Pipe, Fittings, and Valves

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PIPE INSULATION

Heat is lost from non-insulated water pipes. That means lost energy and increased heating costs, frozen pipes in winter and condensation dripping from water pipes.

Pipe insulation corrects these problems. Pipe insulation can also help maintain water temperature in the pipelines to avoid letting water run to reach desired hot or cold temperature.

Wrap-on insulation includes fiberglass pipe wrap with a separate vapor-sealing tape, which must be wrapped around the fiberglass.

Plastic cork wrapping needs no separate vapor seal since it will not absorb moisture and is waterproof. Other wrap-on insulation includes vinyl foam, aluminum foil and polyethylene-coated duct tape.

Foamed plastic tubing for covering pipes costs more than wrap-on types. However, the finished job is generally neater looking and the material is somewhat quicker to install. It is available in sizes to fit either galvanized pipe or copper tubing.

Mastic compound can be used to insulate large diameter pipes, cold-water tanks and similar surfaces which may be subject to condensation. Available in one-gallon cans (which will cover approximately six sq. ft.), this thick coating is applied in layers at least 1/4" thick.

HEATING CABLES

Two types of heating cables are series and self-regulating. While both types of cables have a similar appearance, plug into electrical outlets, and wrap around pipes, the actual functioning and installation techniques are very different.

Series cables' heat is generated by a current-carrying wire, and is maintained at a temperature that does not vary with the environment. Series heaters are available in pre-assembled lengths from 2' to 100'.

Because of the heating element, you cannot cut it to length yourself. It cannot be overlapped onto itself without burning out, so be sure to purchase the right length.

Most series heaters cannot be used on plastic pipes. And while some series heaters can be used with insulation, some cannot.

Self-regulating heating cables generate heat through the plastic material between the current-carrying wires. These heating cables regulate themselves automatically, providing more heat as outside temperatures drop and less as temperatures rise.

Self-regulation allows the cable to be overlapped. The heating cable is typically on a reel in a store, and you cut off only what you need. Separate connection kits can be purchased and put together by yourself at home. Some self-regulating brands also come in pre-assembled, shorter individual lengths. Self-regulating heaters can be used on plastic pipes, and should be used with thermal insulation.

Both types of heating cables must be protected from mechanical damage and from water. And both should be used with a ground-fault circuit interrupter (GFCI) with a 30mA trip level.

PIPE-JOINT COMPOUND

When selecting pipe-joint compound, you need to know what the pipe will carry after installation-natural gas, oil, gasoline, water, or any other fluids or gases.

An advantage of commercially prepared pipe joint compound is its ability to seal all joints, yet make disassembly easy, to prevent seizure of parts by rust and corrosion.

Pipe-joint compounds come in 1-oz. tubes up to brush-on cans or 50-gal. drums.

One form of pipe-joint compound is Teflon tape, which comes in rolls; standard widths are 1/4", 1/2" and 3/4", and lengths range from 30' to over 100'.

Special compounds are also available that are fast drying and hard setting.

Certain plastics are attacked by pipe compounds so be sure the compound is specifically recommended for any plastic material it is used with.

FITTINGS

Fittings allow the you to install pipe in the proper place and terminate it at the right spot. Although each kind of pipe requires its own type of fitting, there are similarities among all fittings. Understanding the proper application for each can save you time, material and labor.

There are two basic designations for pipe fittings: male and female. These refer to the threading. Male threading is on the outside and threads into the female threading which is on the inside of the fitting.

Nipples - extend a line or provide proper threading at the right location. Nipples come in diameters ranging from 1/8" to 4" to match standard pipe diameters and in lengths from close (nipples that are threaded on both ends to a point where threads almost join in the center) through 24". Normal size increments are even inches. Long nipples or "cut lengths of pipe," which are threaded on both ends, are available in about 24" lengths, usually increasing in length by 6" increments (30", 36", 42", etc.).

Couplings - connect all standard sizes of pipe. Tight seal with a pipe wrench and pipe-joint compound will waterproof connection.

Bushings - inserted inside a coupling to reduce the size of the pipe. With a coupling, a run of pipe can be reduced a size or two; with a series of bushings, any number of reductions can be made.

Floor Flanges - connect pipe to a wall, floor or any flat surface. Flanges are threaded onto pipe and tightened. This provides a flange rim with four screw holes, making it easy to fasten pipe to a flat surface.

Elbow - change direction of pipe. Most common are 90 degree and 45 degree elbows, which have inside threads on both ends. A street elbow has inside thread on one end and outside thread on the other.

Reducers - reduce pipe size. Bushings screw into a coupling while reducers screw directly onto pipe threads. Some reduce pipe only one size; others can reduce several sizes.

Side-Outlet Elbows - have three-way outlets. Can be used as corner pieces for railings, fences, etc. Also used for pipe connections on corner construction.

