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Polybutylene Plumbing
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Polybutylene plumbing inside a structure ("PB In-House Plumbing") is a potable water supply system containing polybutylene ("PB") pipe and either acetal (plastic) or metal insert fittings (such as tees, and elbows). PB pipe is a non-rigid, sometimes curved, usually gray (or possibly silver or black) plastic pipe. When used in the underground service from the water company to a structure (a "Yard Service Line"), PB pipe is blue, gray or black. PB pipe is not used for drains, waste or vent piping. Also, PB pipe is not PVC or CPVC, which is a rigid white or off-white plastic pipe. "PB Plumbing" refers to both PB In-House Plumbing and Yard Service Line.
Insert fittings are used to join pieces of polybutylene pipe. The insert fitting is inserted into the pipe and clamped with a metal (aluminum or copper) crimp ring over the outside of the pipe. Metal insert fittings are either copper or brass. Acetal insert fittings are hard gray or white plastic. They are not black. Insert fittings are not grabber, flare or compression fittings, which are often threaded and use a plastic or metal nut to secure the seal.
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Introduction
Polybutylene plumbing (PB or PolyB) is a flexible, easy-to-cut, gray, plastic pipe with joints secured with either epoxy or insert fittings and metal crimp rings. PB was introduced in the late 1970s for use in residential plumbing. Less expensive in material cost and easier to install than traditional copper plumbing, PB has been used to pipe approximately six million homes in the U.S. However, there is considerable concern surrounding PB's potential to leak. Though there is no specific data to indicate an inherent problem with the pipe itself, a number of homeowners have encountered minor to severe leaks, which has led to various lawsuits against PB manufacturers in the U.S. |
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Fitting
The primary concern with PB plumbing has been the fittings, which connect the 10-foot or shorter sections of pipe. The original acetal resin-based fittings are suspected of deteriorating when exposed to chlorinated water. In addition, crimp rings, which apply pressure to the PB pipe seal the PB to the fitting, made this section of the system more susceptible to failure when the plastics deteriorated. The industry first blamed all problems on faulty installation, but lately has acknowledged that the plastic fittings have been a major problem. The original barbed insert fittings made with an acetal resin and the type of fitting and crimp rings used have undergone numerous changes. The original aluminum crimp rings were changed to copper; the crimping tool was redesigned several times; and the acetal fittings were replaced with the copper and brass fittings that are still in use today.
Piping
Though the primary focus of the debate has revolved around the fittings, PB pipes have also undergone modification to produce a stronger, more durable product. Premature deterioration and failure of the pipe has occurred.
There are many theories on the cause of the premature deterioration and failure of the pipe. One theory is that when the piping is stored outdoors for a period of time or exposed to sunlight after installation, ultraviolet (UV) radiation from sunlight adversely alters the chemistry of the plastic, causing deterioration. The second theory for the premature deterioration and failure of the pipe is a reaction to oxidants (e.g. chlorine) in the drinking water. However, no studies or information can support those theories at this time. The manufacturers, even today, continue to maintain that the failures with the PB tubing are due to installation errors and/or misuse rather than product failure.
Heating Systems
A secondary concern involves the use of PB pipe for hot water heating systems. The pipe allowed the oxygen to penetrate the pipe and oxygenate the water. The additional oxygen in the re-circulated water was suspected of causing the premature rusting and deterioration of the internal components of the heating unit, including the boiler, heat exchanger and water pump. The PB pipe has since been modified with a coat to prevent oxygen from penetrating the pipe walls.
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