How to Replace Galvanized Iron Pipes

Galvanized iron pipe

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Galvanized pipe was normally used in older homes, where it’s used for water supply and small drain lines. It can be recognized by the zinc coating that gives it a silver color and by the threaded fittings used to join the galvanized pipes. Galvanized iron pipes and fittings corrode as they grow old and ultimately must be exchanged. Dwindling water pressure could be an indication that rust has developed inside galvanized pipes. Log jams in galvanized pipes usually happen in elbow fittings; so if you have an obstruction this is likely where the problem is. Don’t try to clean galvanized pipe, replace them instead. Old galvanized iron systems are frequently tricky to replace or mend, especially if fittings are rusted in place, what looks like a tiny job can rapidly become a much larger task to complete. If you think you need extensive repairs, consult a plumber as it might be easier to replace the old galvanized pipes, then repair or replace them. If disassembling a segment of galvanized pipe and fittings, begin at the end of the section and each piece in turn. Reaching the center of a run to swap a piece of pipe can be a time-consuming, dreary procedure. However, a three-piece fitting, referred to as a union, makes it feasible to take out a segment of pipe or a fitting without disconnecting the whole system. When detaching pipes, use two wrenches, one stationary and one turning, position the wrenches so the jaws face opposite directions, and move the one wrench handle towards the opening of its jaws. Read on to learn more.

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Instructions

Difficulty: Moderately Challenging

Things You’ll Need:

Reciprocating saw with metal cutting blade or hacksaw
Wire brush
Pipe wrenches
Propane torch
Nipples
End caps
Union fitting
Pipe joint compound
Replacement fittings (if needed)

Replacing a Section of Galvanized Iron Pipe

Step1

Cut through the section of galvanized pipe to be replaced, using a reciprocating saw with a metal-cutting blade or a hacksaw.

Step2

Make sure the fitting stays stationary with one pipe wrench, and employ another to detach the old galvanized pipe. Remember the jaws of the wrenches should face opposite directions.

Step3

Do away with any corroded fittings via two pipe wrenches, one to twist the fitting and the other to clasp the pipe firmly in place. Then clean the threads of the pipe with a wire brush.

Step4

Heat intractable fittings with a propane torch for trouble-free removal. Make sure to safeguard all combustible substances with a double layer of sheet metal and apply the flame for 5 to 10 seconds.

Step5

Spread pipe joint compound equally over the threads of all pipes and nipples to be joined. Use two wrenches to tighten the new fittings onto the pipes, leaving them 1/8 turn out of alignment.

Step6

Screw the first nipple into a fitting and tighten it with a pipe wrench. Slip a ring nut onto the nipple, screw the hubbed union nut onto the nipple, and tighten it with a pipe wrench.

Step7

Screw a second nipple onto the other fitting and tighten it with a pipe wrench.

Step8

Screw threaded union nut onto second nipple and tighten until snug. Line up pipes so the lip of hubbed nut fits inside the threaded union nut.

Step9

Complete the connection by screwing the ring nut onto the threaded union nut and then tighten the ring nut until snug.

Tips & Warnings

Make sure to measure old pipe before replacing it. Add 1/2 inch at each end for the pipe threads that extend inside the fitting.
Make sure to bring the over-all measurement to the store when buying parts.
Use a union fitting and two threaded pipe nipples to replace a section of old pipe. Remember when assembled, the union and nipples must equal the length of the galvanized pipe being replace.
Make sure not to confuse galvanized iron with black iron, which is available in similar sizes and has similar fittings, but black iron is used only for gas lines.