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ASME B16.24-2016 — Cast Copper Alloy Pipe Flanges, Flanged Fittings, and Valves (Classes 150-2500)
⚙️ ASME B16.24-2016 specifies pressure-temperature ratings, nominal sizes, methods of designating openings, marking, materials, dimensions, bolting and gasket requirements, tolerances, and pressure testing for cast copper alloy pipe flanges, flanged fittings, and valves in Classes 150, 300, 600, 900, 1500, and 2500. Compared with carbon steel and stainless steel systems, cast copper alloy flanges and valves offer outstanding resistance to seawater and fresh water, so they are widely used in shipbuilding, offshore engineering, seawater cooling, fire-water systems, and building water supply. Maintained by the ASME B16 Committee, the Standard is the core reference for selection and acceptance of copper alloy flanged products.
💡 Unlike B16.5 (carbon, alloy, and stainless steel flanges), B16.24 is limited to cast copper alloy products and provides dedicated copper alloy pressure-temperature rating tables. Never apply B16.5 ratings directly to copper alloy flanges.
1. Scope and General Framework 📌
The Standard covers cast copper alloy pipe flanges, flanged fittings, and valves in Classes 150 through 2500, and defines the methods of designating sizes and openings. The body has 11 sections: Scope, General, Pressure-Temperature Ratings, Size and Method of Designating Openings, Marking, Materials, Flange and Valve Body Dimensions, Fitting and Valve Dimensions, Bolting and Gaskets, Tolerances, and Pressure Testing.
- Pressure-temperature ratings (Section 3): tables by material, e.g., ASTM B61 Alloy C92200 (tin bronze) and ASTM B62 Alloy C83600 (semi-red brass).
- Size and openings (Section 4): Fig. 1 gives the method of designating outlets of reducing fittings.
- Bolting and gaskets (Section 9): requirements for matching bolts and gaskets.
- Pressure testing (Section 11): requirements for finished valves and fittings.
Because cast copper alloy flanges, flanged fittings, and valves are used mainly in moderate-pressure, corrosion-critical seawater, fresh water, fuel, and lube oil systems, their rating tables differ markedly from carbon steel systems; engineers must read the copper alloy tables in Section 3.
⚠️ B16.24 applies only to cast copper alloy products. If media or temperature exceed the copper alloy range (e.g., high-temperature steam), use carbon or alloy steel flanges (such as B16.5) — never substitute on the basis of similar appearance.
2. Pressure-Temperature Ratings and Materials 🔥
Rating tables are provided by alloy. Table 1 lists ratings for ASTM B61 Alloy C92200 and ASTM B62 Alloy C83600; Tables 2 and 3 give Class 150 through 2500 ratings for C92200 and C83600 respectively. Higher classes cover smaller size ranges, and allowable stress falls as temperature rises, reducing permitted working pressure.
| Item | Content | Notes |
|---|---|---|
| Materials | ASTM B61 C92200, ASTM B62 C83600 | Cast copper alloys, excellent corrosion resistance |
| Classes | 150, 300, 600, 900, 1500, 2500 | Higher class, smaller size range |
| Rating tables | Separate tables by alloy and class | Based on allowable stress |
| Typical temperature range | Ambient to moderate temperature | High-temperature duty requires steel flanges |
| Pressure testing | Per Section 11 | Verifies sealing and strength |
⚠️ Copper alloy allowable stress decreases with temperature. Always size on the rating at design temperature, not the ambient rating, and check the size tables — some classes are not available in large sizes.
3. Dimensions, Opening Designation, and Marking 📏
Sections 7 and 8 specify flange and valve body dimensions and fitting and valve dimensions, and Fig. 1 defines how reducing fitting outlets are designated. The dimensional system is coordinated with the B16.1/B16.5 series, but ratings are given separately for copper alloys. Section 5 (Marking) requires the manufacturer’s name or trademark, material, class, and size on each product for traceability.
| Class | Typical Size Range | Typical Products | Typical Systems |
|---|---|---|---|
| Class 150 | Small to medium sizes | Plate and hub flanges, gate/globe valves | Seawater cooling, fire water, building supply |
| Class 300 | Small to medium sizes | Flanged fittings, valves | Ship seawater lines, cooling systems |
| Class 600 | Smaller sizes | High-pressure copper alloy valves | Hydraulic and fuel systems |
| Class 900-2500 | Mainly small sizes | High-pressure valve bodies and flanges | Special high-pressure seawater/hydraulic service |
💡 Copper alloy flanges, valves, and fittings should be used as a matched set: same class and size products built to this Standard are interchangeable. When mating to steel flanges, verify bolt-circle diameter, facing type, and gasket material to avoid galvanic corrosion or leaks.
4. Bolting, Gaskets, and Tolerances 🔩
Section 9 requires bolts matched to the copper alloy flange to avoid galvanic corrosion and gaskets compatible with the facing type. Section 10 sets dimensional tolerances for flange thickness, outside diameter, and bolt holes to ensure installation accuracy. Section 11 sets pressure testing to verify sealing and strength at rated pressure.
🚨 Direct contact between copper alloy flanges and steel bolts or steel piping invites galvanic corrosion. For critical seawater systems use insulating gaskets, insulating sleeves, or dedicated anti-galvanic bolting, and inspect periodically.
5. Engineering Practice Essentials 🛠️
- 🔍 Selection workflow: identify media (seawater/fresh water/oil) and design temperature and pressure → read the copper alloy rating table → determine class and size → match flange type, gasket, and bolts.
- 🔧 Installation: align facings and tighten bolts in a cross pattern evenly to avoid distorting the copper alloy flange; use gaskets compatible with the media.
- 📊 Pressure testing: shell and seat tests per the Standard before installation; confirm no leakage before commissioning.
- 📋 Traceability: verify manufacturer, material, and class markings; request material certificates and pressure-test records.
6. Frequently Asked Questions ❓
❓ Q: What is the difference between B16.24 and B16.5?
A: B16.5 covers carbon, alloy, and stainless steel flanges (NPS 1/2–24); B16.24 covers cast copper alloy flanges, flanged fittings, and valves (Classes 150–2500). Materials and rating systems differ — copper alloy products must use the B16.24 tables.
A: B16.5 covers carbon, alloy, and stainless steel flanges (NPS 1/2–24); B16.24 covers cast copper alloy flanges, flanged fittings, and valves (Classes 150–2500). Materials and rating systems differ — copper alloy products must use the B16.24 tables.
❓ Q: Why are copper alloy flanges common in seawater systems?
A: Cast copper alloys such as C92200 and C83600 resist seawater and fresh water corrosion well and have adequate strength, making them common in ships, offshore platforms, and seawater cooling; they are not suitable for high-temperature steam.
A: Cast copper alloys such as C92200 and C83600 resist seawater and fresh water corrosion well and have adequate strength, making them common in ships, offshore platforms, and seawater cooling; they are not suitable for high-temperature steam.
❓ Q: How are B16.24 valves pressure tested?
A: Per Section 11, shell strength and seat tightness tests are performed at the specified pressures and durations; only valves that pass may be installed.
A: Per Section 11, shell strength and seat tightness tests are performed at the specified pressures and durations; only valves that pass may be installed.
🔍 Q: Can copper alloy flanges connect directly to steel piping?
A: Yes, but take anti-galvanic measures (insulating gaskets, insulating bolt sleeves, etc.) and verify bolt-hole and facing dimensions to prevent corrosion or leakage.
A: Yes, but take anti-galvanic measures (insulating gaskets, insulating bolt sleeves, etc.) and verify bolt-hole and facing dimensions to prevent corrosion or leakage.
