News & Events

» Tapered pipe thread hydraulic connectors – BSPT and NPTF

Tapered pipe thread hydraulic connectors have an outside diameter that is cut on a cone.

This results in sides that are not parallel.

Two common types of tapered thread connectors are BSPT and NPTF.

BSPT British Standard Pipe Taper

Country of origin: Britain
Thread angle: 55 degrees (Whitworth)
Seat angle: 30 degrees

BSPT is a tapered thread. This means that the outside diameter of the thread is cut on a cone.

BSPT Thread - Not Parallel

The sides are not parallel.

The taper angle is a rise of 3/4″ for every 12″ in length.

This is approximately 1 degree, 47 minutes.

BSPT Thread - Angles

Male BSPT threads mate with female BSPT threads in adaptors.

BSPT female threads are also used in port applications.

BSPT Thread - Male-Female

As BSPT ports seal directly on the thread, the only machining required is drilling the hole and tapping the thread.

BSPT threads can also be used as a machined seat connector.

BSPT Thread - Nut

The thread used in the female swivel is parallel, BSPP.

This is so that the connector bottoms out onto the sealing face.

The female swivel is made as a two part assembly.

The majority of these connections use a crimped nut.

BSPT Thread - Nut

Larger sizes use a wire locked nut.

This increases the pressure capability of the connection.

BSPT Thread - Wire Lock

NPTF National Pipe Taper (Fuel)

Country of origin: USA
Thread angle: 60 degrees (ANSI)
Seat angle: 30 degrees

NPT is the standard American pipe thread.

NPTF is a derivative used in hydraulics. The “F” means that it is modified for fuel use.

NPTF Thread Diagram

NPTF threads have controlled truncation which means that the roots and crests of NPT threads fit more closely with their mating parts than most other threads.

For this reason, NPT threads feel “sharper” than their BSPT counterparts.

NPTF Thread Diagram

NPT threads are also used in port applications.

NPT port threads will look identical to BSPT ports, but it is important that NPT threads are not interchanged with BSP threads.

NPTF Thread Diagram

When NPT threads are used as machined seat fittings, a parallel female thread is used.

This is to ensure that the threads bottom out on the machined seat.

This thread is called NPSM, National Pipe, Straight Mechanical.

All RYCO NPT parts are extemally grooved or notched so that they can be easily identified.

NPTF Thread Nut

A notch results when a groove is machined in a hex.

Larger sizes use a wire locked nut.

NPTF Thread Wire Lock

This increases the pressure capability of the connection.

NPT threads are the preferred thread for very high pressure systems such as jacking systems.

Working Pressure 700 Bar – 10,000

Pipe threads are mechanically very strong because the thread length is generally twice as long as that of an equivalent sized thread such as JIC.

Want more information?

For a quick introduction to the specific types hydraulic connectors check out our series on hydraulic connector thread forms.

Make sure you select the right hydraulic hose for your next project. Download our 15 Keys To Selecting The Right Hose guide today.