API Std 650 - Threaded Roof Nozzles (mm)

API Std 650 - Threaded Roof Nozzles (mm) [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	36	100
1	1	44	110
1 1/2	1 1/2	60	125
2	2	76	175
3	3	105	225
4	4	135	275
6	6	192	375
8	8	250	450
10	10	305	550
12	12	360	600