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ASME B16.32-1992 scan — Cast Copper Alloy Solder Joint Fittings for Sovent Drainage Systems
🏗️ ASME B16.32-1992 is the Standard Committee’s dedicated document for cast copper alloy solder joint DWV (Drain-Waste-Vent) fittings used on self-aerating one-pipe Sovent drainage systems. Approved as an American National Standard on February 28, 1992, it superseded the 1984 edition and runs to 16 pages. The Sovent system was developed in Switzerland in 1961, patented in the United States in late 1969 for high-rise development, and standardized first by MSS SP-74 (1970), before being submitted to the B16 Committee and approved by ANSI in January 1973. Because the available PDF is a scan, this article is compiled from the standard’s contents, scope, and body digest.
💡 Core idea of the Sovent system: specialized aerator and deaerator fittings let the air and water in a drainage stack regulate each other’s flow automatically — “single-pipe drainage with self-venting” — eliminating the dedicated vent stack and saving building space and material.
1. Scope and Coverage 📌
This Standard covers cast copper alloy solder joint DWV fittings used in buildings employing the self-aerating one-pipe Sovent system and operating under full fixture load. It specifies the following:
- Description — the functional definition and design basis of the fittings;
- Pitch — required downward slope of drainage openings;
- Sizes and methods of designating openings, especially for reduced fittings;
- Marking, material, and metal thickness;
- Design features and tests.
U.S. customary units are the standard; conversion to SI is 1 in. = 25.4 mm (not applicable to drainage tube size). Fitting sizes correspond to the drainage tube size shown in ASTM B306.
⚠️ The Standard cautions that the configurations shown in Figs. 3 and 4 are critical and are based on careful testing; all connections are female solder joint fitting ends made to receive copper tube diameter and conforming to Table 1 of ASME B16.23.
2. Fitting Types and Designation of Openings 🔧
The Standard divides Sovent fittings into two main categories, each with its own designated opening convention:
| Fitting Category | Function | Typical Configuration | Figure |
|---|---|---|---|
| Aerator fitting | Introduces air into the drainage stack and breaks up water slugs for automatic venting | Cast copper alloy tee-type fitting with angled inflow branch | Fig. 3 |
| Deaerator fitting | Releases air at the base of the stack and separates the air flow | Reducing fitting with vent connection | Fig. 4 |
| Pressure equalizing connections | Balances pneumatic pressure and protects trap seals | Dedicated branch connection to the vent path | Standard table |
Openings of reduced fittings are designated in the prescribed sequence and direction so that each connection aligns with the correct drainage and venting flow path.
3. Technical Requirements and Tests 📏
All nominal 90-deg. drain openings must be pitched to produce a downward slope of 1/4 in./ft (2.1%), as shown in Fig. 3. Materials are cast copper alloy with metal thickness adequate for solder joint connection strength and corrosion resistance.
| Item | Requirement | Remarks |
|---|---|---|
| Pitch of drain openings | Approx. 1/4 in./ft (2.1%) downward for 90-deg. openings | Ensures self-cleaning velocity and venting |
| Fitting size | Corresponds to ASTM B306 drainage tube size | Socket ends made to copper tube diameter |
| Connection type | All female solder joint ends | Per ASME B16.23 Table 1 |
| Material | Cast copper alloy | Corrosion resistant, solderable |
| Metal thickness | Minimum wall per standard tables | Strength plus standard socketing allowance |
| Tests | Per Section 9 of the Standard | Verifies hydraulic and pneumatic performance |
🚨 Installation orientation is critical: aerator fittings belong at the top and deaerator fittings at the bottom of the stack. Reversing them destroys the self-venting balance, allowing water slugs to form, trap seals to be siphoned, and potential sewage backup or odor escape.
4. Engineering Practice Essentials 🛠️
- 🔍 System selection: Sovent suits high-rise sanitary drainage; verify stack loading and venting capacity against applicable building and plumbing codes before specifying.
- 🔧 Soldering practice: use qualified solder and flux for copper alloy sockets, control heating temperature and insertion depth, and avoid overheating or unsound joints.
- 📊 Testing: the Standard requires verification under full hydraulic and pneumatic fixture load; conduct water and vent tests on site per code.
- 📋 Procurement marking: fittings must carry manufacturer identification, material grade, and size; verify opening designations on reducing fittings to prevent mixing.
5. Frequently Asked Questions ❓
❓ Q: What is a Sovent drainage system?
A: Sovent is a self-aerating single-stack drainage system originating in Switzerland in 1961. Dedicated aerator and deaerator fittings regulate two-phase air/water flow in one stack so a separate vent stack is not needed — ideal for high-rise buildings.
A: Sovent is a self-aerating single-stack drainage system originating in Switzerland in 1961. Dedicated aerator and deaerator fittings regulate two-phase air/water flow in one stack so a separate vent stack is not needed — ideal for high-rise buildings.
❓ Q: How do ASME B16.32 and B16.23 relate?
A: B16.32 governs the dedicated Sovent cast copper alloy fittings, whose socket end dimensions and connections must conform to Table 1 of ASME B16.23 (copper alloy DWV solder joint fittings). They are used together.
A: B16.32 governs the dedicated Sovent cast copper alloy fittings, whose socket end dimensions and connections must conform to Table 1 of ASME B16.23 (copper alloy DWV solder joint fittings). They are used together.
❓ Q: Is the scanned document consistent with the official standard?
A: This article is compiled from the scan’s contents, scope, and body digest; theme and structure follow the official text. Always verify design details against the current ASME publication.
A: This article is compiled from the scan’s contents, scope, and body digest; theme and structure follow the official text. Always verify design details against the current ASME publication.
❓ Q: Why does the Standard call the configurations “critical”?
A: The internal flow passages of aerators and deaerators determine air/water separation and pressure balance. These geometries were established through extensive testing, so dimensions must be followed exactly and configurations must not be altered.
A: The internal flow passages of aerators and deaerators determine air/water separation and pressure balance. These geometries were established through extensive testing, so dimensions must be followed exactly and configurations must not be altered.
6. Key Takeaways 📌
- Specialty standard: B16.32 is a focused document for one purpose — cast copper alloy solder joint fittings for self-aerating single-stack Sovent drainage systems — and should not be applied to general DWV fittings.
- Geometry rules: aerator and deaerator configurations are critical and dimension-controlled; all ends are female solder joint sockets sized to copper tube diameter per B16.23 Table 1.
- Pitch matters: nominal 90-deg. drain openings must slope downward about 1/4 in./ft (2.1%) so the stack self-scours and self-vents.
- System pairing: aerators belong down-system of the branch inlets and deaerators at the base; reversing them breaks the venting balance and can siphon trap seals.
- Verification: fittings are verified hydraulically and pneumatically at full fixture load; treat the scanned text as a summary and always confirm dimensions against the official ASME publication.
