Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
ASME B16.29-2017 — Wrought Copper and Wrought Copper Alloy Solder-Joint Drainage Fittings — DWV
🚽 ASME B16.29-2017 is the American National Standard for wrought copper and wrought copper alloy solder-joint drainage fittings (DWV — Drain, Waste, and Vent), issued December 29, 2017, as a revision of ASME B16.29-2012. The Standard defines the dimensions, types, laying lengths, pitch (slope), threaded-end requirements, materials, marking, ovality limits, and gaging methods of DWV solder-joint fittings, which are used extensively in building soil, waste, and vent piping systems.
💡 The key difference between DWV fittings and pressure solder-joint fittings (B16.22): DWV systems operate at no pressure or negligible pressure and rely on gravity flow, so the Standard specifies shallower solder cups in the larger sizes — since pressure containment strength is not the controlling factor, this saves material and speeds assembly.
1. Scope and General Framework 📌
This Standard was developed by Subcommittee J (Solder-Joint Fittings) of the ASME B16 Committee, with dimensions stated in U.S. Customary units. Historically, standardization of drainage fittings began with ASA A40.3-1941 under Sectional Committee A40, moved to the B16 Committee around 1949, and the wrought drainage fitting standard was first published as MSS SP-64-1961, later approved as ASA B16.29-1966. Subsequent revisions appeared in 1973, 1980, 1986, and 1994 — the 1994 edition removed inspection tolerance requirements, established minimum laying lengths, and added soil pipe adapters — followed by the 2012 and 2017 editions.
Section 1 (Scope) defines the coverage as wrought copper and wrought copper alloy solder-joint drainage fittings for soil, waste, and vent systems, including elbows, tees, 45° Y branches, caps, couplings, bushings, adapters, closet flanges, trap adapters, vent increasers, and slip-joint ends.
⚠️ DWV fittings are not intended for pressurized systems. If DWV fittings are used in lines under internal pressure (for example recirculating hot water or sanitary hot-water service), the shallower cups and thinner walls may not satisfy pressure requirements — switch to ASME B16.22 pressure solder-joint fittings instead.
2. Technical Requirements and Specifications 🔧
Sections 4 through 14 of the Standard establish a complete set of technical requirements:
- Pitch (Slope) (Sec. 4): the required slope of drainage piping so that sewage flows under gravity without trapping.
- Component Size (Sec. 6): the method of designating nominal sizes, based on the copper tube outside diameter series common to DWV service (e.g., 1-1/4, 1-1/2, 2, 3, 4 in).
- Material (Sec. 8): fittings may be made of phosphorized (deoxidized) copper (e.g., CDA 122) or compatible copper alloys, intended for use with copper tube such as ASTM B88.
- Laying Lengths and Ovality (Secs. 9, 10): dimensional tolerances for laying lengths and limits on end ovality.
- Threaded Ends (Secs. 11, 12): thread types and design requirements for fittings with threaded ends used to transition to iron or steel pipe.
- Alignment and Gaging (Secs. 13, 14): end alignment requirements and gage inspection of threaded ends.
| Fitting Type | Typical Sizes (in) | End Configuration | Typical Use |
|---|---|---|---|
| Solder-joint elbow | 1-1/4 – 4 | Cup × cup | Direction changes in horizontal and vertical runs |
| 45° Y branch | 1-1/4 – 4 | Cup × cup × cup | Branch entry into main drain in direction of flow |
| Tee | 1-1/4 – 4 | Cup × cup × cup | Junctions of stacks and horizontal drains |
| Closet flange | 3, 4, etc. | Cup × flange plate | Connecting water closets to soil stacks |
| Soil pipe adapter | 1-1/2 – 4 | Cup × no-hub/spigot | Transition between copper tube and cast-iron no-hub pipe |
| Vent increaser | 1-1/4 – 2 steps | Cup × cup (reducing) | Enlarging vent stack sizes |
🚨 Solder-joint quality determines system life: the copper tube must be inserted to the full cup depth with the prescribed clearance, and solder must fill the entire joint circumferentially. Overheating or underheating causes leaks, and rework on concealed drainage work is extremely costly.
3. Dimensions and Tolerances 📏
Sections 1–14 give the general requirements, Mandatory Appendix I provides all U.S. Customary dimension tables, and Appendix II lists references. The dimension tables include: Table 1 solder-joint ends, Table 2 DWV threaded ends, Table 3 couplings, extended bushings, and adapters, Table 4 soil pipe adapters, Table 5 DWV cup × no-hub soil pipe adapters, Table 6 elbows, Table 7 45° Y’s, Table 8 tees, Table 9 caps, Table 10 vent increasers, Table 11 closet flanges, Table 12 trap adapters, and Table 13 slip-joint ends.
