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Pipe, Fittings, and Valves

These materials may be made of metal or plastic. Plumbing components made of bronze and brass contain 3% to 8% lead. Lead serves two purposes in the copper alloys from which these materials are manufactured. First, lead aids in the manufacturing process by providing lubrication and preventing chipping during the metal-working process. Second, the lead in the alloy improves product performance. Federal law limits the amount of lead to 8% that may be contained in plumbing materials, except flux and solder, installed into public water-supply systems.

Lead compounds may also be present in some plastic plumbing components. Lead may be used in the manufacture of the plastic plumbing products as a plasticizer. Plastic plumbing components that are certified by the NSF International do not contain lead. Plastic materials certified by NSF are recommended for potable water plumbing applications.

PIPE

The heart of home plumbing systems is pipe, whether for supply or waste drainage. Waste piping is always larger than water pipes, which tend to be smaller than 1" in dimension. Normal inventory consists of four kinds of pipe-steel, plastic, copper and soil.

STEEL PIPE

Steel pipe is used primarily for carrying water, steam or gas. Available in both black and galvanized finish, it is made of wrought steel and sold in sizes from 1/8" to 6".

Galvanized pipe is commonly used for water systems, black pipe for manufactured and natural gas. Galvanized pipe should never be used for gas installations. Plumbing codes in many areas require that black pipe, especially that used underground, be coated and wrapped.

PLASTIC PIPE

Because it is easy to work with, lightweight and durable, plastic pipe is popular among do-it-yourselfers. Installation costs are usually lower for plastic materials, but in some areas its use in home plumbing systems is restricted; check on where and how local codes will allow plastic pipe to be used.

Polyethylene and polybutylene plastic pipe is flexible and can be cut with a pocket knife or a special cutter. One of the major advantages of plastic pipe is that it will not rot or corrode.

A disadvantage for some types, such as flexible polyethylene, is that it cannot be used for hot-water lines. Any plastic pipe used to carry drinking water should have the seal of the National Sanitation Foundation.

Following is a list of common plastic pipes and their characteristics.

Polyvinyl Chloride (PVC) - excellent chemical resistance, good crush resistance and impact strength, fire resistant (self-extinguishing). Is functional up to 120 degrees F in pressure systems and 180 degrees F in non-pressure systems, such as drain, waste and vent (DWV) applications.

Used in pressure supply and drainage systems to carry water for uses such as golf-course sprinklers and agricultural irrigation, and in underground gas-distribution systems, industrial and chemical piping, corrosive fume ducting and crude-oil transportation.

Chlorinated Polyvinyl Chloride (CPVC) - excellent chemical, crush and fire resistance, high-impact and tensile strength, and is nontoxic; CPVC can be used for hot and cold-water applications. Functions at 180× F in pressure systems and at higher temperatures in low- and non-pressure systems. CPVC does require a special solvent cement different from cement used for other types of plastic welding.

It is used in hot and cold water-supply systems and hot and cold chemical-distribution systems.

Polyethylene (PE) - excellent chemical and crush resistance. Has high impact strength and flexibility and good low-temperature performance. Functions in temperatures from -65o to 120 degrees F in low-pressure applications and to 200 degrees in non-pressure applications.

PE is used in low-pressure water systems, such as golf-course sprinklers; to carry corrosive liquids and gases; as underground conduits and gas-pipe reliners; in industrial and chemical laboratory drainage systems, and underground gas piping. Perforated PE is used as a corrugated drainage pipe for foundation drainage.

Polybutylene (PB) - only flexible plastic tubing suitable for use with hot and cold water in pressure systems. PB has excellent chemical resistance to acids and alkalis, but is not suited for fuel oil, gasoline or kerosene distribution systems.

Polybutylene can be joined with heat fusion, flare or compression fittings. However, it is not solvent weldable. Several plastic fitting designs are available for use with PB.

Polybutylene has excellent strength characteristics. Manufacturers of PB claim that should water freeze inside, the tubing will not burst. However, some fittings used with PB will break under ice expansion.

PB is rated to function at 180× F up to 100 psi; higher temperatures can be tolerated with a relatively small reduction in pressure.

Acrylonitrile-Butadiene-Styrene (ABS) - good chemical resistance, excellent impact strength, especially at low temperatures and maintains rigidity at higher temperatures. Maximum functional temperature is 180 degrees for non-pressure systems.

ABS is used in mobile home and residential drainage systems to provide gas service and as underground electrical conduits.

Rubber Modified Styrene (SR) - good crush resistance, fair impact strength and moderate chemical resistance. SR is lightweight but brittle at low temperatures. Functions at a maximum of 160 F.

SR is used for drainage and sewage systems, underground downspout drains, underground electrical conduits, septic-tank absorption fields and foundation drains.

Polypropylene (PP) - excellent chemical resistance, resistant to sulphur-bearing compounds, lightweight, good tensile strength and saltwater resistance. Stronger and more rigid than polyethylene with a higher functioning temperature (190 degrees F), polypropylene is popular as a material for tubular products, such as P-traps, because of its high chemical resistance.

Polyacetal (ACETAL) - excellent resistance to paraffins and solvents, high resistance to surge fatigue, nontoxic and approved for potable water. ACETAL is used for process systems; solvent handling; agricultural chemicals, crude-oil and natural-gas distribution systems.

Polyacetal is also used to manufacture faucet bonnet and valve stems.

Although there are many types and sizes of plastic pipe available, the most popular for home use is flexible polyethylene pipe with 1/2", 3/4" or 1" inside diameter. This pipe is lightweight and can be cut with an ordinary sharp knife or a fine-toothed hacksaw blade.

