Thermometrics manufactures a full line of standard and custom weld pad RTD's. The weld pad (tube skin) termination allows a temperature sensor to be welded directly onto piping or other metal surfaces to sense the surface temperature. Weld pads are most commonly used in fired heater tubes, refinery heater tubes, boilers and furnaces in refineries, and industrial boilers. However, they can be used in virtually any application requiring surface temperature measurement - See more at: http://www.thermometricscorp.com/welpadrtdsen.html#sthash.7PMepRMC.dpuf