The pe fitting are identified based on their connection types and functions:

A. According to Connection Type
Pipe fittings are connected to pipes through various connection methods, all of which have their own advantages.

I. Compression Fittings
Compression fittings are well-suited for metal on metal connections. These are fittings that use compression on a ring, gasket, or ferrule to connect pipes. The compression is usually made by tightening a nut into the fitting over the ferrule and piping, securing and compressing the internal piping. Standard compression fittings don’t need tools to assemble. This makes them convenient and quick and simple to install.

Compression fittings cannot handle really high pressures and are not as flexible as soldered fittings. This means they are not suitable for systems with thermal cycling, vibration, and other aggressive conditions.

Bite-type Fittings
These are compression fittings with a sharp ferrule that “bites” the pipe when compressed and provides a tight seal. Similar to standard compression fittings, bite-type fittings don’t need tools to assemble. However, they create a stronger and higher pressure connection.

Mechanical Grip Fittings
These are two-ferrule assemblies – the front and back ferrule. The back ferrule holds the piping while pressing against the front ferrule. This mechanism spring-loads the front ferrule, creating a seal between the fitting body and piping.

Mechanical grip fittings can be reassembled several times without causing damage to the pipes and piping components. Moreover, these fittings have excellent tolerance to mechanical vibration.

Flare Fittings
Flare fittings are made up of a body with a coned or flared end. They require special flaring tools to attach the pipe inside the coned end, achieving a tight seal. These fittings can endure higher pressures and a wider range of system conditions compared to standard compression fittings.

II. End Fittings
End fittings create specific surfaces for pipe connections.

Clamp Ends
Clamp end fittings allow pipes to clamp to the pipe connection.

Plain Ends
Plain end fittings allows pipe connections through solder, adhesive, welding, and other methods.

III. Flange Fittings
Flange fittings are edges, rims, collars, or ribs with flat surfaces that are perpendicular to the connected pipe. These surfaces are held together through bolts, clamps, brazing, welding, or threading.

IV. Threaded Fittings
Threaded fittings are made of screw threads on their inner and outer surfaces built to allow piping with matching threads. Straight threads refer to threads that create a simple connection with no seal. Meanwhile, tapered threads are threads that create a tight seal for fluids and gases under pressure. Increased seal reliability is possible by adding a seal tape or coating.

Thread sizes are measured and based on the internal of the pipe. Common thread size standards include National Pipe Thread or NPT and British Standard Pipe (BSP). However, there are other standards used depending on the industry and country.