Because this kind of replacement is costly in both downtime and new sensors, if a sensor fails, that particular temperature measurement is lost until the next maintenance schedule. A facility will not shutdown a boiler earlier than originally scheduled even if more than 50% of the sensors fail before the maintenance schedule, unless there is a critical safety issue requiring shutdown.
Thermocouples are long, typically about 20 to 40 feet long. They have a small metal pad welded to the tip of the sensors sheath with the weld pads tack welded to the surface of the Protection Tube (pipe) inside the high temperature area making them typically expensive to replace.
Moore Industries has a simple and economical solution to this complicated process: The WORM Flexible Temperature Sensor. It lets you replace the sensor without removing the Protection Tube or disassembling the thermowell by just replacing the broken sensor. The High Temperature WORM is a flexible sensor for thermowell temperature assemblies that is available in standard sensor types including 100 and 1000 ohm platinum, nickel and copper RTDs, and J-, K-, T-, E- type thermocouples with step response times 13% faster than standard sensors. The WORM comes in a universal length so there’s no need to stock an expensive array of different sensor lengths. With a quick measurement and a simple trim-to-length, the WORM handles nearly every thermowell assembly.For boiler tube applications, the WORM ships with a hollow protection tube that includes a weld pad with a thermocouple WORM Sensor that enables sensor replacement from outside of a boiler. The tube is hollow and allows a flexible Worm Sensor to slide down inside the Protection Tube from outside the boiler. This allows the customer to replace a sensor, if it should fail, anytime while the furnace is still up and running.