How to sweat a copper pipe – Sweating pipe

Sweating pipes is easier than you can think and it is a DIY(Do It Yourself) process. With the right tools and precision, sweating a copper pipe can be done in no time. It is not difficult but it takes practice.

Steps: Soldering Basics

    1. Cut the pipes: A clean cut makes all the difference. Use the correct cutting tool and lodge it tight around the pipe to get a clean and perfect cut. A tube cutter or a hack saw can be used, but tube cutter gives a cut with less burs.

    1. Clean the edges: Wipe off the cut edge to remove any burs. A wire brush would be the preferable tool to clean the bare metal inside the pipe. If you use a hack saw, a filing tool is required to remove the extra burs. The outside can be cleaned using a sand paper or a cleaning brush, until it attains a shiny surface.

    1. Assemble: The necessary fittings, pipes and joints are to be kept ready. Sweating the pipes one after another without any hesitation is easier as the heat flow will be even and quick.
    2. Flux/ soldering paste: Apply flux around the pipe evenly. This flux can help the smooth spread of solder. Not just the outside but also the insides are to be applied with flux.

    1. Heat: Do not apply heat directly on flux, the blue flames should just touch the pipe and not heat them too much. Apply heat on the pipe after joining the two ends. The best way to determine if the pipe is heated to the soldering temperature is to check by touching the solder on the join. If the solder melts and runs along the join, then it is at the right temperature.

    1. Sweat connection: The soldering is a capillary motion. Once two joints are in its place and the flux has spread evenly, Start sweating the copper fitting. Excess solder will run inside the pipe and clog the pipes. For vertical joins extra care is to be taken to not let the solder inside and be quick in running the solder around the joint.

    1. Clean: Let the solder rest for few seconds and then wipe them with a clean rag after applying some flux while the pipe is still warm. This is to make sure there is no excess solder and applying flux will make it easier to clean.

How to solder copper to brass – The sweat connection

Soldering is technique which involves a metal with lower melting to join a metal with higher melting point. Copper is often used with brass fittings and soldering them involves the use of some tools, they are:

  • Propane or Mapp gas torch
  • Heat shield- To prevent from getting burnt though handling with correct tools should do the trick.
  • A mirror (optional) – Required in intricate work where the other end can’t be seen from the work perspective.
  • Soldering wire- The solder material in wire.
  • Flux- Used to provide a firm solder between copper and brass and prevents the insides from oxidation. Oxidation prevents the solder from sticking to the brass and copper.
  • Cleaning brush How to clean copper pipe – To remove burs. Sand paper will work too, but cleaning brush will do a better work.

Soldering basics: How to solder copper fittings to make the sweat connection

  1. Measure the copper pipe and the brass fittings. None of the fittings should be large or too tight. Correct fit is the first step in getting a neat solder.
  2. Remove the burs using a 3/4 inch cleaning brush. A shiny look on the outside should do. The shinier the better.
  3. Apply the copper pipe ends with flux and even out the application with brush strokes.
  4. Take the brass fitting and screw them down onto the copper. The screwing motion is to let the flux stick to the insides of the brass fittings as well.
  5. Soldering copper pipe: Before soldering the joints are to be heated to a point where the metal glows. Light up the torch and start heating the metals. Move the torch in a way that will help the heat spread evenly. When heated too much the metal starts glowing in a red shade. This would mean you have to let the metal cool down a bit before you solder.
  6. Sweating pipes: Once the correct temperature is been attained, place the solder perpendicular to the joint. This is to let the solder flow into the joint. Touch the tip of the solder wire at the point where the joint is and keep moving it along the joints. The solder wire will melt itself. Follow the path with the torch to ensure it has stuck.
  7. Once all the gaps are filled in with the soldering wire let the metal cool down. When it is still warm wipe off with a wet rag to remove any excess solder running along.
  8. Congrats- You now know how to solder properly and how to solder copper pipe!

How to solder copper refrigerant tubing

Weld copper pipe

How to weld copper pipe? Well you don’t always have to! Soldering implies that copper is soldered with a metal having lower melting point and must be soldered with silver-based components. Refrigeration technicians have reported that a technique called soft soldering can be used to reduce costs. Sweating copper pipe.

