Final answer:
Lead-free solder made of tin and copper is the most commonly used solder in plumbing to join copper pipes, adhering to safety regulations aiming to prevent lead poisoning.
Step-by-step explanation:
The most commonly used solder in plumbing, especially when dealing with copper pipes like those referenced in the plumbing of residential water mains, is a lead-free solder typically composed of a mixture of tin and copper. This type of solder has become especially prevalent since concerns over lead poisoning prompted regulations that ban the use of lead-based solders in drinking water systems. In the case where water pipes made of lead are replaced with copper pipes to prevent lead poisoning, as described in the exercise examples, the plumber would use this lead-free solder with a propane torch to safely join the copper pipes.
The most commonly used solder in plumbing is lead-free solder. This solder is made of a combination of tin and copper, and it is used to join copper pipes together in plumbing systems.
Lead-free solder is preferred in plumbing because it is safe for potable water systems. Lead solder, which was previously used in plumbing, has been phased out due to its potential health risks.
Lead-free solder has a lower melting point than copper pipes, allowing it to melt and form a strong bond when heated with a propane torch or soldering iron.