ANSI/ ASME INTERNAL Screw Thread Size Chart. All units are in inches. Unified Screw Threads per. ANSI/ASME B1.1-1989 (R2001), R2001) Nomenclature, are used. Acceptability criteria are described in ANSI/ASME B1.3M-1992 (R2001). Note: This screw chart is not comprehensive of all available standard threads as provided by the standard.

G Thread Connection Cylindrical Pipe Thread Connection According to ISO 228/1 (other common descriptions are BSP, R) Male: ie. G 1/4" (ISO 1179): ie. G 1/4" Male Thread G 1/8" G 1/4" G 3/8" G 1/2" G 3/4" Thread G 1/8" G 1/4" G 3/8" G 1/2" G 3/4" 9.6 13.0 16.5 20.8 26.3 8.75 11.8 15.25 19.0 24.5: 8.0 10.0 10.0 12.0 12.0 7.4 11.0 11

Thread Form r = Basic Radius = * 137329 p h = Basic Depth of Thread = *640327 p p = Pitch = 1/t.p.i. (Threads per Inch) ISO 228, DIN 259, BS2779, JIS B0202 In Japan this thread is known as (PF) Use prefix G for parallel thread. Example: G1/2 11 /

Whitworth's new standard specified a 55° thread angle and a thread depth of 0.640327p and a radius of 0.137329p. Where p is the pitch. The thread pitch increases with the diameter in steps specified on a chart. The Whitworth thread system was later to be adopted as a British Standard to become British Standard Whitworth (BSW).

Size x Pitch. TPI. External ISO Pipe Thread Design Chart. Class. Major Dia. Pitch Dia. Minor Dia. Max. Min. Max. Min. Max. Min. G 1/16. G7.723 x 0.907.

Parallel (G) threads are used where the seal is made on a mating face, like inside a cast iron radiator with the aid of a gasket. Tapered fittings achieve a 

threads: BSP parallel: G followed by the designation BSP taper: R followed by the designation Metric Thread Code Metric Thread Code Metric Thread Code M3x0.5 09 M12x1.25 66 M22x1.5 82 M5x0.8 19 M12x1.5 67 M24x1.5 83 M6x1 52 M13x1.25 68 M27x1.5 85 M7x1 55 M14x1.25 70 M30x2 88 M8x1 56 M14x1.5 71 M33x1.5 90

British Standard Pipe (BSP) has been use as standard in plum and pipe fittings. There are two types of BSP Thread available. Parallel threads & Taper 

Fastener and Screw / Bolt Design, Formula and Calculations External Pipe Threads per. ISO 228-1, Pipe threads where pressure-tight joints are not made by the threads. These pipe threads are also known as Whitworth pipe threads. Where: D = Major Dia.internal thread D 1 = Minor Dia.internal thread D 2 = Pitch diameter internal thread

The table below summarises BSP sizes to help with general identification. Major diameter is slightly less than the actual outside diameter of the threads.

British Standard Pipe BSP thread chart, BSP thread chart showing TPI and drill sizes. BSPP / BSPT B RITISH S TANDARD P IPE P ARALLEL / B RITISH S TANDARD P IPE T APER