# API Std 650 - Threaded Roof Nozzles (mm)

Written by Jerry Ratzlaff on . Posted in American Petroleum Institute

## standards

• API Std 650 - Standard for Welded Tanks for Oil Storage

• [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