Most plumbers, pipefitters, and steamfitters learn their trade through a 4- or 5-year apprenticeship. Apprentices typically receive 2,000 hours of paid on-the-job training, as well as some classroom instruction, each year. In the classroom, apprentices learn safety, local plumbing codes and regulations, and blueprint reading. They also study mathematics, applied physics, and chemistry. Apprenticeship programs are offered by unions and businesses. Although most workers enter apprenticeships directly, some start out as helpers. The Home Builders Institute offers a pre-apprenticeship training program in plumbing and other trades.
Cast iron and ductile iron pipe was long a lower-cost alternative to copper, before the advent of durable plastic materials but special non-conductive fittings must be used where transitions are to be made to other metallic pipes, except for terminal fittings, in order to avoid corrosion owing to electrochemical reactions between dissimilar metals (see galvanic cell).
Jump up ^ "II. The Plumbers". The Atlantic. Retrieved 17 September 2013. In the early evening of June 17, 1971, Henry Kissinger held forth in the Oval Office, telling his President, and John Ehrlichman and Bob Haldeman, all about Daniel Ellsberg. Kissinger's comments were recorded, of course, on the hidden White House taping system, and four years later, a portion of that tape was listened to by the Watergate Special Prosecution Force, which was then investigating the internal White House police unit known as the Plumbers.