How to sweat copper pipe
If you want to repair, add-on to or create a water system using copper pipe, it will be of great benefit for you to learn how to sweat copper pipe. To sweat copper pipe means to solder fittings or fixtures directly onto copper pipe. When you sweat copper pipe to fittings or fixtures, the joints are solid, leaf proof and will last virtually forever.
To sweat copper pipe to copper fittings is not really very difficult at all. It is slightly harder to sweat copper pipe to bronze fittings, but this is done much less often than sweating copper fittings. Bronze fittings are usually on the inlets of fixtures such as spigots and drains.
If you are new to sweating copper pipes, it's good to know that you can plumb an entire water system in a new house and never be required to sweat a bronze fitting to copper pipe. Simply use fixtures designed with threads, and sweat threaded copper fittings onto the copper pipes.
To sweat copper pipe, here are the things you'll need:
1) Flux – be sure it's safe for drinking water use.
2) Solder – be sure it's safe for drinking water use.
3) Some 220-grit emery cloth.
4) A flux brush.
5) A dry rag.
6) A rag and a small pan or bucket of fresh water.
7) A small, hand held, self igniting torch. This can be butane, propane or MAPP gas. A propane torch is highly recommended for beginners and the occasional do-it-yourselfer. These propane torches can be purchased at hardware stores for anywhere from $10 - $200.
Other items you will likely want to have on hand for your project(s) are: a small pipe cutter • a fine metal file • a measuring tape • a fine point marker • a small fire extinguisher – especially if you are going to sweat existing copper pipes in a wall or ceiling.
The most common copper pipe fittings that you'll use when you sweat copper pipes are: 90° elbows; 'T's; connectors and caps. Copper pipe comes in both rigid and flexible. Using flexible will allow you to easily bend pipe around many angles. Flexible copper pipe is also much more forgiving for the novice plumber as small adjustments can be made to ensure a perfect final fit. You sweat copper pipe the same way, regardless of whether or not it is rigid or flexible.
Let the sweating begin…
Step 1 – If you are working on an existing water pipe, you must first completely drain all water from the line. If there is any water at all in the line you won't be able to sweat the copper pipe. Shut off the water main and open all faucets and leave them open. Allow the lines time to dry inside before starting.
Step 2 – Prepare the copper pipe and the fitting for sweating by wiping off any dirt with your dry rag. Then use your emery cloth to lightly sand the end of the pipe and the inside of the fitting where the pipe will go.
Step 3 – Use the flux brush to apply flux to the end of the copper pipe and the inside of the fitting. Be generous – you can't use too much, but you do not want to miss any spots.
Step 4 – install the copper fitting onto the copper pipe. Make sure it is completely seated. Twist and push as necessary. Make sure the copper fitting is properly aligned for use – this is especially important with 90° elbows.
Step 5 – Take your water line safe solder and unroll 8" – 10". Leave the solder attached to the roll and stick the piece you'll be using straight out. This will make it easier to use and also keep your hands away from the heat of the torch.
Step 6 – It is recommended at this point that you put on your safety equipment: gloves and eye protection.
Step 7 – Fire up your torch and start to heat the copper fitting and copper pipe at the joint area. Always start on the fitting as it will require more heat to get to the proper temperature. Keep the flame about 2" – 4" away from the copper. Constantly move the torch flame – remembering to move around and down the fitting and copper pipe to about ½" from the joint.
Step 8 – After a few seconds, remove the torch flame from the joint and touch the end of the solder to the joint where the copper pipe goes inside the copper fitting. If the solder does not melt into the joint, continue to heat it. Repeat this process until the solder melts and disappears into the joint. Capillary action, the flux and the heat will pull the solder inside the joint, even if it's upside down. When a droplet of solder forms outside the joint, pull the solder away.
Step 9 – Take one of your rags and get it wet in your fresh water. Leave it pretty wet, but not dripping. You do NOT want to cool your work too quickly as this will make the copper brittle. Start about 8" away from the joint on the copper pipe and wipe it with the wet rag. Slowly move towards the joint until you hear a 'sizzle.' When the sizzle stops, move closer to the new joint. Continue this process until you are finally on the joint. Now wipe it clean.
Step 10 – turn your water system back on and then start closing the faucets. Close faucets from the lowest to the highest to help remove trapped air from the lines.
Some other tips
• Practice how to sweat copper pipe on some scrap copper pipe with a few fittings before you start working on your final projects. You'll get the hang of it quickly, and you can reuse the fittings for your practice – just heat them until the solder is liquid and slide them off with a pliers.
• Never try to cut copper pipe with a hacksaw. This will create heat and ruin the perfectly round end of the pipe. Use a small pipe cutter.
• If you are going to sweat copper pipes often, it is definitely worth spending a few dollars and buying a tool that is designed for cleaning the inside and outside of copper pipes and fittings.
• If you want to sweat copper pipe to a bronze fitting end, be sure to focus on heating the bronze much more than the copper pipe. It will be thicker and require more heat. If you sweat copper pipe to a bronze spigot fitting, be sure to fully open the spigot before you start to heat the bronze.
• After you sweat the copper pipes in a water system, be sure to flush the system out by running the water for several minutes before you start to use it again. This will remove any remnant flux or debris.