What Size Is Your Tri-Clamp Fitting?May 27, 2016
When the Tri-Clamp sanitary union was invented, the original sizes were 1-½” through 4”. Each size had its own unique clamp and gasket. After the initial introduction of the Tri-Clamp connection, it was decided that a 1” Tri-Clamp union should be added. Instead of designing a new clamp and gasket, they decided to use the 1-½” clamp along with the same profile gasket as the 1-½” but having a smaller hole in the center.
Like all sanitary fittings, Tri-Clamp fittings are measured in tube OD. The outside diameter of the tubing itself is the determiner for gasket size, not the face of the Tri-Clamp ferrule. If you put a 1” and 1-½” Tri-Clamp elbow side by the, you will find that the outside diameters of the clamp ferrule faces will both measure 1.984”. However, the OD of the tube sections will measure 1” and 1 ½” respectively.
Both the 1″ and 1-½” Tri-Clamp Fittings use the same clamp, but use different gaskets which are not interchangeable. Thus, 1″ and 1-½” Tri-Clamp Gaskets have the Same OD but Different IDs.
Another Instance of a Common Clamp Size Exists with the ½” and ¾” Tri-Clamp Fittings
The ½” and ¾” Tri-Clamp fittings also use the same clamp but different gaskets [as illustrated below]. You can get a ½” gasket to clamp into a ¾” Tri-Clamp connection and vice versa. To determine the fitting size measure the OD of the tube, not the ferrule flange OD.