Crosses and Tees - available in all sizes and shapes. Most common is straight tee which has three inside threads of the same size which can be used to run three pipes in a "T" shape. Reducing tee has same shape, but two straight ends of the "T" are reduced one size or more.

Four-Way Tee (Side Outlet) - similar to the side-outlet elbow except side outlet runs through the elbow with an opening of the same size on each end. Straight cross has four outlets for pipe of the same size. Side-outlet cross has an opening on the side for a fifth pipe of the same size.

Return Bends and Y Bends - return bends are made in close, medium and open patterns. The close is a sharper bend than the medium and the medium is a sharper bend than the open. The Y bend is a straight or reduced outlet which permits connecting pipe of the same or reduced size to a 45 degree angle.

Ground Joint Union - three-part fitting that connects any standard size pipe where it may be necessary to disconnect later. Because of the bronze-to-bronze or bronze-to-iron ground-joint seat, it can be taken apart and reassembled at the nut with a pipe wrench and no pipe-joint compound.

COPPER-PIPE FITTINGS

Fittings for copper pipe must be soldered on at least one end, leaving one or both ends unthreaded. After flux has been applied, solder is introduced at the edge of the fitting. It is then drawn, by capillary action, the full depth of the fitting to completely surround the tube.

The result is a strong, leak-proof, bonded joint. The solder is usually applied with a propane torch, a process known as "sweating" fittings.

Appliances that use a small amount of water, such as evaporative coolers and humidifiers, use a small size slip joint tee and saddle tee. A slip-joint tee is installed by cutting the line and spreading it slightly. The saddle tee clamps onto the line and a hole is drilled in the pipe through the side opening.

A commonly used fitting in installing dishwashers is the three-way compression stop. This fitting, installed on the hot or cold sink supply line, will cut the flow of water to both appliances at the same time.

PLASTIC-PIPE FITTINGS

Plastic fittings for plastic pipe, metal fittings for plastic pipe and fittings for connecting (transmitting) plastic to metal pipe are available in threaded, insert, compression and solvent weldable types.

Threaded plastic fittings thread exactly like metal fittings; however, special transition fittings should be used to connect plastic to metal pipe in hot and cold water systems to prevent leaks caused by the different expansion rates of plastic and metals.

Insert fittings are sometimes used with flexible plastic pipe such as polyethylene. Insert fittings are inserted into the pipe and sealed with an adjustable clamp.

Solvent-weld fittings have specially formed sockets into which plastic pipe is inserted. Fitting and pipe are bonded by a chemical weld using the solvent or cement compatible with the type of plastic being connected.

Manufacturer's recommendations should be followed in making such joints. When done properly, these joints form a permanent weld stronger than the pipe itself.

INSTANT-CONNECT FITTINGS

Instant connect fittings make it easy for you to join tubing or pipe. The homeowner inserts the tubing or pipe into the fitting until it seats then pulls back to ensure a tight fit. These fittings are tested up to 600 psi and come in a full range of types to connect copper, polybuty-lene, CPVC and galvanized pipe in 3/8", 1/2" and 5/8" outside diameter. The fittings are easy to use; but once in position and seated, the fitting cannot be removed for realignment.

SOLDER AND FLUX

Solder is used to "sweat" copper and brass fittings; it forms a bonded joint between fitting and pipe.

The specified material for sweat soldering used to be 50/50 (50% lead and 50% tin by weight) or 60/40 (60 % lead and 40 percent tin by weight). However, in 1986 the U.S. Congress banned the use of lead containing materials in public water supply systems and in any plumbing providing drinking water connected to public water systems. As specified by law, all of the States prohibited the use of lead-containing materials in the repair or construction of public water-supply systems. The major U.S. plumbing codes were revised to exclude the use of materials containing lead from potable-water applications.

Among the materials prohibited by law in public water systems is lead solder and flux, defined as those containing more than 0.2 percent lead. In 1986 Congress amended the Federal Hazardous Substance Act, defining lead solder as a hazardous substance. The law requires manufacturers to place warning labels on packages of lead solder introduced into interstate commerce.

Now the specified materials for sweat soldering are "lead-free" solid-wire solders. Lead-free solders contain no more than 0.2% lead. There are a number of lead-free solders available, including 95/5 tin-antimony or tin-silver solders. The first number denotes the percentage of tin. Most of these lead-free solders are formulated by the manufacturers to approach or equal the ease of its application and performance of the traditional lead solder.

Flux (liquid or paste) is necessary for anyone buying sweat fittings. So is a small brush to apply the flux. As with solders, fluxes utilized in the soldering of potable water piping must be lead free.

Used along with solder, flux prevents oxidation of metals as they are heated. It also chemically cleans the surface of items to be soldered after they have been rubbed clean with sanding paper or a wire brush.

By preventing oxidation, flux allows solder to flow freely, forming a good bond.

MAPP GAS

To get a good sweat fitting there should be no water in the pipeline; some homeowners find it difficult to thoroughly drain the line.

