How do you choose the right solder for different types of pipes and fittings?

2 What are the main types of solder?

There are many types of solder, but they can be broadly classified into two categories: soft solder and hard solder. Soft solder has a low melting point (below 450°C) and is usually made of tin and lead, or tin and other metals like copper, silver, or antimony. Hard solder has a high melting point (above 450°C) and is usually made of copper and zinc, or silver and other metals like cadmium, nickel, or phosphorus.

3 How to choose solder for copper pipes and fittings?

Copper pipes and fittings are widely used in plumbing, heating, and cooling systems. They are easy to solder, but you need to use the right solder for the job. For water supply lines, you should use lead-free solder, which is safer and complies with most building codes. Lead-free solder is usually a tin-copper or tin-silver alloy, and it has a higher melting point than leaded solder, so you need a hotter flame to melt it. For drain, waste, and vent lines, you can use leaded solder, which is a tin-lead alloy, and it has a lower melting point and better flow than lead-free solder. For both types of solder, you also need to use a flux, which is a paste that cleans the metal surfaces and helps the solder stick.

4 How to choose solder for steel pipes and fittings?

Steel pipes and fittings are often used in gas, oil, and steam systems. They are harder to solder than copper pipes and fittings, because steel has a higher melting point and is more prone to oxidation. To solder steel pipes and fittings, you need to use hard solder, which is a copper-zinc or silver-based alloy, and it has a high melting point and strength. You also need to use a flux that is compatible with steel and can prevent rusting. Hard soldering is also called brazing, and it requires a torch that can produce a very hot flame.

5 How to choose solder for other types of pipes and fittings?

Besides copper and steel, there are other types of pipes and fittings that you may encounter in industrial maintenance, such as brass, bronze, cast iron, or plastic. Each of these materials has its own characteristics and limitations when it comes to soldering. For example, brass and bronze can be soldered with soft or hard solder, depending on the application and the temperature range. Cast iron can be soldered with hard solder, but it requires special preparation and care to avoid cracking. Plastic can be soldered with special plastic solder, but it may not be as strong or reliable as metal soldering.

6 What are some best practices for soldering pipes and fittings?

No matter what type of pipes and fittings you are soldering, there are some general tips that can help you achieve a good result. To begin, clean the metal surfaces with a wire brush or sandpaper to remove dirt, grease, or oxidation. Next, apply flux evenly to the metal surfaces and the inside of the fitting. Cut the solder into small pieces and bend them into a U-shape. Then, heat the pipe or fitting evenly with a torch until the flux bubbles; touch the solder to the joint and let it melt and flow into the gap. After that, remove the heat and let the solder cool and harden; wipe off any excess flux or solder with a damp cloth. Finally, check the joint for leaks and cracks.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?