API Std 650 - Threaded Roof Nozzles (in)

API Std 650 - Threaded Roof Nozzles (in) [a] Reinforcing plates are not required on nozzles NPS 6 or smaller but may be used if desired.
Nozzle (NPS)	Coupling (NPS)	Diameter of Hole in Roof Plate or Reinforcing Plate \(D_P\)	Outside Diameter of Reinforcing Plate [a] \(D_R\)
3/4	3/4	1 7/16	4
1	1	1 23/32	4 1/2
1 1/2	1 1/2	2 11/32	5
2	2	3	7
3	3	4 1/8	9
4	4	5 11/32	11
6	6	7 17/32	15
8	8	9 7/8	18
10	10	12	22
12	12	14 1/4	24