How To Connect Pex To Galvanized Pipe

Preparing for the Transition

Connecting PEX (cross-linked polyethylene) to galvanized steel pipe requires careful planning and the correct materials. This involves considering potential corrosion issues, ensuring proper sealing, and adhering to plumbing codes. Ignoring these factors can lead to leaks, reduced water pressure, and potentially costly repairs.

Identifying Pipe Sizes and Compatibility

Prior to any connection, accurately determine the size of both the PEX and galvanized pipes. Galvanized pipe is typically measured by its nominal size, which is an approximation of the inner diameter. PEX, conversely, is measured by its outer diameter. These measurements are crucial for selecting the correct fittings. Using mismatched sizes will compromise the integrity of the connection.

The most common sizes encountered are ½-inch and ¾-inch. Measure the outer diameter of the PEX. For galvanized pipe, if possible, use a pipe measuring tool or refer to markings etched on the pipe. If markings are absent, measure the circumference and calculate the diameter. Consult a pipe size chart to determine the nominal size.

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Gathering Necessary Materials

The materials needed for this project are crucial for a secure and leak-proof connection. You will require:

PEX tubing
Galvanized to PEX fitting (transition fitting)
Pipe wrenches (two)
PEX cutter
Measuring tape
Deburring tool (for PEX)
Thread sealant (pipe dope or Teflon tape)
Safety glasses
Gloves

Select a transition fitting designed specifically for connecting PEX to galvanized steel. These fittings are typically made of brass or bronze, materials compatible with both PEX and galvanized steel. Compression fittings and threaded adapters are common choices. Ensure the fitting is appropriately sized for both the PEX tubing and the galvanized pipe.

Making the Connection: Step-by-Step Guide

Step 1: Shutting off the Water Supply

Before commencing any plumbing work, locate and shut off the main water supply to the section of pipe you are working on. This prevents water from flowing and causing damage or injury. Open the faucet closest to the work area to relieve any residual pressure in the pipes. Confirm that the water is completely shut off before proceeding.

How to Connect PEX to Galvanized Pipe | Full Process Explained

Step 2: Preparing the Galvanized Pipe

Prepare the galvanized pipe by cleaning the threads and removing any rust or debris. Use a wire brush to thoroughly clean the external threads of the galvanized pipe. Inspect the threads for damage. If the threads are excessively corroded or damaged, the pipe may need to be cut and re-threaded, or replaced entirely. Applying thread sealant over damaged threads can lead to failure.

After cleaning, apply thread sealant to the male threads of the galvanized pipe. Use either Teflon tape or pipe dope. When using Teflon tape, wrap the tape clockwise around the threads, overlapping each layer. Apply two to three layers. When using pipe dope, apply a liberal and even coat to the threads. Avoid getting sealant inside the pipe opening.

Step 3: Connecting the Transition Fitting to the Galvanized Pipe

Carefully thread the transition fitting onto the galvanized pipe. Use two pipe wrenches. Securely grip the galvanized pipe with one wrench and use the other wrench to tighten the fitting. Tighten the fitting until it is snug, but avoid over-tightening, which can damage the threads or crack the fitting. Aim for a connection that is tight enough to prevent leaks but not so tight as to cause stress on the joint.

After initial tightening, inspect the connection for any signs of leaks. If leaks are present, slightly tighten the fitting. If leaks persist, remove the fitting, clean the threads, reapply thread sealant, and re-tighten the fitting.

Step 4: Preparing the PEX Tubing

Measure and cut the PEX tubing to the required length using a PEX cutter. A PEX cutter ensures a clean, square cut, which is essential for a proper seal. Avoid using a saw or other tool that could leave jagged edges or debris inside the tubing.

Deburr the end of the PEX tubing after cutting. Use a deburring tool specifically designed for PEX. This removes any sharp edges or burrs that could damage the O-ring or sealing surface of the fitting. A smooth, deburred end is critical for a leak-proof connection.

Step 5: Connecting the PEX Tubing to the Transition Fitting

Insert the PEX tubing into the PEX side of the transition fitting. Follow the manufacturer's instructions for the specific type of fitting being used. For compression fittings, this typically involves inserting the PEX tubing into the fitting until it bottoms out, then tightening the compression nut to compress the O-ring and create a seal. For crimp-style fittings, use a PEX crimping tool to secure the PEX tubing to the fitting with a crimp ring. For expansion fittings, use a PEX expansion tool to expand the PEX tubing before inserting it onto the fitting.

Verify that the PEX tubing is fully inserted into the fitting and that the connection is secure. Gently tug on the PEX tubing to ensure that it is properly seated. Double-check that the compression nut is tightened to the manufacturer's specified torque, or that the crimp or expansion is properly executed.

Step 6: Testing the Connection

Slowly turn the water supply back on. Monitor the connection for any leaks. Start by opening the main shutoff valve slightly to allow the pipes to fill gradually. This reduces the risk of water hammer and potential damage to the connection.

Carefully inspect the connection for any signs of water leakage. Check both the galvanized pipe side and the PEX tubing side of the transition fitting. If leaks are detected, immediately shut off the water supply and address the issue. Minor leaks may be resolved by slightly tightening the fitting. More significant leaks may require disassembly, re-preparation of the pipes and fitting, and reassembly.

Important Considerations

Galvanic Corrosion

Galvanic corrosion can occur when dissimilar metals, such as galvanized steel and copper or brass, are connected in the presence of an electrolyte (water). The more active metal (galvanized steel in this case) will corrode more quickly. Using a dielectric union can help to mitigate this risk by providing an insulating barrier between the metals. However, a transition fitting made entirely of brass or bronze minimizes this concern, as these materials are more compatible with both PEX and galvanized steel.

Plumbing Codes

Always adhere to local plumbing codes and regulations. Plumbing codes vary by jurisdiction and may specify the types of fittings and connection methods that are permitted. Failure to comply with plumbing codes can result in fines, rejection of inspections, and potential safety hazards. Consult with a qualified plumber or building inspector if you have any questions about local plumbing codes.

Professional Assistance

If you are not comfortable performing plumbing work, or if you encounter any difficulties, seek the assistance of a licensed plumber. A professional plumber has the knowledge, skills, and experience to ensure that the connection is made safely and correctly. Improperly installed plumbing can lead to leaks, water damage, and other costly problems.

Conclusion

Connecting PEX to galvanized pipe is a feasible task with the correct preparation, materials, and techniques. Remember these key takeaways:

Accurate Measurement: Correctly identify the sizes of both the PEX and galvanized pipes.
Proper Materials: Use a transition fitting designed specifically for PEX to galvanized steel.
Thorough Preparation: Clean and prepare the galvanized pipe threads carefully, and deburr the PEX tubing.
Secure Connection: Tighten the fitting securely but avoid over-tightening.
Leak Testing: Test the connection thoroughly for leaks after installation.
Corrosion Mitigation: Consider galvanic corrosion and use appropriate fittings to minimize risk.
Code Compliance: Adhere to local plumbing codes and regulations.