Analysing that statement:

  • Soldered copper tubing is installed for refrigeration systems. Solders can be formed with many combinations, Tin/lead and Tin/antimony are not recommended, as they are of less strength. But Tin/silver is a preferable option in order to avoid welding copper pipe.
  • By cleaning, fluxing, and heating a copper plumbing joint we remove any oxidation. Nitrogen is not required to do this, which will reduce the cost in a large scale. The other advantage is that, there is no need to carry the cylinder around with you.
  • On using a Tin/silver to solder the copper pipe we get the advantage of handling a smaller torch with less heat can be used to weld. This implies less weight in carrying the equipment. Another advantage is, less heat means less damage and need to less cautious. The only disadvantage is that they are limited if service temperatures exceed this.
  • Servicing of the equipment is a pain to the user. It is better to follow the instructions and recommendations of the manufacturer. They tend to be conservative in what they recommend and that may be implying to use copper brazing over soldering.

Soldering basics for a sweat connection:

  • Measure the cuts and clean them. Apply flux and spread them but do not apply on the ends, rather rotate the fittings.
  • This action will allow the flux to spread on the inner surface of the fitting as well. The type of flux depends on the type of metal used.
  • Light the torch and move the torch. The movement of the torch is suggested strongly to avoid over heating of the parts. The heated parts will make it easier to melt the flux.
  • Move the flame away from the joint. When the temperature is correct to melt the solder, stop applying heat directly. You are now sweating copper pipe.
  • Continue copper soldering by touching the solder on the copper fitting plumbing joint section, until a ring is formed by the solder material. The silver solder will make joining the refrigerant copper tubing and components a much easier process.

How to solder copper pipe upside down

Sweating Copper pipe

              Soldering  copper pipe is usually done easily if proper techniques are known. It can be done by you easily by following the simple steps. Soldering is the process which has two or more items and usually it contains metal. The two items are to be joined with the melting and also the filter metal in the joint. Soldering is quite different from welding as it does not involve the melting of the work pieces. There are 3 simple steps in how to sweat copper pipe. The first step is to take some time and start with the small flame and it should be large enough to reach most of the place of the copper.


Sweating copper pipe

              Once the pipe heats up, torch the end of the solder plumbing  joint at about  90 degrees, from the flame source. keep the solder away from the melting point of the flame. The large sized pipes will require you to move the solder along the joint face. You should be able to withdraw the flame and then feed the solder in the hot plumbing joint on smaller pipes.

Let it cool down

              You should not wipe the joint until it cools down. You can see it if you watch that the solder goes from the silvery color to the bright color. In such case you should allow it to cool down, clean it and then try again. The dulling gets off once the soldering starts setting down. If the fitting shows too much of rainbows or turn blue then it means that you have used too much heat. Home repair projects are becoming very popular in the current times. People love their home and take interest in it and also feel the enjoyment and satisfaction in maintaining the home. Sweating copper pipe is an easy task which needs a procedure to be followed properly.

              If  followed, soldering upside down is no different than other positions because if you solder properly the solder sucks into the joint and follows the heat.

How to solder pipe upside down

The main concern is safety. Do not ever place yourself under the work. As you solder, both the hot flux and the hot solder will drip down and burn, main, or lose eyesight….its not worth it! Figure out how to position yourself in a way other than under the work, even if this means you have to dig, remove floorboards ect. This explains to the question how to solder copper pipe upside down. See the main page for more safety and skill tips.

What’s the difference between copper soldering, brazing and welding?

The basic concept is temperature.

Most good copper solders melt under 500 F degrees.

Brazing occurs over 840 degrees.

Welding occurs at around the melting point of copper, over 1900 degrees.

Sweating copper pipe










Soldering: The goal of sweating copper pipe is to heat the pipe/fitting enough to melt the solder but not so much as to anneal and soften the pipe….also over 800 degrees you can burn off all your flux. When the solder melts it seeps into the space between the copper pipe and the fitting cup creating a very strong joint. Strength of the silver solder is Tensile Strength – 5,000 PSI (at 250°), higher than the hard pipe (1250psi) and higher than the 95/5 solder (1000 psi). The solder must fill at over 70% of the void space between the pipe and fitting to meet piping code standards.  Silver solder ‘flows’ much better and should be used. The extra cost will be covered by not having failed fittings. It sucks having to take the system all apart just for one failed joint…so the extra cost of the solver solder pays for itself pretty quickly.


