In residential applications, threaded steel piping is predominantly used for which system?

• A. Water supply lines
• B. Refrigeration lines
• C. Gas lines
• D. Drainage lines

Answer: (C)

Threaded steel piping is favored for gas lines in homes because it provides a strong, leak-tight, and rigid network with joints that can be securely threaded and sealed. This durability is crucial for natural gas and propane, where even small leaks are dangerous, so the reliable joints formed by threaded steel pipe are highly valued. In residential work, other systems use different materials for practical reasons: water supply lines typically use copper, CPVC, or PEX for their corrosion resistance, flexibility, and ease of installation; drainage lines rely on cast iron, ABS, or PVC for waste, which are lighter and easier to install in large-diameter pipes; refrigeration lines use copper or aluminum tubing with fittings suited to refrigerants rather than threaded steel. So, the system that predominantly uses threaded steel piping is gas lines.