Temperature sensors or indicating type temperature gauges are not directly inserted into the process pipe, unless these are used to measure the outside temperature of process pipe, instead, these are used with thermowells. By using thermowells, sensors and gauges will not interfere with the process line operation, and the users are able to perform the maintenance procedure of the process line more easily. These thermowells can be used in a high steam line or Vapor line. These are directly welded onto the socket or pipe so can be a semipermanent. Therefore, the user must carefully decide its material and specification before welding process is performed.