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Using Compression Fittings

Use compression fittings in places where you may need to take the run apart someday or where it is difficult to solder. One common location is on supply lines for a sink, which have compression fittings at both the stop valve and the faucet inlet. Flexible supply lines are an even easier way to make this connection. Compression fittings usually are used with flexible copper tubing, but may also be used with type-M rigid copper. These fittings are not as strong as soldered joints so they should not be hidden inside walls.

1 .To join a compression union, position the parts. Bend the tubing pieces into position and slip a nut and a ferrule onto each piece of tubing. Smear pipe joint compound on the ferrules and on the male threads of the union. Slide the pieces together, and hand-tighten the nuts.

2. Tighten the nut. Tighten the compression nut with a wrench, forcing the ferrule down into the tubing to secure and seal the connection. If the joint leaks when the water is turned on, tighten the nut a quarter turn at a time until the leak stops. Don’t over-tighten the joint—too much pressure can crush the tubing or crack the nut.

1 .To make a compression joint, position the parts. Bend the tubing into position, and slip on the nut and the ferrule. The ferrule will not go on if the tubing end is bent or out of round. You may have to sand the tubing with emery cloth to get the ferrule to slide on. Smear pipe joint compound on the ferrule and the male threads of the union. Slide the pieces together, and hand-tighten the nuts.

2. Tighten each side. Place one wrench on the union. Use another wrench to tighten each side. Once snug, tighten about a half turn more. Turn on the water; if there is a leak, gently tighten more.

How it works - The compression nut forms a seal by squeezing the ferrule against the copper pipe. Because copper is a soft metal, the seal can be extremely tight. Still, use pipe joint compound to make sure the seal is watertight. Anchor or support the tubing within 2 feet of either side of the fitting.

Using Flare Fittings

Flare fittings, like compression fittings, are useful in places where it’s difficult to solder a joint. Do not hide flare fittings inside a wall. You can use flare fittings only with flexible copper tubing; they cannot be used on rigid pipe. Unlike compression fittings, this type of fitting requires a flaring tool. The two-piece tool reshapes the end of the copper tubing, “flaring” it to fit into a special flare fitting. If possible, make the flared connection first, then cut the tubing to length because sometimes tubing splits while being flared.

1. Flare the tubing ends. Make sure the tubing is cut square across. Also remember to slip the flaring nut on before you flare the end of the tubing. Choose the hole in the flaring block that matches the outside diameter of the tubing. Clamp the tool onto the tubing. Align the compression cone on the tubing’s end and tighten the screw. As you turn the handle, the cone flares the tubing’s end. Inspect your work carefully after removing the tubing from the flaring block. If the end has split, cut off the flared portion and repeat the process.

2. Assemble the pieces. Seat the flare union against one of the flared ends of the tubing, slide the nut down, and hand-tighten. Do the same on the other side. No pipe joint compound is necessary.

3. Tighten and test. Place one wrench on the union and one on a nut. Don’t over-tighten a flared joint. Once snug, give a half turn on each nut. Turn the water on and test. If the joint leaks, tighten it carefully until the leak stops. If tightening won’t stop the leak, dismantle the joint and examine it to see if the tubing was cut squarely. Make sure that the nut was not cross-threaded on the fitting. Anchor or support the tubing within 2 feet of either side of the flare fitting.

Removing Old Threaded Pipe

After your first experience with threaded pipe, you’ll appreciate why this material is all but extinct in new installations. Cutting, threading, and assembling steel pipe requires muscle. Sometimes when you’re trying to take old pipe apart, you’ll swear it is welded together. If your home was built before World War II, its supply pipes are likely to be threaded steel. This doesn’t mean you have to use the same pipe for improvements or repairs. Special fittings let you break into a line and add copper or plastic. Black threaded pipe, which lacks the shiny gray color of galvanized, is meant for gas only and is still commonly used. Do not use black pipe for water lines.

Switching Materials - If you have good water pressure and can find no serious rust, there is no need to replace your threaded steel pipe with copper or plastic. But if water pressure is low, aerators fill up with rust, and leaks develop, it is time for a change. Replace the worst-looking pipes first. Don’t cut holes into walls and get involved in a major refit unless it is absolutely necessary.

1. Start at a union. NOTE: Shut off water, and drain the pipes. Examine the way your pipes and fittings thread together and you’ll see you can’t simply begin unscrewing them anywhere. Somewhere in every pipe run is a union that allows you to unlock and dismantle the piping. To crack open a union, determine which of the smaller union nuts the ring nut is threaded onto. Use a wrench on the union nut to hold it stable. Put another wrench on the ring nut to turn it counterclockwise. Once it’s unthreaded, you have the break you need and can start unscrewing pipes from fittings.

2. When necessary, cut the pipe. If there is no union handy, cut a pipe with a hacksaw or a reciprocating saw fitted with a metal-cutting blade. When you reassemble this run you’ll have to install a union using pre-threaded nipples on either side of the union.

3. If the pipe won't budge - Stubborn joints may respond to penetrating oil, or try heating the fitting with a propane torch. Then use a larger pipe wrench, or slip a piece of 1 1/4 inch or 1 1/2-inch pipe onto the handle of your wrench to increase its leverage.

Installing Threaded Pipe

If you choose to work with threaded pipe, one difficulty is ending the run at the right place. Because the ends of the pipe are threaded, you can’t just cut a piece to fit, as with copper or plastic. Purchase long pieces that take up most of the runs and have on hand plenty of couplings and a selection of nipples—or short lengths of pipe that are threaded on each end. You will then have a number of options to choose from to end the run in the right spot.

Boosting Pressure

  • Poor water pressure in an old house may be due to galvanized pipes that are clogged with rust. If the problem is limited to one fixture, try replacing a few of the pipes leading up to it. If the problem is throughout your house, call in a professional.
  • There are companies that specialize in unclogging galvanized pipe. They use a process that causes rust and corrosion to fall away from the inside of the pipe. The process can take months, will clog faucets, and may require repairing leaks found as gunk plugging holes is removed. In the end, however, water will flow through your pipes as if they were new.

Assembling the parts - This typical installation combines standard-length pipes with joints and nipples to end up exactly at the right location. For background on measuring pipe accurately. Many plumbing suppliers have ready-cut galvanized pipe in standard sizes—12 inches, 48 inches, and so on—for less cost and delay than having pieces custom-cut. Try to use these pieces; if you make a mistake in measuring, you may not be allowed to return a custom-cut piece.

Joining the pieces - Before you thread a pipe and fitting together, seal the pipe threads using pipe joint compound or Teflon tape. Assemble the pipes and fittings one at a time, tightening each as you go. If your assembly requires a union, work from each end toward the union. The union is installed last. Support runs of threaded pipe at least every 6 feet.

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