Harris Stay-Silv 15 (part number 15620F5) is a phos-copper silver brazing alloy classified AWS A5.8 BCuP-5, packaged as a flat rod (0.050 in × 1/8 in / 1.3 × 3.2 mm) in a 5 lb (2.27 kg) tube — the preferred format for HVACR contractors and plumbing shops with high daily brazing volumes. The flat profile provides a larger contact area with the joint gap compared to round rod, promoting faster wetting and alloy flow into capillary clearances. Like all Stay-Silv 15 products, this alloy is self-fluxing on copper, contains 15% silver for improved joint ductility over zero-silver BCuP-2, and complies with AWS A5.8, ASME SFA-5.8, QQ-B-654A BCuP-5, and EU REACH and RoHS directives.
| Property | Value |
|---|---|
| AWS Classification | AWS A5.8 BCuP-5 |
| ASME Specification | ASME SFA-5.8 BCuP-5 |
| Other Standards | QQ-B-654A BCuP-5; ISO 17672 CuP 284; BS 1845-CP1 |
| Silver (Ag) | 14.5 – 15.5 % |
| Phosphorus (P) | 4.8 – 5.2 % |
| Copper (Cu) | Remainder (~80%) |
| Solidus | 1,190 °F (643 °C) |
| Liquidus | 1,480 °F (804 °C) |
| Melting Range | 290 °F (161 °C) |
| Rod Form | Flat — 0.050 in × 1/8 in (1.3 × 3.2 mm) |
| Package Weight | 5 lb (2.27 kg) tube |
| Part Number | 15620F5 |
| Flux Required (Cu-Cu) | Self-fluxing — no separate flux needed |
| Flux on Ferrous Metals | Required — use Harris Stay-Silv White Flux |
| Compliance | EU REACH; RoHS |
The 5 lb tube format is the standard choice for HVACR service companies, mechanical contractors, and wholesale distributors running high daily brazing volumes.
- HVACR service and installation — residential and commercial copper line sets, suction/liquid line brazed joints, filter-drier and sight glass connections
- Refrigeration OEM production — high-volume brazed copper assemblies on conveyor-based brazing lines
- Plumbing contractors — copper DWV and potable water systems requiring stronger joints than soft solder
- Boiler and hydronic heating — copper manifolds, headers, and zone valves in radiant and forced hot water heating systems
- Solar thermal — copper absorber plate assembly and collector loop piping
Stay-Silv 15 is available in three rod profiles — round (15520S), flat (15620F5), and strip (15S0051). The flat 0.050 × 1/8 in profile melts more evenly than round rod of similar cross-section, offering better control when bridging gaps or filling loose fittings. The flat profile also tends to deposit alloy in a more even layer along wider clearances. For extremely tight, close-tolerance joints, round rod provides faster capillary draw. For strip applications (pre-placed brazing), the 0.005 × 1 in strip (15S0051) is used.
Phosphorus in BCuP-5 acts as a flux on copper surfaces, dissolving copper oxide and allowing the molten alloy to wet clean copper without a separately applied flux. This reduces job time and eliminates the sticky, corrosive flux residue cleanup that silver alloys (BAg series) require. Note: BCuP-5 is not appropriate for brazing steel, stainless steel, or cast iron — phosphorus creates brittle iron phosphide at ferrous interfaces. Always use Safety-Silv 45 (BAg-5) or Safety-Silv 56 (BAg-7) for any application involving ferrous base metals.
An air-acetylene torch is preferred for copper tube sizes up to 1-1/8 in OD in HVACR work. Oxygen-acetylene is required for copper 1-3/8 in and larger, and for thick-walled fittings. Heat the fitting first, then sweep to the tube to achieve equal temperatures. Apply rod to the joint gap on the side opposite the flame to confirm the base metal is drawing the alloy by capillary action.
- What is the difference between Stay-Silv 15 flat rod and round rod?
- Same BCuP-5 chemistry. Flat (15620F5) melts more evenly and suits standard HVACR fittings; round (15520S) is preferred for production lines. Both are self-fluxing on copper.
- How much alloy per joint?
- Approx. 0.1–0.2 troy oz per 1/2 in fitting; 0.3–0.5 troy oz per 1-1/8 in fitting. A 5 lb tube (≈80 troy oz) covers 160–800 joints depending on size.
- Is Stay-Silv 15 safe for potable water lines?
- Yes — lead-free and cadmium-free. Verify local plumbing code requirements for brazing vs. soldering on specific water line types.
- What AWS classification is Stay-Silv 15?
- AWS A5.8 BCuP-5 / ASME SFA-5.8 BCuP-5. Also QQ-B-654A BCuP-5 and ISO 17672 CuP 284.
Browse the full brazing alloy collection. See also the Harris Stay-Silv 15 flat rod — 1 ea tube (15620F1) for smaller-quantity purchases, and the Harris Stay-Silv 15 brazing strip (15S0051) for pre-placed brazing applications. Specification reference: Harris Products Group and AWS A5.8.