PBT – flexible (usually gray or black) plastic pipe which is attached to barbed fittings and secured in place with a copper crimp ring. The primary manufacturer of PBT tubing and fittings was driven into bankruptcy by a class-action lawsuit over failures of this system.[citation needed] However, PB and PBT tubing has since returned to the market and codes, typically first for "exposed locations" such as risers.
Although plumbers, pipefitters, and steamfitters perform three distinct and specialized roles, their duties are often similar. For example, they all install pipes and fittings that carry water, steam, air, or other liquids or gases. They determine the necessary materials for a job, connect pipes, and perform pressure tests to ensure that a pipe system is airtight and watertight. Their tools include drills, saws, welding torches, and wrenches.
Those who attempted to bring plumbing indoors faced technical as well as attitudinal challenges. Decisions on how wastewater was removed required as much concern as those made to ensure an adequate water supply. But equally vexing was the prevailing miasma theory of disease, which held that illnesses stemmed from "bad air" that was readily identifiable by its offensive odor. This led to a distrust of early indoor plumbing that tended to leak and a deadly fear of the sewer gas that accompanied the leaks. It is no wonder then that many individuals maintained a strong belief that elimination was best taken care of out of doors.

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