Pressure Sensor Fittings: Straight Thread vs Tapered

High pressure process connectionWhen choosing a thread style to mount your pressure transducer or digital pressure gauge, the choices fall between tapered thread (e.g., NPT or BSP) or straight thread (e.g., UNF or SAE).


Tapered threads form a seal by themselves. When tightening the threads to the proper torque, the threads tighten against each other and form a seal.  Often, Teflon® tape or liquid paste pipe sealant is used to help the seal form properly.


Straight threads do not create a seal. Instead, they bear the load of the pressure and strengthen the connection.  A gasket or O-ring is needed for the seal.  On SAE fittings, the connection also has a cone shaped tip and is connected to a mating cone to provide the seal.


With APG pressure sensors, tapered connections are most common under 10K PSI. For anything greater than 10K PSI, we usually use the 9/16”straight thread with a cone.

Let us know if you have any questions about pressure sensor process connections.


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