2.2 Approved Piping Materials, Joints & Connections

2.2 Approved Piping Materials, Joints & Connections

A central responsibility of the plumbing plans examiner is verifying that all specified piping materials, fittings, and joining methods appear in the material tables of Chapter 6 (Water Supply and Distribution: Tables 605.3, 605.4 and 605.5) and Chapter 7 (Sanitary Drainage: Tables 702.1 through 702.4), and that the joints follow Sections 605 and 705. Specifying unlisted materials or incompatible joints leads to catastrophic mechanical failures, potable water contamination, and property damage.

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Material Identification and Certification (IPC Section 303)

Under IPC 303.1, each length of pipe and each pipe fitting, trap, fixture, material and device must bear the manufacturer's identification and any markings the referenced standard requires. Plastic pipe, fittings and components must be third-party certified as conforming to NSF 14 (IPC 303.3). Under IPC 303.4, products required to comply with a referenced standard must be listed by a third-party certification agency, and IPC 303.5 requires cast-iron soil pipe, fittings and couplings to be third-party listed and labeled. The marking and certification are what let an examiner confirm that the specified product matches a standard listed in the code's material tables.

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Metallic Water & Drainage Piping Systems

1. Copper Tubing (ASTM B88 & ASTM B306)

Copper tubing is color-coded by wall thickness, which determines its allowable operating pressures and mechanical durability:

• Type K (Green Marking): Heaviest wall. Often specified for underground water services and high-pressure risers, and available in annealed coils or hard-drawn lengths.
• Type L (Blue Marking): Medium wall. A common specification for interior commercial hot and cold water distribution.
• Type M (Red Marking): Thinnest pressure-rated wall. IPC Table 605.3 lists Types K, WK, L, WL, M and WM copper tubing for water service, and Table 605.4 lists them for water distribution. A rule against Type M underground is a local amendment or project specification, not a model-code requirement.
• Type DWV (Yellow Marking - ASTM B306): Thin wall for drainage, waste and vent piping (IPC Table 702.1). It is not listed in Tables 605.3 or 605.4, so it may not be used for water service or distribution.

2. Cast Iron Soil Pipe (ASTM A74 & CISPI 301)

Cast iron remains the premier material for sanitary drainage and acoustic dampening in commercial, healthcare, and multi-family construction:

• Hub-and-Spigot Pipe (ASTM A74): Available in Service Weight (SV) and Extra Heavy (XH). Spigot ends seat into hub bells fitted with compression elastomeric gaskets conforming to ASTM C564 (or historically lead and oakum, now rare in new construction).
• Hubless (No-Hub) Pipe (CISPI 301): Smooth-ended pipe joined by elastomeric neoprene sleeves wrapped in corrugated stainless steel shields with band clamps conforming to CISPI 310 (standard 2-band) or ASTM C1277 / ASTM C1540 (heavy-duty 4-band and 6-band couplings for high-vibration or high-rise installations).

3. Other Metallic Materials

• Ductile Iron Water Pipe (AWWA C151/A21.51, AWWA C115/A21.15): Listed in Table 605.3 for water service. It is usually cement-mortar lined and joined with push-on or mechanical joints.
• Galvanized Steel Pipe (ASTM A53): Listed for water service and distribution, but rarely specified today because of internal scaling. Joints to copper need a copper-alloy, dielectric or insulating fitting (IPC 605.23.1).
• Stainless Steel (Types 304/304L and 316/316L; ASTM A269, A312, A778): Listed in Tables 605.3 and 605.4 and used for high-purity water, chemical waste and press-connect systems.

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Plastic Water & Drainage Piping Systems

1. Polyvinyl Chloride (PVC-DWV)

• Solid Wall PVC (ASTM D2665): High-rigidity thermoplastic drainage, waste, and vent pipe. Universally approved for sanitary drainage above and below ground.
• Cellular Core PVC (ASTM F891): Co-extruded pipe featuring solid outer and inner skins with a foamed cellular plastic core. Highly cost-effective and lightweight, but plans examiners must verify local municipal amendments, as many commercial jurisdictions restrict cellular core pipe in fire-resistance-rated assemblies or multi-story buildings.

2. Acrylonitrile Butadiene Styrene (ABS-DWV)

• Solid Wall ABS (ASTM D2661) & Cellular Core ABS (ASTM F628): Black rigid plastic used exclusively for DWV systems. Has high impact resistance at freezing temperatures.

3. Cross-Linked Polyethylene (PEX - ASTM F876/F877)

PEX is the predominant material for residential and light-commercial water distribution:

• Ratings: Standard hydrostatic ratings of $160\text{ psi}$ at $73.4^\circ\text{F}$, $100\text{ psi}$ at $180^\circ\text{F}$, and $80\text{ psi}$ at $200^\circ\text{F}$.
• Manufacturing Classifications: PEX-a (peroxide method, $>85\%$ cross-linking, highest flexibility and thermal shape memory), PEX-b (silane method, $65\text{--}70\%$ cross-linking), and PEX-c (electronic beam radiation, $70\text{--}75\%$ cross-linking).
• Fittings Standards: ASTM F1807 (metal insert with copper crimp rings), ASTM F2159 (plastic insert), ASTM F1960 (cold expansion with PEX reinforcing rings / ProPEX), and ASTM F2080 (cold expansion with compression sleeve).

4. Chlorinated Polyvinyl Chloride (CPVC - ASTM D2846 / ASTM F441 / ASTM F442)

Approved for hot and cold water distribution with a typical rating of $100\text{ psi}$ at $180^\circ\text{F}$. Schedule 40 and 80 CPVC is used in commercial applications.

