Plug
Plug is screwed in the internal thread of the access fitting and holds the probe. An isolation system consisting of Primary Packing, Secondary Packing and Packing Retaining Nut is used to maintain the pressure and to avoid fluid leakage. A PTFE pipe plug could be used to protect the internal thread.
Plugs can distinguished in two classes depending on the monitoring device that they have to support:
- Solid plug
- Hollow plug
Solid plug for monitoring devices that do not need any electrical connection with the outside (i.e. Coupon Holder, Injection Probe).
Hollow plug for monitoring devices that need an electrical connection with the outside (i.e. ER Probe, LPR Probe).
As for the Access Fittings, manufacturing characteristics of the plugs descend from process conditions.