Piping and plumbing fitting#Union

A screw is used to quickly and securely linking of individual parts, such as hoses or pipes through two threaded pieces. The components to be connected even do not need to be rotated relative to each other. For pipe fittings connections are used up to DN 40 ( 1 1/ 2 inches) and nominal pressures of up to several 100 bar. In contrast to a flange of a screw for small nominal diameters of pipe is easier to manufacture, since consuming welding work is required.

In the field of hydraulics cutting ring fittings are used with Nut and Ring in Europe today mostly. Due to the increased use of American and Japanese construction equipment put in Europe increasingly glands by, where the " cutting ring principle " be invisible altogether. Thread connections are in inches (BSP or JIC ) and are provided with 60 ° (BSP ) or 74 ° ( JIC ) sealing cone.

When water installations are, depending on pipe material and execution compression fittings, Rotgussverschraubungen and Dutch and Tempergussverschraubungen used.

In the food industry pipe fittings are used with "milk pipe thread " according to DIN 11851. These threads are easy to clean special thread to DIN 405

In electrical installation fittings are used to strain relief cable and waterproof in junction boxes, or similar distribution introduce. Until 2004, such bolting had the PG thread. Nowadays, they are manufactured with metric thread.

In refrigeration flared metal pipes are bolted to blunt cone.