Before you can start rolling, you will need to select the right expander for the job. Tube OD, and Wall/BWG will determine the size of the expander. However, there are some other factors to consider, such as tube projection, roll length, reach requirements, space constraints, and whether it’s minimum or average wall tubing.
It’s important to consider if the tube is going to be expanded flush to the tube sheet or if it will have a projection. The most common tube projection for shell and tube heat exchangers is 1/8” from the tube sheet. In situations where all tubes will be rolled to the same projection, an expander with a recess collar should be used. This will accommodate the projection and prevent the tube from being pulled into the expander. The outlet side of surface steam condensers can have varying projections, up to 1X’s the tube diameter in length. In this case a telescoping or full recess collar should be used. If no tube projection is specified, the tube expander will come with a flush collar to expand the tube flush to the tube sheet.
Tube expanders come in two different roll lengths: short and long roll. In order to determine the correct roll length, you will need to know the tube sheet thickness. Choose the roll length that will expand the tube sheet area in the least amount of expansions. If expanding tubes in a double tube sheet, the inner primary tube sheet thickness must be specified so the expander’s rolls can be manufactured to allow for the proper effective expansion length. Whereas, the outer tube sheet would use standard rolls.