If you’ve tried to solder copper pipes and failed, you may be hesitant to try again. Before you give up, however, consider giving it another go. Failure in soldering copper pipes usually stems from using the wrong tools and improper techniques. Soldering is not really that difficult once you know the basics.
Proper flame use is the most important thing to consider in the task. The flame needed to sweat copper pipe joints is called a rosebud flame. A rosebud flame uses a lot of oxygen and acetylene gas flow to keep it cool and prevent it from popping back. A rosebud flame will wrap the pipe with its flame, heating the whole joint at the same time.
When soldering copper pipe joints, keep the nearby soldered joints from melting. You can prevent this by wrapping a wet rag around them. You will be heating only the area that you want to solder and not the adjacent soldered areas of the pipe.
Here are the proper steps for soldering:
- Start slowly using only a small flame (just large enough to reach most of the way around the pipe)
- As the pipe begins to heat up, touch the end of the solder to the joint about 90 degrees from the flame’s source. This will keep the solder from melting off in the flame.
- Touch the flame to the joint every second until you have covered the entire joint.
If you follow the steps correctly, you will be able to solder around the joint. If you are soldering a larger-sized pipe, you will need to move the tip of the solder along the face of the joint. You can put the flame away and feed the joint with solder while it is still hot. Remember that it is safer to under-heat your pipe than to over-heat it.
After you have soldered the joint, you can proceed to the next side of the fitting. Soldering the other side will be faster than the first one because the pipe has already been heated. Do not wipe or move the joint until you are sure that the solder has set. You will observe that the solder will turn from plain silver to bright. Once the dulling has completed, the solder has set.
If you notice that the fitting glows, turning blue or rainbow-colored, your soldering has failed. This indicates that you have used too much heat. Simply let it cool down, clean up the inside, and try again.