Choosing a port and a matching the right stud fitting can be confusing. While there are several popular types of threaded ports, such as metric, BSP, SAE and NPT. There are many different sealing methods for the mating male threaded connections. This post should clear up the confusion by explaining the differences in these connections.
Metric Thread Port
There are two popular metric thread ports, ISO 6149-1 Port and DIN 3852-1 / ISO 9974-1 Port.
ISO 6149-1 Metric Port:
This one has a special area near the top of the threads where an O-ring fits. Think of an O-ring as a small rubber ring that helps prevent leaks.
DIN 3852-1 / ISO 9974-1 Metric Port:
This style is different because the threads go all the way to the top of the port, with no special area for an O-ring.
BSP Thread Port
BSP contains two forms, BSPP is a BSP parallel thread, and BSPT is a BSP taper thread.
BSPP Thread Port:
There are main three types of seal methords for BSPP stud fittings and BSPP thread port:
BSPP male with O-ring and retaining ring, BSPP male with bonded seal/dowty seal, and BSPP male with captive seal/ED seal.
Image from RYCO
BSPT Thread Port:
There are main two types of seal methords for BSPT male fittings and BSPT thread port.
BSPT male threads seal against threads of fixed BSPT female. BSPT male threads seal aginst threads of BSPT female thread port. The both of Contact is made on the flanks of the threads.
Image from RYCO
NPT Thread Port
NPT means national pipe thread, which contains two forms, one is national pipe taper thread, another is national pipe straight thread.
There are two types of seal methords for NPT threads.
There are main two types of seal methords for BSPT male fittings and BSPT thread port. NPT male threads seal against threads of fixed NPT female. NPT male threads seal with NPSM female thread by 30° seal cone/chamfer.
Image from RYCO
SAE Thread Port
SAE O-ring Boss ports (ORB) provide a seal by trapping the fitting’s O-ring inside a port cavity. When a fitting is installed into the port, the O-ring is trapped between the fitting body hex or washer and port cavity.
Straight fittings include a hex, and sometimes an additional cylindrical shoulder below the hex and above the threads, to trap the O-ring in the port cavity. Elbow and Tee fittings require a backup washer and a locknut above the O-ring on the threaded stud to permit a 360° orientation of the fitting around the port.
Hydraxio is a leading manufacturer and supplier of stainless steel hydraulic fittings and adapters. Metric, BSPP, BSPT, NPT, NPS, SAE threads are all available. Please contact us for more details.
