What is a Access Fitting?
Access fittings provide access to systems under full operating pressure up to 500bar. The access fitting is permanently attached to the vessel or pipe, and the service valve and retriever are used to insert or remove the various probes, corrosion coupons or injection equipment.
They are available in different main shapes to meet different installation requirements.. flareweld, buttweld, socketweld, NPT and flanged.
For the installed device, the plug connection is the carrier. Depending on the type of device being used, either a fixed plug or a hollow plug is chosen. The plug is screwed into the body of the access fitting and seals the hole of the fitting to limit line pressure.
Together with the valve, the access fitting body and cover (to protect the male threads) is called an access fitting.
The retrieval tool and service valve are components required for online installation and retrieval of the valve assembly. When the valve is removed during retrieval, the service valve is used to limit line pressure. With only one valve and one retrieval tool, multiple access assemblies can be serviced.
Bio Probe assembly
A = Protective cover
B = Solid plug assembly
C = Access fitting body
D = Bio film probe
E = Pipeline
There is a variety of equipment designed for use with high-pressure access fittings. In general, the following equipment can be installed in process pipelines using standard access fittings..
- Corrosion Coupons
- Linear Polarization Probes
- Thermowells
- Biological Probes
- Electrical Resistance Probes
- Hydrogen Probes
- Erosion Probes
- Sacrificial and Impressed Current Anodes
The following functions can be additionally undertaken with the use of access fitting bodies which incorporate a side-tee.
- Process Sampling
- Chemical Injection
- Sand Monitoring
Typically, access fittings are used in oil and gas extraction. In these types of high-pressure operations, users are reluctant to shut down and pressurize process systems to allow for the removal or installation of corrosion monitoring equipment.