1/4 BSP Thread characteristics

What is a 1/4 BSP thread?

The 1/4 BSP (British Standard Pipe) thread is one of the most commonly used inch threads in power hydraulics and pneumatics. The “BSP” designation indicates the British standard, based on inches, and the number “1/4” refers to the nominal flow diameter in inches. This thread occurs in two versions: BSPP (parallel) and BSPT (tapered), which allows for wide application in various types of pipe connections and hydraulic fittings.

Characteristics of 1/4 BSP thread

The 1/4 BSP thread has 19 threads per inch (19 TPI), which corresponds to a precise, dense thread pitch. The outer diameter is approx. 13.1 mm, while the inner diameter – approx. 11.9 mm. The 1 4 BSP thread is characterized by very good sealing, especially in connections with sealing rings or when using Teflon tape in tapered versions. Due to its versatility, it is a size often found in systems with medium flow and moderate operating pressure.

Application of 1/4 BSP thread

1 4 BSP thread is used in many elements of hydraulic and pneumatic installations – including among others in:

• quick couplings hydraulic and pneumatic,

• valves, pressure gauges and pressure reducers,

• flexible and metal hoses,

• adapters, plugs and pipe fittings.

Due to its small size and high manufacturing precision, this thread is often used in industrial machines, lubrication systems, laboratory equipment and in compressed air installations.

Components with 1/4 BSP thread in the Hydron store?

In the offer of Hydron, high-quality fittings, adapters, ends and valves with 1 4 BSPthread, made of durable materials such as galvanized steel, stainless steel or brass are available. These products provide full leak-tightness and long-term corrosion resistance, which guarantees reliability even in demanding industrial conditions. Hydron also offers professional technical advice and assistance in choosing the right components.

Types of 1/4 BSP thread – BSPP and BSPT

The 1/4 BSP thread occurs in two basic varieties, which are not interchangeable without proper assembly knowledge.

BSPP 1/4 – cylindrical thread

The BSPP version has a straight (cylindrical) thread. The thread itself does not provide leak-tightness, so the connection is sealed with:

• a metal-rubber washer,

• an o-ring,

• a flat seal.

This type of thread is used very often in pressure gauges and hydraulic fittings.

BSPT 1/4 – tapered thread

The BSPT version is a tapered thread, which seals on the threads. In practice it requires:

• PTFE tape,

• sealing paste,

• thread glue.

Most commonly found in pneumatics and in screw-in connections without a seal seat.

1/4 BSP thread dimensions:

• Thread type: BSP (British Standard Pipe)

• Type: parallel (BSPP) or tapered (BSPT)

• Outer diameter: 1/4 bsp thread is approx. 13.1 mm

• Number of threads: 19 TPI

• Thread pitch: approx. 1.34 mm

• Thread angle: 55°

• Sealing: mechanical or with a ring / PTFE tape

BSP thread table