Pipe fitting involves fixing the manner in which pipes that carry liquid or gas fit together, or performing basic pipe installation. Because different substances can have drastically different effects on pipes, several different materials are used in pipe fitting to ensure that the pipes can withstand the wear and tear incurred by the material they carry. Materials such as plastic, copper, steel, and iron, as well as clay, lead and aluminum, are all common choices for pipe fitting, depending on the specific application. Pipe fitting plays an important role in industries such as manufacturing and plumbing, where the proper selection, joining, and repair of pipes are essential to other dependent processes. Each type of pipe tubing calls for a pipe fitting, and different fittings exist to accommodate variations in materials and applications.
Copper Tubing and Fittings
Two types of copper tubing are typically used: soft and rigid. Because copper is corrosion-resistant, it’s a common choice for hot and cold water supply applications. Although it can be pricey, soft copper is a relatively easy to work with metal, making it suitable for applications that require bent tubing or unusual configurations. Rigid copper can be made softer through annealing, as can soft copper that has hardened through the drawing process. There are several different kinds of fittings used with copper tubing: flare, sweat, and compression fittings are suitable for soft copper tubing, while elbow fittings must be used with rigid copper.
• Flare Fittings
In order to use a flare connection, the end of the tubing must be reworked into a male fitting. To alter the end of the tubing, a flare tool is used to manipulate the metal into a bell-shape, which is then compressed into a male fitting using a flare nut. The flare nut is what connects the tube to the fitting, creating a tight, leak-resistant juncture. The procedure is a cold-working process, meaning the metal need not be heated, and works well on soft copper as well as soft steel.
• Sweat Fittings
Sweat fittings are easy to use—they simply slide onto the end of a piece of copper tubing. To ensure the fitting stays in place, it is then heat treated with a torch to metal the metal. When the metal sweat fitting cools it bonds to the tubing, creating a secure joint. The process is relatively quick and easy, and is preferred in applications where many tube connections must be made at one time.
• Compression Fittings
Compression fittings use soft rings that slide into place over metal tubing, and are then further pushed into place over the connecting fitting. Because the compression ring is soft, it conforms to the shape of the tubing and fitting, producing a seal. However, compression fittings often call for reworking and tightening and take longer to create than a sweat fitting.
• Elbow Fitting
With hard copper, elbow fittings must be used. Because hard copper cannot be reshaped in its rigid form, a pre-shaped connector must be used to connect it to a fitting. Elbow fittings, resembling the human elbow in form (with two entrances for tubing, each at a 90 degree angle to one another), enable rigid copper tubing to change directions because the tubing cannot be bent. However, rigid copper can be heated, melted, and re-worked into a desired shape without damaging the metal.