Figure 2 Brazing Copper Pipe

Brazing: usually occurs between soldering and the copper melting temperatures. An interesting thing happens when copper is brazed or welded. Copper anneals at around 700 degrees and loses strength when this happens…up to half its strength. So the act of brazing produces a system where the pipe is the weak point and the joints the strongest. However, this system is tougher and better fit for vibration like a mechanical system(refrigeration). That’s why most refrigeration systems are brazed. However, be sure to use the annealed copper charts when looking to meet the system strength requirements, not the hardened copper. Brazing has some conditions: there should be a fillet buildup as well as penetrating the brazing material into the pipe fitting Joint(minimum penetration is three times the heaver wall thickness)….vs a soldered joint does not need the fillet but the penetration is about 10x the wall thickness. Brazing is done with MAPP gas or oxygen/acetylene.

Welding Copper Pipe


Welding occurs at higher temperatures. For example most of the filler metals melt between 1100-1600 degrees depending on composition. Using rods containing silver yield great results. There is no penetration into the socket, the pipe and fitting are actually fused and heated together along with the filler metal. The oxygen/acetylene torch or welder create a copper puddle and then the rod is fed into it in a swirling pattern to mix the two parts. Copper is tricky though, heat it too much and it separates and beads like water on a waxed surface…poking a nice big hole in your work. Practice on scraps before welding copper pipes.

Brazing copper pipe – the mystery of Rosebud

Brazing copper pipe – the mystery of Rosebud.

What is Rosebud?

              For you movie fans, Rosebud is not a mythological childhood sled from a strange childhood! It’s a type of torch tip that looks like a rosebud, which is great for the kind of rapid broad heating that’s great for brazing copper.

Rosebud flame – brazing copper

Soldering is the process which has two items to be joined by melting  the filter metal in the joint. Soldering is quite different from welding copper pipe  as it does not involve the melting of the work pieces(welding copper pipe actually melts the metal pipe). Brazing is in between welding and soldering heat wise. You can easily learn to braze successfully at your home. The first tip for is that you need to use the proper flame for the project. The flame which is perfect for the brazing copper pipe is known as the rosebud flame. Be sure to use a  carburizing or neutral flame.

Brazing copper pipe



There are 3 simple steps. The first step is to take some time and start with the small flame and it should be large enough to reach most of the place of the copper. Once the pipe heats up, touch the end of the silver brazing alloy to joint at almost 90 degrees, from the flame source. It allows keeping the alloy away from the melting point of the flame. If you have done this process properly then the braze will go around the joint and it will meet the other part of the joint where the flame was. You need to follow the plumbing joint all around with the brazing wire because at the end of the project there should be a fillet weld at the joint. The large sized pipes will require you to move the braze along the joint face.


              Heat the pipe not the silver-brazing wire ! Use flux ! It is always preferable to under heat rather than overheat. Once you have ringed the joint, move the heat from the fitting. Start at the bottom, then the sides should go fast and they should receive heat from the initial work. You should not wipe the joint until it cools down. You can see it if you watch that the braze goes from the silvery color to the dull color. The dulling gets off once it starts cooling down. If the fitting shows too much of rainbows or turn blue then it means that you have used too much of heat.

              If you are new and have any doubts then you should develop some skills on extra copper scrap. Try it on your own with ease.

See the main page for more detail. Follow the same safety tips, cleaning, sanding, and fluxing techniques on the main page  for sweating copper pipe as for brazing.

How to weld copper – oxygen-acetylene

Welding Copper Pipe: Oxygen / Acetylene

Safety: Arrange working conditions per OSHA standard practice and rear the proper  protective gear: Long leather gloves without holes, Safety glasses, welding helmet with auto darkening, welding pants and jacket, solid leather boots, respirator, welding table, a bucket of water, and a certified fire extinguisher. All flammables from your non-flammable working surface must be removed. Remove everything except what you need for welding. The welding helmet, shields your skin and eye(careful here) from any sparks; also,  protects against  damaging ultraviolet rays that can burn  your vision. Note: exposed skin will result in a very bad sunburn, so take care. Fully ventilate the area or work outside. Only have the gas welder on ONLY when welding. Tempting:  leave it lit for a moment while you quickly grab something, but, don’t put a lit torch down!  Keep cylinders away from the welding area and fasten in your cart.

Auto Darkening for copper welding

Figure 1 Auto-darkening helmet: welding copper pipe. Don’t fool around, only use the auto-darkening type, your eyes are worth it.