This may cause a problem if you are using a propane torch which does not generate enough heat to dry out the line. MAPP gas, however, reaches a much higher heat that can dry out small amounts of water.

Because of this intense heat, MAPP gas must be used carefully, it can melt the copper if held too long in one spot.

VALVES

METAL VALVES

Valves, sill cocks and faucets control the water supply. Valves and sill cocks are used on pipe lines; faucets are installed on fixtures.

Valves in home plumbing lines usually are cast bronze and have portions machined and threaded for trimmings.

Gate valves have a sliding wedge that is moved across the waterway, usually by a threaded spindle or stem. It is either rising or non-rising, the latter having a shorter bonnet.

A gate valve is used to completely shut off or open a waterway, but not control the volume of flow. Either opening of a gate valve may face the pressure side of the line.

Gate valves allow complete passage of water and should be used on supply lines that are in constant use.

Globe and angle valves are used when a valve must be opened and closed frequently under high water pressure. Globe valves are used to control volume of flow. They have two chambers with a partition between them for passage of water which must change course several times from port to port. Globe valves should not be used in water supply lines for occasional shutoff purposes.

An angle valve is similar to a globe valve, but has its ports at right angles. Water passage is greater than through a globe valve; since there is only one change in direction of flow, less resistance occurs. An angle valve installed at a turn in piping eliminates the necessity of an elbow and is often preferred to using a globe valve and elbow.

Plug and key valves are better known as straight stops. These have tapered ground plugs that seat into matched tapered ground bodies. Plugs have flat heads, square heads or socket heads; the other end is threaded to hold a hex nut and friction-ring combination. This is mounted over a tension spring inside the body that keeps the plug tight.

They are manufactured in brass, bronze, galvanized iron-bodied and black iron-bodied and are used mostly as gas stops.

Drainable valves or stop and waste valves have a small opening on the non-pressure side to allow drainage when it is in cutoff position. It is sometimes called a bleeder valve and may be obtained in threaded, sweat, flare and slip-joint ends. The latter two are municipal and emergency valves. Most are flat head or socket head; common residential types have socket head that takes 3/8" key rod.

Check valves operate automatically, permitting flow in one direction only. They are sometimes combined with a throttling or shutoff valve. Some communities require a check valve in cold water lines between the water heater and meter.

Check valves are used to prevent water pumped to an overhead tank from flowing back when the pump stops. Some check valves are designed for use with vertical pipes only. Therefore, correct installation is essential. The closing device-a disk, ball or clapper-falls shut by gravity when installed vertically.

Swing-type check valves serve the same purpose as check valves. A small, smooth swing-type gate is located in the center of valve. As water is pumped through the flow side of valve, the gate swings open to allow passage of water. If water attempts to back up through the valve, the gate is forced shut against the pressure side of the valve.

PLASTIC VALVES

Plastic valves are made of CPVC, PVC and ACETAL. The plastic valves available are gate valves, universal-line valves, straight-supply valves, angle-supply valves, washer-hose valves, angle valves and sill cocks.

One type is molded of ACETAL plastic and has threaded connections for use in metal-piping systems. The other type, molded of CPVC or PVC plastic, is either threaded or non-threaded and has solvent-weld connections. These are used in plastic piping systems. However, PVC gate valves and ball valves can be purchased both threaded and non-threaded

Like plastic pipe fittings, solvent-weld valves (connections made by cement) must be used with compatible plastic-piping systems; i.e. PVC valves used in a PVC piping system.

Threaded-connection ACETAL valves, which can be used in most applications in which metal valves are used, are available in globe (stop), stop and waste, boiler drain, sill cock and sink faucet. Plastic valves should not be used in steam, gas or compressed air lines. However, valves can be used with hot- and cold-fluid systems.

The ACETAL valves perform at temperatures of -20 degrees F to 180 degrees F. They can withstand pressure up to 150 lbs. and are excellent for hard-water areas because they resist mineral buildup.

Since handles are made of plastic, heat is never absorbed from the water line. No brute force is required to install them. Because the threads are more precise than machined threads on a metal part, the installer can mate the parts one to two threads beyond normal makeup on a metal joint for a better connection.

A "double seal" feature allows the washer to be removed, leaving the plastic seat to maintain the integrity of valve. If there is danger of the washer or metal parts deteriorating, it is recommended that installation be made without the washer.

Solvent-weld CPVC and PVC valves offer similar benefits to the ACETAL valves. These are available in globe (stop) and boiler drains. Gate valves and ball valves are available in PVC and CPVC.

When using a plastic valve as a retrofit with another piping material, it is best to use a transitional connector to prevent leaks caused by the differing contraction/expansion characteristics of the two materials.

Newer CPVC valves make a mechanical connection to plastic or metal material. The mechanical valves are easily installed and result in a leak-free connection. There is no solvent welding, sweat soldering or pipe threading; the mechanical coupling on the CPVC valve is loosened, pushed on and hand tightened.

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Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.

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