Fittings, adapters and threads
Technical reference and selection guides on fittings, adapters and threads.
15 guides
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How is the thread type identified on hydraulic fittings?
To identify a thread, the parallel or tapered form, thread pitch and diameter are examined together. The sealing method of the connection must also be defined separately. The fact that parts screw together for a few tur…
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The difference between BSPP and BSPT connections
BSPP refers to the parallel and BSPT to the tapered pipe thread family; looking the same in nominal size does not mean they have the same sealing method. Thread geometry, thread standard and the actual sealing surface o…
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Comparing NPT and NPTF definitions
NPT and NPTF are not the same thing. NPT is evaluated within the scope of the general-purpose pipe thread standard, and NPTF within the scope of the Dryseal design. Similar size and taper do not prove that the connectio…
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Identifying diameter and pitch on metric connections
A metric thread is defined by diameter and pitch; for example, the numbers in M18×1.5 state the nominal thread diameter and the pitch in millimeters. This information alone does not describe the fitting's seating surfac…
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Reading pitch on UN and UNF threads
In unified inch thread designations such as UN and UNF, the nominal diameter and the number of threads per inch are read together. Recognizing the thread family does not on its own determine whether the fitting is a JIC…
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Sealing surface of JIC flare connections
In a JIC 37° connection, the primary seal is provided by the mating of matching male and female conical metal surfaces; the thread mainly generates the clamping force. A thread that engages does not show that the conica…
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ORFS face seal connections
ORFS is a connection family that seals at the face with an O-ring. The flat face, O-ring groove, mating face and the correct seal work together; a matching thread size alone is not sufficient for a proper assembly.
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Series distinction in metric 24-degree connections
In 24° metric connections, the tube diameter, connection type and L/S series information are required in addition to the thread size. The light and heavy series names are not sufficient for selecting by appearance or fo…
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Distinguishing a BSP thread from a cone seating surface
A BSP thread identifies only the thread family of the connection; it does not on its own explain whether sealing is achieved with a flat seal, an O-ring, a cone seat or on the thread. For the correct fitting, the thread…
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The role of the O-ring in ORB port connections
O-ring boss is a design that seals with an O-ring in a parallel-threaded port connection. Unlike ORFS, sealing occurs in the port area; the port geometry and the seal must both be correct.
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Selecting straight and elbow fittings
The choice between straight and elbow fittings is made according to the layout on the machine and the natural route of the hose. Using an elbow can reduce forced bending; however, pressure loss, access, orientation and …
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Swivel nut fitting vs. rotary swivel joint
A nut that can turn during assembly and a swivel joint designed for continuous rotation during operation are not the same. When the term 'swivel fitting' is used, which movement is permitted must be verified from the ma…
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Checking for restriction in reducers and adapters
A reducer or adapter can resolve a geometric difference between two connections; however, it does not automatically equalize the pressure, material and sealing suitability of different parts. Each added part is evaluate…
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Defining the angular orientation of a hose with two elbows
On a hose with two elbows, the orientation of the ends relative to each other is an order detail as important as the length. If it is not clearly defined from which end and from which viewing direction the angle is meas…
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Selecting fitting material and plating
The material and plating of a fitting should not be selected on the basis of appearance or color. Fluid contact, the external environment, temperature, galvanic interaction and the manufacturer's mechanical limits are e…
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