Thread Chart For Hydraulic Fittings

The Society of Automotive Engineers (SAE) utilizes straight threads (UN/UNF) with a 45° flare seat to form the seal. The threads of both halves mesh together to create a strong mechanical connection. While the SAE 45° Flare connectors and the JIC 37° Flare connectors share identical thread specifications, their seating angles differ.

Note: Most SAE threads (SAE J512) are identical to the JIC 37° flare threads (SAE J514), except for the difference in their seating angles.

SAE O-Ring Boss (ORB) features a straight thread (UN/UNF). The female component has a sealing face and chamfer, while the male component includes an O-ring. When the O-ring is compressed into the opposing chamfer, it forms a seal. The male and female threads mesh to create a solid connection. ORB threads conform to SAE J1926-1 and ISO 11296-1 standards.

O-Ring Face Seal (ORFS) thread is a straight thread (UN/UNF) that complies with the SAE J453 standard. The female connector has a flat surface, while the male connector features an O-ring on its face. The seal is achieved when the O-ring on the male connector compresses against the flat surface of the female connector. An outside nut on the female connector secures the connection.

Flareless tube fittings conform to the SAE J514 standard. These fittings consist of a compression ferrule/sleeve, a female nut, and a fitting body. The seal is formed between the tubing and the female compression sleeve.

British Standard Pipe Parallel (BSPP) threads conform to the ISO 228-1 standard. The BSPP male thread features a 30° seat, and the BSPP female thread has a swivel nut with a matching 30° seat. The seal is created by the contact between the 30° seats of the male and female threads.

British Standard Pipe Tapered (BSPT) threads meet the ISO 7-1 standard and feature a 55-degree angle. The tapered design of BSP threads allows for a more secure fit, making them suitable for high-pressure applications.

BSPT male threads are referred to as R series threads, while BSPT female threads are known as Rc series threads. These threads form a metal-to-metal seal and do not require O-rings, although sealants may sometimes be necessary.

Metric fitting meet DIN 2353/ISO 8434-1 standard, as a compression tube fittings consists of a fitting body, a nut, and a cutting-ring that have straight threads, with the male having a 24° cone.

Japanese Industrial Standard (JIS) features BSPP threads with a 30-degree cone/seat. These standards are established by a group in Japan and are maintained by the Japan Standards Association.

Note: While the 30° seat and BSPP-like thread dimensions differ from the American 37° Flare, the connections are quite similar.