Separable sockets are used to provide pressure tight connections where required. They also offer the advantage of allowing a thermometer to be removed from a system without disturbance. The thermometer is inserted and tightened to the separable socket by means of a threaded swivel nut coupling. Quick response to temperature change is assured since the stem and socket are precision tapered, providing a metal to metal contact at the sensitive bulb section. To withstand severe corrosive conditions, sockets machined of special materials are available. Pipe threads on separable sockets can be located at different points on the stem. Thread location determines the insertion length and the length available for insulation.