Brazing HVAC tubing involves heating base metals to what range?

Brazing HVAC tubing involves heating base metals to what range?

• A. Above melting point
• B. Above 700°F but below the metals' melting points
• C. Below 0°F
• D. At the exact melting point

Answer: (B)

Brazing works by melting a filler alloy and letting it flow into the joint while the base metals stay solid. To achieve that, you heat the assembly high enough to melt the filler but well below the melting points of the base metals. In HVAC practice, that means raising the temperature to above about 700°F, yet keeping it below the metals’ melting temperatures. This range lets the molten filler flow into tight gaps by capillary action and form a strong joint without actually melting the tubing or fittings. If you go above the base metal melting point, the base metals could weaken or deform; if you stay below the filler’s melting point, the filler won’t flow to form the joint; and heating exactly at the melting point makes control very difficult.

Brazing works by melting a filler alloy and letting it flow into the joint while the base metals stay solid. To achieve that, you heat the assembly high enough to melt the filler but well below the melting points of the base metals. In HVAC practice, that means raising the temperature to above about 700°F, yet keeping it below the metals’ melting temperatures. This range lets the molten filler flow into tight gaps by capillary action and form a strong joint without actually melting the tubing or fittings. If you go above the base metal melting point, the base metals could weaken or deform; if you stay below the filler’s melting point, the filler won’t flow to form the joint; and heating exactly at the melting point makes control very difficult.