVC)|ASTM F2855|ASTM D2846|Notes: 1 Ductile and gray iron. 2 Only type K, L, or M tubing allowed to be installed.
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HYDRONICS
the pressure rating of the pipe provided that the molded fittings shall be fabricated so that the wall thickness of the material is maintained at the threads. Thread sealant compound that is compatible with the pipe and fitting, insoluble in water, and nontoxic shall be applied to male threads. Caution shall be used during assembly to prevent over tightening of the CPVC components once the thread sealant has been applied. Female CPVC threaded fittings shall be used with plastic male threads only. 1211.4 CPVC/AL/CPVC Plastic Pipe and Joints. Joints between chlorinated polyvinyl chloride/aluminum/ chlorinated polyvinyl chloride (CPVC/AL/CPVC) pipe and fittings shall be installed in accordance with one of the following methods:
(1) Mechanical joints shall include flanged, grooved, and push-fit fittings.
(2) Solvent cement joints for CPVC/AL/CPVC pipe and fittings shall be clean from dirt and moisture. Solvent cements in accordance with ASTM F493, requiring the use of a primer shall be orange in color. The primer shall be colored and be in accordance with ASTM F656.
CMC § 20.1. High relevance — show source text
(2) Solvent cement joints for PVC pipe and fittings shall be clean from dirt and moisture. Pipe shall be cut square and pipe shall be deburred. Where surfaces to be joined are cleaned and free of dirt, moisture, oil, and other foreign material, apply primer purple in color in accordance with ASTM F656. Primer shall be applied until the surface of the pipe and fitting is softened. Solvent cements in accordance with ASTM D2564 shall be applied to all joint surfaces. Joints shall be made while both the inside socket surface and outside surface of pipe are wet with solvent cement. Hold joint in place and undisturbed for 1 minute after assembly.
(3) Threads shall comply with ASME B1.20.1. A minimum of Schedule 80 shall be permitted to be threaded; however, the pressure rating shall be reduced by 50 percent. The use of molded fittings shall not result in a 50 per
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(1) Butt-fusion joints shall be installed in accordance with ASTM F2620 and shall be made by heating the squared ends of two pipes, pipe and fitting, or two fittings by holding ends against a heated element. The heated element shall be removed where the proper melt is obtained, and joined ends shall be placed together with applied force. (2) Electro-fusion joints shall be heated internally by a conductor at the interface of the joint. Align and restrain fitting to pipe to prevent movement and apply electric current to the fitting. Turn off the current when the proper time has elapse to heat the joint. The joint shall fuse together and remain undisturbed until cool. (3) Socket-fusion joints shall be installed in accordance ASTM F2620 and shall be made by simultaneously heating the outside surface of a pipe end and the inside of a fitting socket. Where the proper melt is obtained, the pipe and fitting shall be joined by inserting one into the other with applied force. The joint shall fuse together and remain undisturbed until cool.
(4) Mechanical joints between PE pipe or tubing and fittings shall include insert and mechanical compression fittings that provide a pressure seal resistance to pullout. Joints for insert fittings shall be made by cutting the pipe square, using a cutter designed for plastic piping, and removal of sharp edges. Two stainless steel clamps shall be placed over the end of the pipe. Fittings shall be checked for proper size based on the diameter of the pipe. The end of pipe shall be placed over the barbed insert fitting, making contact with the fitting shoulder. Clamps shall be positioned equal to 180 degrees (3.14 rad) apart and shall be tightened to provide a leak tight joint. Compression type couplings and fittings shall be permitted for use in joining PE piping and tubing. Stiffeners that extend beyond the clamp or nut shall be prohibited. Bends shall be not less than 30 pipe diameters, or the coil radius where bending with the coil. Bends shall not be permitted closer than 10 pipe diameters of a fitting or valve. Mechanical joints shall be designed for their intended use. 1211.10 Polyethylene/Aluminum/Polyethylene (PE- AL-PE). Joints between polyethylene/aluminum/polyethylene (PE-AL-PE) pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints for PE-AL-PE pipe or tubing and fittings shall be either of the metal insert fittings with a split ring and compression nut or metal insert fittings with copper crimp rings.
CMC § 4.1 High relevance — show source text
This Standard refers to the following publications, and where such reference is made, it shall be to the current edition of those publications, including all amendments published thereto.
