A plumber is troubleshooting a persistent drip leak at a newly formed 1-1/4 inch (32 mm) copper soldered joint in a domestic water supply line. Upon inspection, it's observed that the solder did not fully flow around the entire circumference of the joint. Which of the following is the most probable cause for this incomplete solder flow?

Question: A plumber is troubleshooting a persistent drip leak at a newly formed 1-1/4 inch (32 mm) copper soldered joint in a domestic water supply line. Upon inspection, it's observed that the solder did not fully flow around the entire circumference of the joint. Which of the following is the most probable cause for this incomplete solder flow?

Answer options: ✅ Insufficient heating of the fitting or pipe during soldering.

• Excessive application of flux causing blockages.
• The use of lead-free solder instead of lead-based solder.
• The pipe and fitting were not perfectly concentric.

Correct answer: Insufficient heating of the fitting or pipe during soldering.

Explanation: Incomplete solder flow, often indicated by dry spots or drips, is most commonly caused by insufficient or uneven heating of the joint components (pipe and fitting). The solder will follow the heat, and if one part is cooler, the solder will not draw into that area. While excessive flux can cause issues, and lead-free solder flows differently, insufficient heat is the primary culprit for incomplete flow.