Tube elbows and tees are the geometry-changing fittings within an instrument tube fitting system, providing direction changes and branch connections that allow tubing runs to be routed around equipment, through panels, and into multiple parallel paths. Like the rest of the twin-ferrule tube fitting family, elbows and tees use the same two-ferrule sealing mechanism at each tube connection — the geometry of the fitting body is different, but the connection technology is identical.
Tube elbows come in 90° and 45° configurations. The 90° elbow is the most common, used wherever a tubing run needs to make a right-angle direction change. The 45° elbow provides a gentler transition, with lower pressure drop and less flow disturbance than the 90° — useful in metering and analytical applications where small pressure changes can affect measurement accuracy. Elbows can have tube connections at both ends (the standard configuration), or one tube end and one threaded end (typically NPT or BSP) — useful for transitioning from tubing into a threaded process equipment port.
Tube tees create a three-way connection for branching tubing runs. The standard tee has all three connections at the same tube size and uses tube fittings at all three ports. Reducing tees step down to a smaller branch at the third port, used where the branch line carries less flow than the main run. Run tees have the branch port threaded for direct connection to a sensor, gauge, or pressure switch — combining the branch and the equipment connection into a single fitting.
Crosses provide four-way connections, used at instrument manifolds where multiple measurement points need to be teed off a single main line. Like tees, crosses can be configured with all-tube connections or with mixed tube and threaded ports.
Materials and pressure ratings match the rest of the tube fitting family. Brass fittings are used for general low-pressure work. Stainless steel fittings are standard for higher pressures, corrosive service, and any process where iron contamination must be avoided. The pressure rating of any fitting is constrained by the tubing it is installed on — the fitting is typically rated higher than the tubing's burst pressure, so the tubing becomes the limiting factor in the assembly.