ASTM International
ASTM F876 Standard Specification for Crosslinked Polyethylene (PEX) Tubing
ASTM F877 Standard Specification for Crosslinked Polyethylene (PEX) Hot- and Cold-Water Distribution Systems
ASTM F1807 Standard Specification for Metal Insert Fittings Utilizing a Copper Crimp Ring, or Alternate Stainless Steel Clamps, for SDR9 Crosslinked Polyethylene (PEX) Tubing and SDR9 Polyethylene of Raised Temperature (PE-RT) Tubing
ASTM F1960 Standard Specification for Cold Expansion Fittings with PEX Reinforcing Rings for Use with Cross-linked Polyethylene (PEX) Polyethylene of Raised Temperature (PE-RT) Tubing
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ASTM F2080 Standard Specification for ColdExpansion Fittings with Metal Compression-Sleeves for CrossLinked Polyethylene (PEX) Pipe and SDR9 Polyethylene of Raised Temperature (PE-RT) Pipe
ASTM F2159 Standard Specification for Plastic Insert Fittings Utilizing a Copper Crimp Ring, or Alternate Stainless Steel Clamps for SDR9 Cross-linked Polyethylene (PEX) Tubing and SDR9 Polyethylene of Raised Temperature (PE-RT) Tubing
ASTM F2657 Standard Test Method for Out door Weathering Exposure of Crosslinked Polyethylene (PEX) Tubing
AWWA (American Water Works Association)
AWWA C904 Cross-Linked Polyethylene (PEX) Pressure Tubing, ½ In. (13 mm) Through 3 In. (76 mm), for Water Service
IAPMO (International Association of Plumb- ing and Mechanical Officials)
IAPMO/ANSI
UPC-1 Uniform Plumbing Code
PPI (Plastics Pipe Institute)
PPI TR-3 Policies and Procedures for
Developing Hydrostatic Design Basis (HDB), Hydrostatic Design Stresses (HDS), Pressure Design Basis (PDB), Strength Design Basis (SDB), Minimum Required Strength (MRS) Ratings, and Categorized Required Strength (CRS) for Thermoplastic Piping Materials or Pipe
3 Abbreviations
The following abbreviations apply in this Standard:
CTS — copper tube size
HDPE — high density polyethylene
IC — insulation contact
NTS — nominal tubing size
PEX — crosslinked polyethylene
SDR — standard dimension ratio
UV — ultraviolet light
4 General
4.1 Tubing
4.1.1 PEX tubing can be
(a) pigmented throughout (i.e., with color); (b) non-pigmented (e.g., translucent or natural); or (c) coated with a pigmented layer. 4.1.2 PEX tubing is typically available in NTS-1/4 to NTS-3.
4.1.3 Before installation, the installer shall review the tubing markings and verify that
CMC § 3.14 High relevance — show source text
Where the proper melt is obtained, the pipe and fitting shall be joined by inserting one into the other with applied force. The joint shall fuse together and remain undisturbed until cool.
(4) Mechanical joints between PE pipe or tubing and fittings shall include insert and mechanical compression fittings that provide a pressure seal resistance to pullout. Joints for insert fittings shall be made by cutting the pipe square, using a cutter designed for plastic piping, and removal of sharp edges. Two stainless steel clamps shall be placed over the end of the pipe. Fittings shall be checked for proper size based on the diameter of the pipe. The end of pipe shall be placed over the barbed insert fitting, making contact with the fitting shoulder. Clamps shall be positioned equal to 180 degrees (3.14 rad) apart and shall be tightened to provide a leak tight joint. Compression type couplings and fittings shall be permitted for use in joining PE piping and tubing. Stiffeners that extend beyond the clamp or nut shall be prohibited. Bends shall be not less than 30 pipe diameters, or the coil radius where bending with the coil. Bends shall not be permitted closer than 10 pipe diameters of a fitting or valve. Mechanical joints shall be designed for their intended use. 1211.10 Polyethylene/Aluminum/Polyethylene (PE- AL-PE). Joints between polyethylene/aluminum/polyethylene (PE-AL-PE) pipe and fittings shall be installed in accordance with one of the following methods: (1) Mechanical joints for PE-AL-PE pipe or tubing and fittings shall be either of the metal insert fittings with a split ring and compression nut or metal insert fittings with copper crimp rings. Metal insert fittings shall comply with ASTM F1974. Crimp insert fittings shall be joined to the pipe by placing the copper crimp ring around the outer circumference of the pipe, forcing the pipe material into the space formed by the ribs on the fitting until the pipe contacts the shoulder of the fitting. The crimp ring shall then be positioned on the pipe so the edge of the crimp ring is [1] / 8 of an inch (3.2 mm) to [1] / 4 of an inch (6.4 mm) from the end of the pipe. The jaws of the crimping tool shall be centered over the crimp ring and tool perpendicular to the barb. The jaws shall be closed around the crimp ring and shall not be crimped more than once. (2) Compression joints for PE-AL-PE pipe or tubing and fittings shall be joined through the compression of a split ring, by a compression nut around the circumference of
264 2025 CALIFORNIA MECHANICAL CODE
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HYDRONICS
shall be a soldered, brazed, flared, or pressed joint and the connection between the threaded pipe and the fitting shall be made with a standard pipe size threaded joint.