When metal pipe is buried underground, care must be taken to drain water before temperatures drop below freezing. Otherwise, both pipe and fittings would rupture when freezing water expands.

These precautions are not necessary with flexible plastic pipe. It can be buried a few inches below the surface or deep enough to protect the pipe against accidental damage from digging or cultivation.

To install flexible plastic pipe, the homeowner simply unrolls a coil of plastic pipe; couplings are not required unless the pipe is cut.

Semi-rigid and rigid plastic pipe, which is sold in 10' to 20' lengths, does require coupling.

Depending on the chemical composition of the pipe, pieces are joined with an insert coupler using metal straps to hold the coupling to each section of pipe or with a coupler that is sealed with a pipe cement. This cement creates a chemically fused bond between coupling and pipe that is as strong as the pipe itself. The exception is PE, which cannot be welded with cement.

Most plastic pipe can be joined with and worked into metal plumbing with the use of proper adapters or transition fittings.

Rapid technical advances in the manufacture and use of plastic pipe have made it imperative for consumers to follow the manufacturers' information on use, installation and pressure ratings of the pipe and fittings.

One area where these changes are most evident is in supply tubing. Supply tubing has gone through a metamorphosis from copper to corrugated copper to polybutylene and vinyl supply tube. Vinyl supply tubing is easy to hook up, and with its flexible "give" will alleviate a mild water-hammer condition created by many single-lever faucets with quick shutoff. Stainless-steel braided flexible supply connectors are another form of supply tubing. Stainless-steel braiding encases a nontoxic synthetic polymer or neoprene rubber core suitable for both hot and cold water.

Manufacturer claims include high-burst pressure ratings (1,500 psi to more than 2,400 psi), resistance to embrittling, and crimping on fittings that won't creep or blow off.

No cutting or flaring is involved which eliminates pipe bending, soldering and special tools.

Stainless steel braided connectors are available for faucets and toilets as well as for water heaters, water softeners, dish and clothes washers, hot tubs, etc.

Similar connectors use nylon braiding which offers a reduced burst pressure in the 600 psi range.

SOIL PIPE

Soil pipe is made of vitreous clay, bituminous fiber, plastic, drainage type copper (DWV), or cast iron. Each has certain advantages depending upon location, soil types and price. Copper and cast iron are more expensive, but serve better where rigidity is a must or where tree roots are massive enough to crush fiber or enter clay joints.

Copper and plastic (where permitted) have advantages of prefabrication and long lengths. Cast iron pipe also comes in longer lengths.

COPPER PIPE

Copper pipe - is manufactured in five general grades and thicknesses.

Type K - heaviest; used in municipal, commercial and residential construction.

Type L - lighter than K; used most often in residential water lines. K and L are manufactured in hard (rigid 20' lengths) and soft (60', 100' and 200' lengths, the latter in smaller sizes).

Type M - hard (20' lengths and under). Recommended for light domestic water lines and is not permitted in some city codes.

Refrigeration - 50' coils and rigid 20' lengths. Most refrigeration copper has moisture removed and ends sealed for better performance of refrigerants. It is often used in heater connectors, but has a tendency to build a crust of corrosion on the inside if gas has any trace of sulphur. Flexible brass or soft-aluminum pipe seems to be more efficient for gas transmission to household heating and appliances.

Type DWV - drainage, waste and vent; rigid only and comes in 20' lengths.

Type K, L, M, and DWV copper sizes are listed in nominal dimensions; refrigeration copper sizes are listed in outside dimensions. All copper is normally corrosion resistant and easily assembled with proper tools.

TRAPS AND TUBULAR GOODS

TRAPS

Plumbing fixtures are equipped with either a P or S trap, which is frequently fitted with a clean-out plug on the bottom. The trap bend holds water which prevents odors from backing up into the home.

Drum and bottle-type traps for bathtubs or kitchen sinks consist of a cylindrical metal box or settling basin attached to the waste pipe. They are generally provided with a screw-cap cover that can be removed when cleaning is necessary.

In most areas 1-1/4" chrome-plated brass traps are used in lavatory drains, and satin-finished or nickel-plated brass 1-1/2" traps are standard equipment on residential kitchen sinks. (Satin finish is unpolished chrome-plated tubular).

Plastic P and J traps can be used in retrofit as well as new plumbing work with adapters and transitional couplings to connect plastic with other materials.

Corrugated flexible plastic drain is useful when installing new sinks or vanities with older drain systems. Many times the drain from a new installation will not line up with the old drain pipe. Corrugated, plastic drain pipe allows the d-i-yer to connect misalignments by as much as several inches.

TUBULAR GOODS

Garbage disposers, dishwashers and special kitchen sinks require tubular brass goods including P traps, S traps, J bends, repair traps (with slip-joint nuts on both ends), continuous wastes for sinks with double compartments, tailpieces that connect sink strainers to continuous wastes, branch tailpieces that connect dishwasher drains to sink wastes, extensions to slip (straight tube lengths with slip-joint nut), and extensions to solder (straight tube with bell end for a sweat extension).

These are primarily used in adding disposers to existing sinks. There is a fair market for 1-1/4" threaded tailpieces that extend lavatory wastes to the correct distance for trap connection.

Fittings for tubular brass consist almost entirely of 45 degree ells, 90 degree ells, couplings and tees in 1-1/4" and 1-1/2" sizes-all with slip joint nuts and washers. Strap wrenches are recommended for most work with chrome-plated brass.

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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.