# API Std 650 - Threaded Roof Nozzles (in)

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 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