Specifications

Chapter 14: Appendices
Appendix 8: Bolt Thread Dimensions
(12/99) 14-15
Appendix 8: Bolt
Thread Dimensions
The following tables list National Pipe Taper (NPT) dimensions and straight thread
dimensions for hex head bolts.
NPT Dimensions
B
A
1° 47'
Effective Thread
NPT Size Threads
Per Inch
A
(inches)
B
(inches)
1/16 27 0.312 0.261
1/8 27 0.405 0.264
1/4 18 0.540 0.402
3/8 18 0.675 0.408
1/2 14 0.840 0.534
3/4 14 1.050 0.546
1 11 1/2 1.315 0.683
1 1/4 11 1/2 1.660 0.707
Table 14-7: NPT Dimensions