One of the more frequently asked questions of our sales organization is "What is the difference between a Tek screw and a self-tapping"? It seems like such a silly question, but in the industrial insulation world it actually does matter. Confusion does exist on such a simple question. These screws are used in numerous mechanical insulation projects. Both types of screws are used for securing metal jacketing, aluminum and stainless elbows, along with T-Covers.