What type of joint is required to connect copper tube in standpipe systems?

• A. Soldered joint
• B. Brazed joint
• C. Welded joint
• D. Compression joint

Answer: (B)

Connecting copper tube in standpipe systems must be done with brazed joints. Brazing uses a filler metal fused at a temperature higher than solder but lower than the copper itself, and it flows into the joint by capillary action to form a solid, leak-tight bond. This creates a strong connection that can reliably withstand the hydrostatic pressures and testing demands of standpipe operation. Soldered joints use a lower-melting-point alloy and are not rated for the same pressure and long-term reliability required in standpipes, so they can creep or leak under service conditions. Welding copper, while possible in some trades, is not the standard method for thin-walled copper tubing in standpipes because it can cause distortion or weaknesses and isn’t as consistently reliable for these systems. Compression joints also don’t provide the same level of leak-tight reliability under high flow and vibration conditions typical of standpipe use. Brazed joints therefore meet the performance and reliability needs of copper standpipe piping.