Can you solder a pipe with water in it?

Soldering pipes with water in them can be challenging, but it is possible in some cases. The key factors to consider are safely draining as much water as possible, using the right soldering techniques, and taking precautions to avoid steam explosions.

Quick Answers

Here are quick answers to some common questions about soldering pipes with water:

• Is it possible to solder a pipe with water in it? Yes, it is possible in some cases if proper precautions are taken.
• Should you try to drain the pipe as much as possible first? Yes, draining as much water as possible first is highly recommended for safety.
• What soldering techniques work best? Lead-free solder and a hydronic soldering machine designed for wet pipes work best.
• What risks are there? Risks include steam explosions, being burned by hot solder or steam, and leaks if the joint is not soldered properly.
• What safety gear should be used? Safety glasses, heat-resistant gloves, long sleeves/pants, and possibly a face shield.

Draining the Pipe First

Before attempting to solder a pipe with water in it, the first and most important step is to drain out as much of the water as possible. Water conducts heat quickly and having any significant amount of water in the pipe can lead to dangerous steam explosions when applying hot solder.

Here are some tips for draining a pipe before soldering:

• Shut off the main water supply valve leading to the pipe section you need to solder. This may require shutting off the main house valve.
• Open the lowest faucet on the pipe system and let the water drain out as much as possible.
• Open any other faucets or drains at higher points in the system to allow air in and improve drainage.
• Consider using a wet/dry shop vacuum to suck standing water out of the lowest ends of the pipes.
• Allow time for the pipe to fully drain. Pipes may continue slowly dripping water even after 20-30 minutes of drainage time.
• Check if any isolated pipe sections still contain water. Drain these sections as much as possible by disconnecting at joints.

While it may seem tedious, taking the time to fully drain pipes before soldering greatly improves safety and the odds of completing a successful repair.

Using the Right Soldering Techniques

Careful soldering technique is important when working on pipes that still contain some residual water after draining.

Here are some soldering techniques to follow:

• Use lead-free solder. Lead solder has a lower melting point which increases steam explosion risk.
• Apply solder quickly to minimize heat. prolonged heat will produce excessive steam.
• Use a hydronic soldering machine designed for damp pipes. These machines heat and cool quickly.
• Heat the joint with a torch briefly before applying solder to vaporize water. This prevents the solder from splattering.
• Apply solder to the upper sides of the pipe joint first, followed by the bottom. This pushes steam and moisture downward and out.
• Wrap a wet rag around the pipe below the joint to catch any hot solder drips and quench steam.

Following these specialized soldering methods will give the best results when working on pipes that still hold some residual water after draining. Attempting to solder wet pipes with standard lead solder and a propane torch is extremely dangerous and should never be attempted.

Safety Precautions

Proper safety precautions are crucial when soldering any pipes with moisture still present. At a minimum, the following gear should be used:

• Safety glasses or goggles to protect eyes.
• Heat resistant gloves to protect hands and wrists.
• Long sleeve shirt and pants to prevent steam or solder burns on arms and legs.
• Possibly a face shield if working in a cramped space.

It is also wise to do the following:

• Clear any flammable materials away from the work area.
• Keep a fire extinguisher handy.
• Lay down drop cloths or tarps to catch drips and protect floors.
• Turn off power/gas to water heater if soldering pipes on the heater.

Never touch pipe sections being soldered without proper hand protection as they can quickly reach upwards of 300°F. Also be cautious of steam as it can cause severe skin burns.

Can PEX, CPVC, or SharkBite Fittings Be Used?

Some ask if it is possible to use alternate pipe joining methods like PEX, CPVC, or SharkBite fittings when a pipe contains water that cannot be fully drained.

The short answer is no. These types of fittings rely on being perfectly clean and dry. Any moisture present will likely cause leaks or failure of the connections.

Here is some more detail on each option:

PEX

PEX piping uses special crimp or expansion fittings. These fittings form a totally watertight seal when snapped or compressed onto the outer PEX tubing.

However, any moisture or water droplets on the inside or outside of the PEX would likely interfere with the tight seal and lead to leaks. PEX is really only an option for making initial connections on fully drained and dried pipes.

CPVC

CPVC also uses special solvent glues to permanently bond joints. CPVC glue relies on creating a chemical melt bond between the surfaces of the CPVC pipe and fittings.

Water or moisture prevent the necessary chemical reaction from taking place so CPVC glue joints will fail. Full drainage and drying is required first.