1211.16.2 Plastic Pipe to Other Materials. Where connecting plastic pipe to other types of plastic or other types of piping material; approved listed adapter or transition fittings and listed for the specific transition intended shall be used. Except as provided in the plumbing code, PVC pipe and fittings shall not be solvent welded to any other unlike material.
1212.0 Valves.
CMC § 1211.4 High relevance — show source text
ASTM F2165, CSA B137.9| |Chlorinated Polyvinyl Chloride/Alu-
minum/ Chlorinated Polyvinyl Chloride
(CPVC/AL/CPVC)|ASTM F2855|ASTM D2846|Notes: 1 Ductile and gray iron. 2 Only type K, L, or M tubing allowed to be installed.
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HYDRONICS
the pressure rating of the pipe provided that the molded fittings shall be fabricated so that the wall thickness of the material is maintained at the threads. Thread sealant compound that is compatible with the pipe and fitting, insoluble in water, and nontoxic shall be applied to male threads. Caution shall be used during assembly to prevent over tightening of the CPVC components once the thread sealant has been applied. Female CPVC threaded fittings shall be used with plastic male threads only. 1211.4 CPVC/AL/CPVC Plastic Pipe and Joints. Joints between chlorinated polyvinyl chloride/aluminum/ chlorinated polyvinyl chloride (CPVC/AL/CPVC) pipe and fittings shall be installed in accordance with one of the following methods:
(1) Mechanical joints shall include flanged, grooved, and push-fit fittings.
(2) Solvent cement joints for CPVC/AL/CPVC pipe and fittings shall be clean from dirt and moisture. Solvent cements in accordance with ASTM F493, requiring the use of a primer shall be orange in color. The primer shall be colored and be in accordance with ASTM F656.
Listed solvent cement in accordance with ASTM F493 that does not require the use of primers, yellow in color, shall be permitted for pipe and fittings manufactured in accordance with ASTM D2846, [1] ⁄ 2 of an inch (15 mm) through 2 inches (50 mm) in diameter, [1] ⁄ 2 of an inch (15 mm) through 3 inches (80 mm) in diameter. Apply primer where required inside the fitting and to the depth of the fitting on pipe. Apply liberal coat of cement to the outside surface of pipe to depth of fitting and inside of fitting. Place pipe inside fitting to forcefully bottom the pipe in the socket and hold together until joint is set. 1211.5 Copper or Copper Alloy Pipe and Tubing. Joints between copper or copper alloy pipe or tubing and fittings shall be installed in accordance with one of the following methods:
(1) Brazed joints between copper or copper alloy pipe or tubing and fittings shall be made with brazing alloys having a liquid temperature above 1000°F (538°C). The joint surfaces to be brazed shall be cleaned bright by either manual or mechanical means. Tubing shall be cut square and reamed to full inside diameter. Brazing flux shall be applied to the joint surfaces where required by manufacturer’s recommendation. Brazing filler metal in accordance with AWS A5.8 shall be applied at the point where the pipe or tubing enters the socket of the fitting.
CMC § 31-2022 High relevance — show source text
2025 CALIFORNIA PLUMBING CODE 453
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
454 2025 CALIFORNIA PLUMBING CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
"The information contained in this appendix is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this appendix may contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the standard."
The following IAPMO Installation Standard is included here for the convenience of the users of the Uniform Plumbing Code. It is not considered as a part of the Uniform Plumbing Code unless formally adopted as such. This Installation Standard is an independent, stand-alone document published by the International Association of Plumbing and Mechanical Officials and is printed herein by the expressed written permission of IAPMO.
INSTALLATION STANDARD FOR PEX TUBING SYSTEMS
FOR HOT- AND COLD-WATER DISTRIBUTION
IAPMO IS 31-2022
The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.
1 Scope
1.1 General
1.1.1 This Standard specifies requirements for the installation of SDR 9 CTS crosslinked polyethylene (PEX) tubing and fittings, including cold-expansion, crimp, press, and mechanical compression fittings, intended for hot- and cold-water distribution systems within buildings.