The key parameters of solder-joint ends (Table 1) are cup inside diameter, cup depth, and the clearance for the tube end. The larger DWV sizes use shallower cups to save copper and ease assembly. Threaded ends (Table 2) generally follow the pipe thread form of ASME B1.20.1 and are verified by gaging (Sec. 14) to ensure interchangeability.
| Nominal Size (in) | Cup Inside Diameter (typical) | Cup Depth (DWV typical) | Verification |
|---|---|---|---|
| 1-1/4 | ≈ 1.400 | Shallow cup | Gaging / insertion check |
| 1-1/2 | ≈ 1.650 | Shallow cup | Gaging / insertion check |
| 2 | ≈ 2.165 | Shallow cup | Gaging / insertion check |
| 3 | ≈ 3.190 | Shallow cup | Gaging / insertion check |
| 4 | ≈ 4.240 | Shallow cup | Gaging / insertion check |
4. Marking, Materials, and Quality Systems 🏷️
Section 7 requires fittings to be clearly marked with the manufacturer’s name or trademark and material identification to ensure traceability. For materials, wrought copper fittings are typically made of phosphorized deoxidized copper (CDA 122/DHP) or matching ASTM copper-alloy grades; brazing should use compatible copper-phosphorus or silver filler metals with appropriate flux. Nonmandatory Appendix A describes a manufacturer quality-system program, so purchasers may request conformance statements and material certificates.
💡 Procurement tip: use one supplier chain for the DWV fittings, copper tube, and solder on a given project, and verify conformance documents. Products of established brands are manufactured to B16.29 and are dimensionally interchangeable, but always check markings and lot certificates.
5. Engineering Practice Essentials 🛠️
- 🔍 Pitch control: lay out horizontal drainage runs at the required slope and avoid reverse slope, which causes deposits and blockages; DWV systems are sensitive to installation slope.
- 🔧 Brazing practice: preheat the cup uniformly (oxy-acetylene or propane) before feeding solder, and rely on capillary action to fill the annulus; avoid solder flowing into the pipe and forming a wad that obstructs flow.
- 📊 Stacks and vents: vents maintain pressure balance during drainage to protect traps from siphonage; vent increasers enlarge vent stacks where required.
- 📋 Testing: perform water-fill and flow tests before concealing piping to verify the seal of every cup and threaded joint.
6. Frequently Asked Questions ❓
❓ Q: What is the difference between B16.29 and B16.23?
A: B16.29 covers wrought copper and copper alloy DWV fittings, while B16.23 covers cast copper alloy solder-joint drainage fittings. The types are similar but the manufacturing process and wall thickness differ, so the two are not interchangeable against the same dimension table.
A: B16.29 covers wrought copper and copper alloy DWV fittings, while B16.23 covers cast copper alloy solder-joint drainage fittings. The types are similar but the manufacturing process and wall thickness differ, so the two are not interchangeable against the same dimension table.
❓ Q: Why are DWV cups shallower than those of pressure fittings?
A: DWV systems carry no internal pressure and drain by gravity, so pressure strength is not the controlling factor; a shallower cup saves material, speeds assembly, and still provides a sound soldered connection.
A: DWV systems carry no internal pressure and drain by gravity, so pressure strength is not the controlling factor; a shallower cup saves material, speeds assembly, and still provides a sound soldered connection.
❓ Q: Can DWV fittings be used in pressure piping?
A: No. For pressurized service select ASME B16.22 pressure solder-joint fittings or equivalent rated products; the thinner walls and shallower cups of DWV fittings do not satisfy pressure requirements.
A: No. For pressurized service select ASME B16.22 pressure solder-joint fittings or equivalent rated products; the thinner walls and shallower cups of DWV fittings do not satisfy pressure requirements.
🔍 Q: How are threaded-end fittings used?
A: Threaded ends transition between copper tube and iron/steel pipe or other threaded devices; threads conform to ASME B1.20.1 pipe thread and are verified by gaging, installed with suitable thread sealants.
A: Threaded ends transition between copper tube and iron/steel pipe or other threaded devices; threads conform to ASME B1.20.1 pipe thread and are verified by gaging, installed with suitable thread sealants.