Only weld clean shiny copper. Remove all contaminants….The weld will turn crappy if everything is not newly shiny(wipe condensation from sweating copper pipes, dirt, with isopropyl alcohol, then,  wipe with a dry, clean,  rag).

Use a grinder, emery cloth, wire brushes, to eliminate copper oxide and make everything new looking(shiny). Clamp work securely.

Picking materials: Try to use oxygen-free copper because it  gives off less hazardous fumes.

Picking your welding equipment: Most welders prefer old school: the oxy/acetylene torch set up. Copper is very heat conducive; heat rapidly spreads across the piece. Torch installs enough heat to easily preheat, conversely, a welding machine applies heat into a very small surface area. So, lets talk about oxy  welding.

Welding Copper pipe

Figure 2 Welded copper pipe

Gas equipment set up: Select your head. Use a number 2 or 3, not a cutting head. Be sure to clean the tip free from contaminants before starting. Turn off all valves, both at the torch and the gas cylinders. Slowly turn on the acetylene about a half turn. Pressure should be around 6 psi. Then quickly turn on the oxygen to about 9 psi and light. Did we talk about how important ventilation is ?  The flame will be smoky orange now…increase the oxygen until you get a white and blue flame, the white should be about .4 inches long. Don’t turn on the oxygen too quickly or you’ll flood out the flame. Better to start with a smaller flame and work slowly when beginning.


Test out on scrap metal the same thickness before trying on your final product.

Figure 3 How to weld copper pipe

Start your puddle:. Feed your LEAD FREE silver copper alloy rod into the puddle, again with a small semi-circular motion, then quickly advance the gas tip and rod until complete. Finished result should appear:  a stack of dimes laid aside. The conclusion result is that the two pieces you are welding, and the filler metal all mixes together. Practice with horizontal scrap before attempting vertical joints. The vertical puddle can drip away easily and requires good timing. Always let the copper air cool(not fan assisted) to avoid cracks.

How to Weld Copper Pipe

Figure 4 Welding looks like stack of dimes

Here’s interesting melting point information below. Very hot!

METALs                  Melting points(F)

Copper 1983
Silver, Sterling 1640

How to weld copper with a machine will be in another article. Sweating copper pipe is on the home page.


Sweating copper pipes – cure condensation

Sweating copper pipes are the silent killer to your house. Over time the moisture condensing on the cool copper pipe can cause damage in many ways. The condensate can dampen wood and cause structural failure, termites, wood rot, as well as insect and rodent water supply, and finally, even black mold. It can also lead to increased pipe corrosion. Is not easy to get rid of this condensation especially in warmer humid climates.

The warm air hits the cool pipe and the water condenses on the pipes just like a glass of ice water on a summer day. The dew point in the basement must become lower or the basement, must become drier, or the water pipe, warmer.

How to remedy sweating copper pipes?

There are three techniques: insulation, mixing valves, and containment.
The use of foam pipe insulation that is well wrapped will keep the moist air away from the pipe, preventing over or reducing condensation. The method is to wrap the pipe from house entry, throughout the house, including under the sink or toilet. Also in extreme cases and examples the toilet tank itself may need to be wrapped in insulation. There are actually premade toilet tank insulation kits which use Styrofoam of the inside of the tank to warm the temperature of the outside of the tank. Be sure to seal all joints to prevent infiltration.

Figure 2 Insulate to reduce sweating pipes
Mixing valve. Another method to prevent sweating copper pipes is to route a hot water pipe and mix it into the cold water. The hot water tees into the cold water and the mixing valve mixes the two temperatures to produce warm water. The warm water being warmer than the moist air prevents condensation. The mixing valve is adjustable and enables the fine-tuning of the temperature . Optimally, the mixing valve will be adjusted during the four seasons to minimize condensation and minimize the use of warm water. The mixing valve should be installed for the whole house close to the point of pipe entry into the house. Most houses use three-quarter inch incoming water supplies, therefore the mixing valve would have to also be three-quarter inch on all three legs: the two inlets and warm outlet.

How to solder copper pipe

Copper pipes play the key role in the supply of water, both hot and cold, and as a refrigerant line in the HVAC systems. Sweating copper pipe is joining two plumbing joints using a filer metal, either the same as that of the pipe or some other, which has a lower melting point. This forms a permanent connection.

How to solder pipe:

It is a simple process that could be done at home. The complexity level for soldering a copper pipe is simple. To obtain a perfect solder, selection and usage of the materials used are important.

