These tubes have an enhanced surface area on the outside. The ends are smooth where they will seal inside the tubesheet but the outside diameter of the tube has what is called a low fin. Actually this is just a shallow spiral similar to a screw thread which is incised around the outside of the tube. This works best when the process on the outside of the tubes does not create fouling so the fins will remain exposed.
Comments
These tubes have an enhanced surface area on the outside. The ends are smooth where they will seal inside the tubesheet but the outside diameter of the tube has what is called a low fin. Actually this is just a shallow spiral similar to a screw thread which is incised around the outside of the tube. This works best when the process on the outside of the tubes does not create fouling so the fins will remain exposed.