1.1.2 This Standards applies to
(a) SDR 9 CTS PEX tubing complying with ASTM F876 and pressure-rated in accordance with PPI TR-3; and (b) PEX fitting systems complying with (i) ASTM F877, for mechanical compression fittings and metal or plastic insert fittings with stainless steel press sleeves; (ii) ASTM F1807 or ASTM F2159, for metal or plastic insert fittings with copper crimp rings; (iii) ASTM F1960, for cold expansion fittings with PEX reinforced rings; or (iv) ASTM F2080, for cold expansion fittings with metal compression sleeves. 1.2 Terminology
In this Standard,
(a) “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy to comply with the Standard; (b) “should” is used to express a recommendation, but not a requirement; (c) “may” is used to express an option or something permissible within the scope of the Standard; and (d) “can” is used to express a possibility or a capability. Notes accompanying sections of the Standard do not specify requirements or alternative requirements; their purpose is to separate explanatory or informa
tive material from the text. Notes to tables and figures are considered part of the table or figure and can be written as requirements.
1.3 Units of Measurement
SI units are the primary units of record in global commerce. In this Standard, the inch/pound units are shown in parentheses. The values stated in each measurement system are equivalent in application, but each unit system is to be used independently. All references to gallons are to U.S. gallons.
2 Reference Publications
CMC § 4.1 High relevance — show source text
2 Reference Publications
This Standard refers to the following publications, and where such reference is made, it shall be to the current edition of those publications, including all amendments published thereto.
ASTM International
ASTM D3261
Standard Specification for Butt Heat Fusion Polyethylene (PE) Plastic Fittings for Polyethylene (PE) Plastic Pipe and Tubing
ASTM F714
Standard Specification for Polyethylene (PE) Plastic Pipe (DR-PR) Based on Outside Diameter
ASTM F894
Standard Specification for Polyethylene (PE) Large Diameter Profile Wall Sewer and Drain Pipe
ASTM F1055
Standard Specification for Electrofusion Type Polyethylene Fittings for Outside Diameter Controlled Polyethylene and Crosslinked Polyethylene (PEX) Pipe and Tubing
ASTM F2620
Standard Practice for Heat Fusion Joining of Polyethylene Pipe and Fittings
3 Abbreviations
The following abbreviations apply in this Standard:
PE — Polyethylene
HDPE — High Density Polyethylene
4 General
4.1 Product Requirements
Polyethylene (PE) sewer pipe or tubing and fitting joining methods shall be installed in accordance
2025 CALIFORNIA PLUMBING CODE 451
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
IS 26
with the manufacturer’s installation instructions and comply with ASTM F714, ASTM F894 the applicable nationally recognized standard.
4.2 HDPE Materials
HDPE Extra High Molecular Weight 3408 SDR 17 Pipe Socket-Type PE Fittings for Outside Diameter Controlled.
Note: The HDPE 3408 SDR 17 pipe used in this process was selected because of its ability to retain its circular shape even when bent on a 1.2 m (4 ft) radius during and after installation. 4.3 Protection of Pipe
Pipe shall be stored in a way to protect it from mechanical damage (slitting, puncturing, etc.). It shall be stored under cover to keep it clean and avoid long term exposure to sunlight. Exposure to sunlight during normal construction periods is acceptable. 4.4 Joining Methods
PE joints shall be made in accordance with the manufacturer’s installation instructions. PE pipe shall be joined to other pipe materials by an approved listed adapter or transition fittings listed for the specific transition intended.
4.4.1 Butt-Fusion Joints [2024 UPC 705.5.1.1]
Butt-fusion joints for PE pipe shall be installed in accordance with ASTM F2620 and shall be made by heating the prepared ends of two pipes, pipe and fitting, or two fittings by holding ends against a heated element. The heated element shall be removed when the required melt or times are obtained, and heated ends shall be placed together with applied force. Do not disturb the joint until cooled to ambient temper ature.
4.4.2 Electro-Fusion Joints [2024 UPC 705.5.1.2]
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
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PROCESS PIPING
areas not classified as Group H Occupancies, except as permitted by this subsection.
Frequently asked questions
What does “comply with ASME B31.3” mean in practice?
It means the piping system’s design, materials, fabrication, examination and testing should be consistent with the ASME B31.3 process piping standard; the Code requires that compliance explicitly in § 1406.1.
Can I use piping that is not listed to ASME B31.3 if the manufacturer provides ratings?
No — § 1406.1 requires compliance with ASME B31.3. Manufacturer pressure/temperature ratings are necessary but do not replace the ASME B31.3 requirement.
Are there numeric pressure/temperature limits in § 1406.1?
No. § 1406.1 requires that materials be rated for your system’s operating pressures and temperatures; it does not set numeric thresholds itself. Use manufacturer data and ASME B31.3 to determine acceptability.
If my piping is approved to ASME B31.3, do I still have to follow manufacturer installation instructions?
Yes — the Code mandates both: compliance with ASME B31.3 and installation in accordance with the manufacturer’s instructions (both are required by § 1406.1).
Where do I find additional rules for hazardous fluids?
See § 1406.2 for Hazardous Process Piping requirements (identification, visibility, containment).
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