Copper is much used for small and medium-sized steam pipes which are subjected to moderate pressures, and for pipes to convey salt water and other liquids. This material is easily worked, is non-corrosive for all ordinary uses, and is particularly adopted for pipes which must have many crooks and bends to fit in confined spaces. Copper pipes often suffer in marine use from galvanic action, and tinning is much resorted to for protecting them.
The larger sizes of pipes are made of sheets of medium-hard rolled copper bent to cylindrical shape and brazed along the scarfed edges. Copper pipe up to 8 inches in diameter is made from seamless-drawn copper tubing supplied from the tube mill. An assortment of this tubing is carried in stock in the copper shop.
Sheet copper comes from the rolling mill either thoroughly annealed as dead soft sheets dull in color, or of many degrees of hardness and springiness due to the pressure exerted by the rolls and to greater or less annealing after rolling. Planished sheet copper has a bright polished surface as a result of rolling without subsequent annealing.
Fig. 245. - Bench Shears.
The stock of material in the copper shop also includes more or less sheet brass of different thicknesses, degrees of hardness due to rolling, and of a composition suitable for shaping by bending and hammering cold.