SharkBite

SharkBite push-fit fittings use an internal rubber gasket seal pressed tightly against the pipe. Trapped moisture or water drops could interfere with the gasket forming a tight seal.

Overall, SharkBites are not a reliable option on pipes that have not been fully drained prior. They are much better suited to dry initial installations.

Can Other Pipe Joining Methods Be Used?

While PEX, CPVC, and SharkBite fittings will not work, there are some other alternative pipe joining methods that can work on partially drained pipes:

• Compression fittings – Can form decent seals even with some moisture present on the pipes. Ensure pipe ends are cleanly cut and deburred.
• Flared fittings – Similar to compression fittings, flared fittings can seal adequately with some moisture present. Take care to properly shape the flare.
• Brazed joints – Copper and steel pipes can be brazed while slightly wet. Use extra flux and ensure the pipe is hot enough to vaporize moisture.

However, these options still carry increased risk over properly soldering a fully drained pipe. Soldering remains the preferred method whenever pipes can be fully drained in advance.

Step-By-Step Process for Soldering a Wet Pipe

Once the pipe is drained as much as possible, follow these steps to solder a pipe joint that still contains some residual water:

1. Assemble materials – lead-free solder, flux paste, hydronic soldering machine, propane torch, sandpaper, rags, safety gear.
2. Protect surroundings – clear area of flammables, cover walls/floors, place fire extinguisher nearby.
3. Prepare and clean all joint surfaces – sand and wipe off any dirt, oils, or grime.
4. Apply flux paste thoroughly to joint surfaces – this helps the solder spread and seals any small moisture pockets.
5. Wrap a wet rag around pipe below the joint – this will catch any drips and quench steam produced.
6. Heat joint briefly with propane torch – enough to vaporize any droplets and steam them away.
7. With hydronic soldering machine, apply solder to top of pipe first – it will flow downward pushing out steam.
8. Quickly finish applying solder around all sides of the joint to fully seal – aim for 3-4 seconds max.
9. Allow joint to fully cool before removing rag and handling – can take 1-2 minutes to solidify.
10. Carefully inspect final joint – reheat and add more solder if any gaps or holes are present.

Be sure to work quickly when applying solder to minimize heat exposure that can produce dangerous steam explosions. Following these safe soldering practices will allow for successfully joining pipes that could not be fully drained beforehand.

Potential Issues When Soldering Wet Pipes

Even when following all proper precautions, there are still some potential issues that can occur when soldering pipes with moisture still present:

• Steam explosions – Rapid production of steam can cause solder to splatter and risks scalding injuries.
• Blocked flow – Pockets of steam can form that block the flow of solder into the joint.
• Leakage – Any gaps not fully sealed by the solder will lead to leaks once water supply is restored.
• Cracks – Excess steam pressure may crack weak or corroded pipe sections.
• Burn-through – Prolonged heat exposure can burn holes in the pipe wall.

To minimize these risks, drain pipes as thoroughly as possible, use a hydronic soldering machine, work quickly, and take all advised safety precautions. Also thoroughly check joints afterwards for any signs of leakage, gaps, or cracks that may need re-soldering.

When to Call a Professional

In many cases, the best option is to have a professional plumber handle any pipe soldering jobs when significant water is present in the pipes.

It is recommended to call a professional plumber if:

• The pipes contain a major amount of standing water that cannot be drained.
• The affected pipes are in very tight, enclosed spaces.
• The pipes cannot be fully shut off from the water supply.
• You do not have the proper soldering tools and safety gear.
• The pipes show signs of serious corrosion or weakness.

Plumbers have specialized tools like vacuum pumps that can quickly drain pipes. They also have professional grade soldering equipment better suited for the task. If in any doubt about how to safely proceed, calling a plumber is the wise choice.

Conclusion

Soldering pipes with water still in them can be done with the right precautions and technique. However, it carries risks of steam explosions and potential injuries or leaks. The process also requires specialized soldering equipment to be done safely.

Whenever possible, fully draining pipes using faucets, valves, vacuums, and time is strongly advised before attempting to solder. Copper and metal pipes with lead-free solder can be carefully soldered when some residual moisture is still present if proper procedures are meticulously followed.

However, PEX, CPVC, and push-fit fittings should never be used as they require perfectly dry surfaces to seal correctly. Calling a professional plumber is recommended if pipes can’t be fully drained or if you lack the proper soldering tools and experience.

With careful drainage, planning, and execution, it is possible for a knowledgeable DIYer to solder a damp pipe joint. But when unsure, getting professional assistance is always the most prudent option to avoid potential water damage or injury.