Whitworth thread for pipe installations: The Whitworth thread named after the British engineer J. Whitworth (1803-1887), also known as British Standard Pipe (BSP) or British Standard Pipe Taper (BSPT), were originally thread forms for pipe fittings. They are still used for pipe installations in Europe today. They are therefore also known as pipe threads. In contrast to the metric ISO thread, the pitch is specified as the number of turns per inch (25.4mm). Whitworth threads have a steeper flank than metric threads: flank angle 55°, compared to 60° for metric threads.
A distinction is made between tapered and cylindrical versions of Whitworth threads ( Here you can find more information about the pipe thread types)
Tapered threads (BSPT)
Tapered threads (BSPT) according to DIN EN 10226-1 (formerly DIN 2999) are designated as metallic sealing (R). The reason is that the nominal diameter of the tapered thread corresponds to that of the counter thread after a few turns. When tightened further, the threads jam into each other and thus have a metallic sealing effect.
Water installations (cold and hot water) are traditionally carried out with metallically sealing Whitworth pipe threads. Common sizes are R1⁄4″, R3⁄8″, R1⁄2″, R3⁄4″, R1″, R11⁄4″, R11⁄2″.
Cylindrical threads (G)
Cylindrical threads (G) according to DIN ISO 228 are not self-sealing.
Depending on the air flow rate, different sizes up to G3″ are used.
Dipping bottle valve:
In Europe, the (internal) thread G5/8″ is used for diving bottle valves for compressed air.
Liquid coolers for computer water coolers and their water/air heat exchangers use both tapered and cylindrical Whitworth pipe threads. In Germany, the G1/4″ and G1/8″ threads are the most common, including for computer cooling systems.