These SS304 stainless steel tri clamp weld ferrules are 100% sanitary and they meet all of the requirements of the sanitary industry. These tri clamp weld ferrules are .5" and are 21.5mm long. ID = 3/8"

DETERMINING TRI CLAMP SIZE

Tri Clamp sizes are determined by the outer diameter of the pipe or tubing, not the outer diameter of the flange or Tri Clamp itself. The flange of a Tri Clamp fitting typically has about a ½” inch greater diameter than the outside diameter of the pipe. This can become especially confusing when the Tri Clamp fitting has no pipe attached to it, as is the case with adapters, For instance, a  is not 1.5" inches in any dimension, but the Tri Clamp end will fit any other 1.5" Tri Clamp fitting. 

If you have any doubts about what size Tri Clamp fittings your project needs, simply measure the outside diameter of the flange (dimension "B" below) and consult the chart below, or feel free to  .