What material is recommended for the joint between gas lines and brass fittings?

The recommended material for the joint between gas lines and brass fittings is 15% silver solder. This choice is correct because silver solder provides a strong and durable bond that can withstand the high pressures and temperatures that gas systems typically encounter. The use of silver solder ensures that the joint is not only gas-tight but also resistant to corrosion, making it ideal for long-term applications in gas lines.

In contrast, while materials like Teflon tape and pipe dope are often used in various plumbing applications for sealing threaded joints, they may not be suitable for gas applications under certain conditions. Teflon tape can sometimes break down in the presence of specific gases and may not always provide the necessary strength for metal-to-metal joints. Pipe dope, although often used for sealing joints, might not form a sufficiently strong connection for gas lines, particularly with brass fittings.

Plastic adhesive is never recommended for gas fittings, as it lacks the strength and durability required for high-pressure gas applications. Overall, the use of 15% silver solder provides the necessary properties for a safe and reliable gas line connection with brass fittings.