Red Seal Steamfitter/Pipefitter Practice Exam

Which process is used to create a strong seal between two copper fittings?

1. Welding

2. Soldering

3. Brazing

4. Gluing

The correct answer is: Soldering

Soldering is the correct process used to create a strong seal between two copper fittings due to its ability to join metals using a filler metal that has a melting point below that of the base metals. In soldering, a soldering alloy—typically a combination of tin and lead or other metals—is heated until it melts and is applied to the joint between the two copper fittings. Upon cooling, the solder solidifies, forming a strong bond that is capable of withstanding pressure and resisting leaks. This method is particularly effective for copper plumbing because it allows for reliable, watertight connections without the need for high-temperature equipment, differentiating it from welding, which involves melting the base material itself and requires more specialized skills and equipment. Brazing, while similar to soldering, involves higher temperatures and uses a different filler metal, and is often used for metals other than copper or in applications requiring even higher strength. Gluing, on the other hand, is not a common method for joining metal fittings in plumbing applications, as it is typically used for non-metal materials and does not provide the strength and durability needed in a plumbing system.