BlastOne

Threaded Fitting Sizes and Dimensions

Calculate the correct thread pitch and nominal bore size.

thread pitch calculation

If there are six whole threads within the N Distance and if N =- 3/4" then the calculation is 6 divided by 3/4 which equals 8 TPI (TPI = Thread per Inch)

nominal bore size guide

Example: If the above fitting measurement at X is 1-7/8" (47.6mm), then the NB Size is 1-1/2" (38mm)

 

Nominal Bore(NB)
Pipe Size
Approx. Measurement of
OutsideDiameter of
MALE THREAD
Threads
per inch
Thread Pitch
(Distance between each thread)

thread pitch
Imperial Metric Imperial Metric (TPI) (mm) (inch)
1/8" BSP (6mm) 9.5mm (3/8") 28 0.91 0.036
1/8" NPT (6mm) 9.5mm (3/8") 27 0.94 0.037
1/4" BSP (8mm) 12.7mm (1/2") 19 1.34 0.053
1/4" NPT (8mm) 12.7mm (1/2") 18 1.41 0.056
3/8" BSP (10mm) 15.9mm (5/8") 19 1.34 0.053
3/8" NPT (10mm) 15.9mm (5/8") 18 1.41 0.056
1/2" BSP (13mm) 20.7mm (13/16") 14 1.81 0.071
1/2" NPT (13mm) 20.7mm (13/16") 14 1.81 0.071
3/4" BSP (20mm) 26.2mm (1-1/32") 14 1.81 0.071
3/4" NPT (20mm) 26.2mm (1-1/32") 14 1.81 0.071
1" BSP (25mm) 31.8mm (1-1/4") 11 2.31 0.091
1" NPT (25mm) 31.8mm (1-1/4") 11-1/2 2.21 0.087
1-1/4" BSP (32mm) 41.3mm (1-5/8") 11 2.31 0.091
1-1/4" NPT (32mm) 41.3mm (1-5/8") 11-1/2 2.21 0.087
1-1/2" BSP (38mm) 47.6mm (1-7/8") 11 2.31 0.091
1-1/2" NPT (38mm) 47.6mm (1-7/8") 11-1/2 2.21 0.087
2" BSP (50mm) 58.7mm (2-5/16") 11 2.31 0.091
2" NPT (50mm) 58.7mm (2-5/16") 11-1/2 2.21 0.087
2-1/2" BSP (65mm) 73mm (2-7/8") 11 2.31 0.091
2-1/2" NPT (65mm) 73mm (2-7/8") 8 3.18 0.125
3" BSP (80mm) 88mm (3-15/32") 11 2.31 0.091
3" NPT (80mm) 88mm (3-15/32") 8 3.18 0.125
4" BSP (100mm) 113mm (4-15/32") 11 2.31 0.091
4" NPT (100mm) 113mm (4-15/32") 8 3.18 0.125
6" BSP (150mm) 163mm (6-15/32") 11 2.31 0.091
6" NPT (150mm) 163mm (6-15/32") 8 3.18 0.125