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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