Popular couplings British Standard Pipe (BSP) threads, also known as Whitworth threads.
The BSPP (parallel) male will mate with a BSPP (parallel) female or a female port. The BSPP male has straight threads and a 30° seat. The BSPP female has straight threads and a 30° seat.
The female swivel BSPP has a tapered nose which seals on the cone seat of the male.
The BSPP (parallel) connector is similar to, but not interchangeable with, the NPSM connector. The thread pitch is different in most sizes, and the thread angle is 55° instead of the 60° angle found on NPSM threads.
The BSPT (tapered) male will mate with a BSPT (tapered) female, or a BSPP (parallel) female.
The BSPT male has tapered threads. When mating with either the BSPT (tapered) female or the BSPP (parallel) female port, the seal is made on the threads accomplished by thread distortion. A thread sealant is recommended.
The BSPT connector is similar to, but not interchangeable with, the NPT connector. The thread pitch is different in most cases, and the thread angle is 55° instead of the 60° angle found on NPT threads.
This is a dryseal thread, the National pipe tapered thread for fuels. This is used for both male and female ends. This connection is still widely used in fluid power systems, even through itiIs not recommended by the National Fluid Power Association (N.F.P.A.) for use in hydraulic applications.
The NPTF male will mate with the NPTF, NPSF or NPSM female.
The NPTF male has tapered threads and a 30° inverted seat. The NPTF female has tapered threads and no seat. The seal takes piace by deformation of the threads. The NPSM female has straight threads and a 30° inverted seat. The seal takes piace on the 30° seat.
The NPTF connector is similar to, but not interchangeable with, the BSPT connector. The thread pitch is different in most sizes. Also, the thread angle is 60° instead of the 55° angle found on BSPT threads.
The NPSM female has straight threads and a 30° inverted seat.
This is used on the female swivel nut of iron pipe swivel adapters.
The leak-resistant joint is not made by the sealing fit of threads, but by a tapered seat in the coupling end. This connection is sometimes used in fluid power systems.
The DIN 24° cone male will mate with any of the three females listed: Female 24° cone with O-Ring, Female metric tube, Female Universal or 60° cone.The male has a 24° seat, straight metric threads, and a recessed counterbore with matches the tube O.D. used with it.The mating female may be a 24° cone with O-ring (DKO type), a metric tube fitting or a universal 24° or 60° cone. There is a light and heavy series DIN coupling. Proper identification is made by measuring both the thread size and the tube O.D. (the heavy series has a smaller tube O.D. than the light, but has a thicker wall section).
The Society of Automotive Engineers (SAE) specifies a 37° angle flare or seat be used with high pressure hydraulic tubing. These are commonly called JIC couplings. The JIC 37° flare male will mate with a JIC female only. The JIC male has straight threads and a 37° flare seat. The JIC female has straight threads and a 37° flare seat. The seal is made on the 37° flare seat by establishing a line contact between the male flare and the female cone seat. The threads hold the connection mechanically.
A seal is made when the O-Ring in the male contacts the flat face on the female. Couplings are intended for hydraulic systems where elastomeric seals are acceptable to overcome leakage and leak resistance is crucial. This connection offers the very best leakage control available today. The male connector has a straight thread and a machined flat face. The female has a straight thread and a machined flat face. The seal takes place by compressing the O-Ring onto the flat face of the female, similar to the split fiange type fitting. The threads hoid the connection mechanically.
SAE O-Ring Boss (ORB) threaded fittings are recommended by the N.F.P.A. for leakage control in medium and high pressure applications. While JIC 37° fittings have the same straight threads, JIC fittings create a metal-to-metal fitting, and SAE ORB fittings are sealed on an o-ring. O-ring seals are the best type of seals in regards to leakage because the seal takes place at the o-ring and not the threads.