Pipe Thread data sheet


External (pipe) Basic Thread Dimensions

For interpertations of the terms scroll down to the drawings below the table

Property Inch mm
Nominal Pipe Size (Ø) 8" ...
Pipe Outside Diameter (D) 8.625 219.075
Pitch (TPI) (P) 8.000 203.2
Pitch (Distance) (P) 0.125 3.175
Thread Tapper Angle (ß) 1.7893° 1.7893°
Thread V half Angle (α) 30° 30°
Height of sharp V (H) 0.108253 2.75
Thread height (h) 0.1 2.54
Pitch Diameter at the Pipe's end (E0) 8.43359 214.213
Minor Diameter at the Pipe's end (K0) 8.3336 211.673
Hand-Tight Engagement Length (L1) 1.063 27
Pitch Diameter at L1 plane (E1) 8.50003 215.901
Length of Last Complete Thread (L5) 1.4625 37.148
Pitch Diameter at L5 plane (E5) 8.525 216.535
Length of Last usefull Thread (L2) 1.7125 43.498
Pitch Diameter at L2 plane (E2) 8.54062 216.932
Overall Thread Length (L4) 2.1462 54.513
Length of Vanish threads (V) 0.4338 11.019

8-8 NPT - External (pipe) Drawing

Overview Drawing

Profile Drawing

8-8 NPT - Internal (Fitting) Basic Thread Dimensions

For interpertations of the terms scroll down to the drawings below the table

Property Inch mm
Nominal Pipe Size (Ø) 8" ...
Pipe Outside Diameter (D) 8.625 219.075
Pitch (TPI) (P) 8.000 203.2
Pitch (Distance) (P) 0.125 3.175
Thread Tapper Angle (ß) 1.7893° 1.7893°
Thread V half Angle (α) 30° 30°
Height of sharp V (H) 0.108253 2.75
Thread height (h) 0.1 2.54
Pitch Diameter at the fitting's end (E1) 8.50003 215.901
Length of Hand-Tight Engagemen (L1) 1.063 27

Length of Wrenching Allowance (L3)

0.25 6.35
Pitch Diameter at L3 plane (E3) 8.41797 213.816
Tap Drill Size (T) N/A N/A

8-8 NPT - Internal (Fitting) Drawing

Overview Drawing

Profile Drawing

8-8 NPT - Tolerances

Property Minimum Maximum
Thread Height (h) 0.09275" (2.356 mm) 0.1" (2.54 mm)
L1 gage Tolerance (+/- 1 Turn) (L1) ... 0.125" (3.175 mm)
Thread Truncation (f) 0.0041" (0.104 mm) 0.0078" (0.198 mm)
Tapper angle Variation (ß) 1.641" ( ) 2.089" ( )
Thead V Half Angle (+/-) (α) ... 0.75" ( )
Thread Height (h) " (0 mm) " (0 mm)
L1 gage Tolerance (+/- 1 Turn) (L1) " ( ) " ( )
Thread Truncation (f) " (0 mm) " (0 mm)
Tapper angle Variation (ß) " ( ) " ( )
Thead V Half Angle (+/-) (α) " ( ) " ( )
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