BSPP Thread data sheet

Basic Thread Dimensions

* The below values are nomoinal (without tolerances) and are valid for both external and internal threads.

Property mm Inch
Nominal Pipe Size (Ø) 2 1/4" ...
Pitch (TPI) (P) 11 ...
Pitch (Distance) (P) 2.309 0.0909
Thread V half Angle (α) 27.5° 27.5°
Height of sharp V (H) 2.218 0.0873
Thread height (h) 1.479 0.0582
Root/Crest Radius (r) 0.317 0.0125
Major Diameter (D) 65.71 2.587
Pitch Diameter (D2) 64.231 2.5288
Minor Diameter (D1) 62.753 2.4706
Tap Drill Size (Td) -999.0 -39.3307
Thread Family BSPP (G)
Relevant Standards ISO 228-1, ISO 228-2

Tolerances for all Classes


BSPP G 2 1/4 (Internal Thread)

Property Minimum Maximum
Minor Diameter (D1) 62.753 mm (2.4706 ") 63.393 mm (2.4958 ")
Pitch Diameter (D2) 64.231 mm (2.5288 ") 64.448 mm (2.5373 ")

BSPP G 2 1/4-A (External Higher precision)

Property Minimum Maximum
Major Diameter (d) 65.276 mm (2.5699 ") 65.71 mm (2.587 ")
Pitch Diameter (d2) 64.014 mm (2.5202 ") 64.231 mm (2.5288 ")

BSPP G 2 1/4-A (External Low precision

Property Minimum Maximum
Major Diameter (d) 65.276 mm (2.5699 ") 65.71 mm (2.587 ")
Pitch Diameter (d2) 63.797 mm (2.5117 ") 64.231 mm (2.5288 ")

* For More Threadibg Information go to the BSP Thread Calculator

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