8.2 Joints, Connections & Transitions Between Materials (SPS 384.40)
Key Takeaways
Cement or concrete joints, mastic or hot-poured bituminous joints, rolling O-rings between different pipe sizes, solvent joints between different plastics (except ABS to PVC non-pressure) and roll-grooved galvanized pipe are prohibited.
Caulked lead joints are packed with oakum or hemp and poured in one operation at least 1 inch deep, ending no more than 1/8 inch below the hub rim; drain caulked joints are allowed only in vertical positions.
PVC solvent joints use ASTM F656 primer and ASTM D2564 cement; water supply primer and cement must carry NSF 14 certification.
Threaded plastic joints are allowed only on Schedule 80 or heavier pipe, with joint compound or tape on male threads only.
Dissimilar metals must be protected against galvanic current with dielectric unions (ASSE 1079), flanges (ASME B16.24) or listed transition fittings.
General rules (SPS 384.40 (1))
Every joint must be watertight and gastight to the greater of the test or design requirement. Pipe ends are prepared per the pipe standard or manufacturer. Unless another rule allows them, these joints are prohibited:
- Cement or concrete joints
- Mastic or hot-poured bituminous joints
- Elastomeric rolling O-rings between pipes of different diameters
- Solvent-cement joints between different types of plastic, except ABS to PVC in non-pressurized systems
- Roll-grooving of galvanized steel pipe
Joining methods by material
| Material | Permitted joints | Key details |
|---|---|---|
| ABS | Mechanical (push-on DWV per ASTM D3212); solvent (ASTM D2235); threaded | Threads only on Schedule 80 or heavier, cut with plastic-pipe dies; lubricant on male threads only |
| Black steel | Threaded (ASME B1.20.1); mechanical; caulked (DWV only); welded | Compound or tape on male threads only |
| Brass | Brazed (AWS A5.8); mechanical; soldered (ASTM B32); threaded | Surfaces cleaned bright by non-chemical means; lead-free for water |
| Cast iron | Caulked; mechanical; threaded | DWV push-on gaskets ASTM C564; no-hub sleeves ASTM C564, CISPI 310 or FM 1680; water push-on AWWA C111, no lead-tipped gaskets |
| CPVC | Mechanical (ASTM D3139 for water); solvent (ASTM D2846, F493 or F3328); threaded on Schedule 80 | F493 cement; NSF 14 primer and cement for water |
| Copper | Brazed; flared on annealed tubing only, with a flaring tool; mechanical; soldered per ASTM B828 with NSF-approved flux; threaded | Lead-free materials for water |
| Ductile iron | Mechanical (AWWA C111, no lead-tipped gaskets); threaded | - |
| Galvanized steel | Threaded; mechanical; caulked (DWV only) | No roll grooving |
| PE | Heat fusion (ASTM F2620); mechanical (ASTM D3139 for water) | Joint left undisturbed until cool |
| Other polyolefins | Heat fusion per ASTM D2657 | - |
| PEX | Per manufacturer's instructions | Fittings from Table 384.30-9 |
| PVC | Mechanical (DWV ASTM D3212; water ASTM D3139); solvent (ASTM D2855 or F3328); threaded on Schedule 80 | F656 primer and D2564 cement; NSF 14 for water |
| Stainless steel | Mechanical; threaded; welded | - |
| Lead | Burned or wiped | Wiped joint at least 3/4 inch exposed each side and 3/8 inch thick |
Solvent cements are handled per ASTM F402. Joint surfaces must be clean and dry, and the joint must be made while the cement is wet.
Caulked lead joints
For hub-and-spigot DWV pipe, the joint is:
- Packed firmly with oakum or hemp.
- Poured with molten lead in one operation, at least 1 inch deep, ending no more than 1/8 inch below the rim.
- Caulked tight.
- Not painted or coated until tested and approved.
Caulked joints in drain piping may be used only in a vertical position; in vent piping, vertical or horizontal. For cast iron water pipe, the bell is packed with treated paper rope and poured 2-1/2 inches deep.
Transitions between materials (SPS 384.40 (16))
Different materials are connected with mechanical compression joints installed per the manufacturer, or by the specific methods below. Dissimilar metals must be protected from galvanic current and stray currents:
- Dielectric nipples: ASME B1.20.1 or ASTM A53
- Dielectric unions: ASSE 1079
- Dielectric flanges: ASME B16.24
- Dielectric transition fittings: NSF 61 and NSF 372
| Connection | Method |
|---|---|
| Copper to cast iron | Caulked joint or threaded fitting |
| Cast iron to steel or brass | Caulked or threaded joint |
| Plastic to cast iron | Caulked or threaded joint |
| Plastic to other plastic, or plastic to other non-cast-iron material | Threaded joint per the PVC threaded-joint rule (Schedule 80), unless ABS to PVC below |
| Lead to other materials | Adapter fitting, with the lead caulked or burned to it |
| ABS to PVC, non-pressurized | Solvent weld: ASTM F656 primer on the PVC surfaces, ASTM D3138 transition cement, handled per F402 |
Fixtures and concrete structures (SPS 384.40 (17) and (18))
- Flanged fixtures with integral traps, such as water closets, are mechanically fastened to a compatible fitting and sealed with a watertight gasket or setting compound.
- Pipe-to-concrete connections use resilient connectors:
- ASTM C923 for manholes
- ASTM F2510 for corrugated PE or PP pipe at manholes
- ASTM C1644 for on-site wastewater tanks
- ASTM C1478 for storm structures
- ASTM C564 gaskets for cast iron
Worked examples
- A plumber joins a new PVC drain to an existing ABS building drain in a house, a non-pressurized system. The solvent weld is allowed with PVC primer and an ASTM D3138 transition cement. Using regular PVC cement without the D3138 transition product would not comply.
- A copper water line meets a galvanized steel line. A dielectric union meeting ASSE 1079 (or another listed dielectric fitting) is needed to stop galvanic corrosion.
- A 3-inch no-hub cast iron horizontal drain joint has no alignment shield. It must be supported within 24 inches on each side (SPS 382.60 (2) (b), section 8.3).
- An installer roll-grooves galvanized pipe for a quick coupling. This is prohibited: use threaded or other approved mechanical joints.
Which joint is prohibited by SPS 384.40 (1) (c)?
A heat-fusion PE joint
A flared joint on annealed copper
A roll-grooved joint on galvanized steel pipe
A no-hub joint with a CISPI 310 coupling
A caulked lead joint is made on hub-and-spigot cast iron drain pipe. What is the minimum depth of poured lead?
1/2 inch
1 inch
2 inches
2-1/2 inches
On what pipe may threaded joints be used for PVC, ABS or CPVC plastic pipe under SPS 384.40?
Schedule 80 or heavier pipe only
Any schedule if Teflon tape is used
Schedule 40 drain pipe only
Only on pipe 1 inch and smaller
Sections you finish are checked off in the contents.