All you need to know about tube fittings
A tube, like a pipe, is a hollow structure that provides an enclosed conduit for fluids to move. In the case of tubing, it is often made of rolled or extruded metal (although plastic is a typical tube material for many industrial applications). This section discusses some of the more prevalent methods for connecting tubes (and joining tube ends to equipment such as pressure instruments).
One key distinction between tube and pipe is that tube is never threaded at the end to establish a connection. Instead, a tube fitting must be used to connect one segment of the tube to another, or a section of pipe, or a piece of equipment (such as an instrument). Tubes are thin-walled constructions, as opposed to pipes, which are thick-walled by nature. A typical tube’s wall thickness is simply too thin to sustain threads.
For small-diameter applications, tubes are often preferred over pipes. The box is the favored choice for connecting instruments to process lines due to the ability of competent employees to easily cut and bend tubes using simple hand tools and the ability to repeatedly break and re-make tube connections without affecting the integrity of the seals. The box is usually an impulse tube or impulse line when utilized as a connecting unit between an instrument and a process pipe or vessel.
Fitting construction and material standards vary depending on the application; consulting the fitting supplier is an excellent way to optimize component choices. However, the majority of tube fittings are associated with either hydraulic or pneumatic systems. Therefore, the fundamental system type is the initial step in identifying which fittings are appropriate for the application.
- The transmission of liquid fluids such as water and other chemical solvents is an everyday use for hydraulics. Therefore, hydraulic fittings must have seals that prevent liquid leakage and are often resistant to rust or further chemical deterioration.
- Gases are transferred in pneumatic applications. Therefore, pneumatic fittings must have extremely tight seals to avoid gas leakage and be chemically resistant.
- Tube fittings are also used in other areas such as structural design. Because they do not transmit fluids, these fittings must have excellent physical integrity but do not often require sealing.
Shop with us for tube fittings. We are your number #1 expert in hose and seals.