Torch– Flames and their force determines the perfection of soldering a copper pipe. The flame shapes are different, for instance take the cone shaped flame, it concentrates on one particular spot whereas the rose bud shaped flame will wrap the pipe and will even out the temperature. Self-lighting/Auto start torches are safer and easier to use. Normal torches would require lighting and relighting often involving extra worry about burning down yourself or the place.

Cleaning brush– A clean pipe will have a neat finishing. Make sure you clean the ends of the pipe with any abrasive material. This is to make the soldering strong.

Flux– Before soldering apply the flux on the ends of the pipes. Flux helps in even spreading of the solder into the joints.

How to solder properly:


  1. Assemble all the pipes and copper fittings to be joined. Meddling with pipes after lighting a torch is dangerous and would result in unclean soldering.
  2. Flux the joints evenly. Right amount of flux would do the job itself.
  3. Light the torch and heat the plumbing joints evenly.
  4. Soldering Copper: Place the solder 90 degrees to the plumbing joint and rotate the joint slightly to let the solder spread. With the right amount of flux and heat the solder will flow and fill the gaps.

Things to be careful about: How to sweat copper pipe


Heat level: Over heat would burn the ends and leave a black burnt mark on the pipes. Under heating would not let the solder flow evenly rather making them get logged evenly.

Application of flux: Spread it with smooth motion. Do not dab.

Torch level: Make sure the flames are about 1-2 inches. This is easier to hold at a position to apply proper heat.

Move to next joint: As soon as you finish one joint move along to the next joint. The heat from previous would help in making the work easier if the joint is a subsequent one. This is how to solder pipe.

Touch: Touch the flame to the copper pipe every second to get a better flow.

How to solder copper pipe in China

Copper pipes are more usually utilized in plumbing then most other alloys due to they are very less likely to corrode. Well you can know how to sweat copper pipe in China successfully. In this information about soldering a copper pipe you may find why you might have failed prior, and how to accomplish.

The method of soldering copper in China is a little scary.

On Saturday, September 26, 2015, 13:49, The reported the following ”Soldering materials which connect pipes were officially confirmed to be the main reason for excessive lead in the drinking water of 11 public housing estates for the first time.”

In fact the lead levels in the water where 585 times the allowable levels when compared to Britain. Hmm, next time in China I guess I’ll drink the bottled water, right !

Now we know not to use lead solder!!! Use tin silver solder instead.  Lets get to the sweating pipes and soldering copper pipes.

The right flame  – How to solder pipe

The initial tip is to utilizing the proper blaze for the task. The blaze which is right to solder copper pipe joints is the “rosebud” blaze. A cone structured blaze puts lot of heat at one spot it reaches. A rosebud blaze wraps the pipe in flame, bringing the whole joint to the proper temperature at the same period.

You are attempting to apply solder to a point where a pipe enters the fitting, to enable the solder run into a joint by capillary action. To make this you need an even temperature across the whole joint. Your rosebud blaze will free you to put the solder at correct moment rather than forcing you to have that blaze moving which plays devastation with your timing.

Copper soldering basics – How to solder copper fittings.

How to solder copper pipe in China in three easy steps without lead(!!!):

  1. Begin with a little blaze, just large sufficient to go most of the manner across the pipe.
  2. As the pipe gets heat up, touch the corner of a solder to the joint at 90 degrees from source of the blaze. That maintains the solder from melting off in blaze.
  3. Touch it there each second or so till it moves into the sweat connection joint.

If you’ve made this right the solder will go across the joint and meet at other end mostly by itself. For bigger pipe sizes you might need to move a tip of a solder along a joint face. You might be able to extract the blaze and feed solder to yet hot joint. It’s always good to underneath-heat than to over-heat when soldering.

As early as you’ve ringed a joint with the solder, then shift to the next corner of fitting. Subsequent sides must go quicker having already attained heat from the first work. Don’t wipe a joint or jiggle it in any manner till it gets set. You’ll notice if you see which the solder goes from very silvery to just vivid. As early as this dulling happens the solder has set.

If a fitting glows and turns to “rainbows”, you’ve utilized too much heat. Allow it to cool, cleanse it up inner and outer and try again.

I hope the aforesaid soldering tips have helped. Joining copper pipe by soldering water pipe isn’t actually really complex once you have the hang of it.