Lead content (IPC 605.2 and 605.2.1). Pipe, fittings, valves and faucets in the water supply system may contain not more than 8 percent lead. Products that supply water for drinking or cooking must comply with NSF 372 and have a weighted average lead content of 0.25 percent or less.

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Code-Approved Joining Methods & Standards

   +--------------------------------------------------------------------------+
   |                  SUMMARY OF PERMITTED JOINTS BY MATERIAL                 |
   +----------------------+---------------------------+-----------------------+
   | Material             | Approved Joint Method     | Standard Specification|
   +----------------------+---------------------------+-----------------------+
   | PVC-DWV              | Solvent Cement & Primer   | ASTM D2564 / F656     |
   | ABS-DWV              | Solvent Cement (NO Primer)| ASTM D2235            |
   | Copper Tubing        | Solder (Lead-Free <=0.2%) | ASTM B32 / ASTM B813  |
   | Copper Tubing        | Brazing (Melting >1000°F) | AWS A5.8 (BCuP series)|
   | Copper Tubing        | Press-Connect (EPDM seal) | ASME B16.51           |
   | Copper / CPVC / PEX  | Push-Fit                  | ASSE 1061             |
   | Cast Iron (Hubless)  | Shielded Coupling         | CISPI 310 / ASTM C1277|
   | Ductile Iron         | Push-On / Mechanical      | AWWA C111 / C606      |
   +----------------------+---------------------------+-----------------------+

Solvent Welding Requirements & The Dissimilar Plastics Rule

1. PVC Primer Requirement (IPC Sections 605.21.3 and 705.10.2): For PVC water piping and PVC DWV piping, joint surfaces must be clean and dry, a purple primer conforming to ASTM F656 must be applied, and then a solvent cement that is not purple and conforms to ASTM D2564 (or a listed CSA standard) is applied to all joint surfaces while the primer is wet. Joints follow ASTM D2855. The 2024 IPC text for these sections contains no exception that omits the primer, so a plan note calling for "one-step" cement without primer on PVC should be questioned.
2. ABS Cementing (IPC 705.2.2): ABS joints use solvent cement conforming to ASTM D2235 (or CSA B181.1) applied to clean, dry joint surfaces. The code does not call for a primer on ABS.
3. The Dissimilar Plastics Rule: IPC 605.9 (water) and IPC 707.1 (drainage) prohibit solvent-cement joints between different types of plastic pipe. Under IPC 705.16.4, joints between different types of plastic drainage pipe must use an approved adapter fitting. The only exception is a single joint between ABS and PVC at the end of the building drain and the beginning of the building sewer, made with transition solvent cement complying with ASTM D3138. Mechanical joints between different drainage materials follow ASTM C1173, C1460 or C1461 (IPC 705.16).

Soldering, Brazing & Lead-Free Mandates

• Lead-free solder and flux (IPC 605.12.3 and 605.13.6): Water supply piping must be joined with lead-free solder and fluxes, where "lead free" means 0.2 percent lead or less. Solder and flux for drinking-water piping must also conform to NSF 61.
• Lead in pipe and fittings (IPC 605.2.1): Products supplying drinking or cooking water must comply with NSF 372, with a weighted average lead content of 0.25 percent or less. The federal Safe Drinking Water Act uses the same definitions.
• Soldered Joints: Joints are made per ASTM B828, with tube ends reamed, flux conforming to ASTM B813, and solder conforming to ASTM B32.
• Brazed Joints: Filler metals conforming to AWS A5.8 (typically BCuP phosphorus-copper alloys) melt above $840^\circ\text{F}$ ($449^\circ\text{C}$), the point that separates brazing from soldering. Medical gas piping is brazed under NFPA 99, which the IPC references for those systems.

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Code-Prohibited Joints & Piping Connections

The plans examiner must flag and reject the joints prohibited by IPC 605.9 (water supply) and IPC 707.1 (drainage):

Two related rules round out the list:

1. Saddle-Type Fittings: Saddle valves clamped onto a pipe to feed an ice maker or humidifier pierce the pipe wall and rely on a gasket. They are prohibited on both water and drainage piping.
2. Slip Joints (IPC 405.9 and 1002.2): Slip joints must use an approved elastomeric gasket and may be installed only on the trap inlet, the trap outlet and within the trap seal. Where a fixture has concealed slip-joint connections, an access panel or utility space at least 12 inches in its smallest dimension (or another approved arrangement) must give access for inspection and repair.

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Plan Examiner Checklist: Approved Materials & Joint Verification

1. Lead-Free Compliance: Do drinking-water valves, fittings and faucets comply with NSF 372 ($0.25\%$ weighted average lead), and does the solder specification call for lead-free solder and flux ($0.2\%$ lead or less)?
2. Material Listing: Does each specified pipe appear in the correct table: Table 605.3 for water service, Table 605.4 for distribution, and Tables 702.1 through 702.3 for drainage? Type DWV copper, for example, is not listed for water piping.
3. Primer & Solvent Specification: Are PVC-DWV joints specified with ASTM F656 purple primer and ASTM D2564 cement? Is solvent welding between dissimilar PVC and ABS avoided?
4. Cast Iron Couplings: In multi-story cast iron drainage stacks, are CISPI 310 or ASTM C1277/C1540 heavy-duty shielded couplings specified rather than unshielded rubber boots?
5. Prohibited Joints Check: Are saddle-type fittings, cement joints, unapproved fittings and solvent joints between different plastics absent, and are slip joints only at trap inlets and outlets, with access where concealed?