Fitting Systems
7. FITTING SYSTEMS
There are two basic styles of fitting for corrosion probes, fixed and retrievable under pressure. Where fixed probes are used, the plant or process normally requires a shutdown or depressurization period in order for the probes to be removed from the system. Retrievable/Retractable probes are designed to be installed and removed from locations whilst plant is under operating conditions, and without shutdown.
7.1 FIXED FITTINGS
Probes with fixed fittings are coupled directly into plant usually via a female half coupling welded onto the plant. Typical specifications for fitting are NPT which are capable of working at pressures of up to 1500psi.
Adjustable coupling variations of this style are available to permit probes to be positioned for optimal insertion. Pressure ratings as per standard swage lock fittings are available.
For high pressure fixed applications it is common for flanged probes to be used.
7.2 RETRIEVABLE FITTINGS
There are several operating systems which permit probes to be installed and retrieved during normal plant operation. The two most common are the 2″ High Pressure Access System and the 1″ Low Pressure Access System (5/8″ diameter). These are usually referred to as the Retrievable and Retractable systems respectively.
The 2″ High Pressure System enables probe insertion and withdrawal at pressures up to 6000 psi using special probe carriers (2″ access fittings) and retrieval tools.
The 1″ Low Pressure System is based on a packing gland concept and insertion is accomplished via port valve. The system is limited capable of pressures up to 1500 psi.
7.3 SPECIAL APPLICATIONS
There are many instances where standard fittings are not suitable for mounting probes to meet the monitoring requirement. In these cases customization is often possible. Cormon has an extensive design capability in this area.
