API Std 650 - Roof Manholes (mm)
- American Petroleum Institute (API)
- API Std 650 - Standard for Welded Tanks for Oil Storage
| API Std 650 - Roof Manholes (mm)
 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Size of Manhole (NPS) | Diameter of Neck [a] 
 
 \(ID\) | Diameter of Cover Plate 
 \(D_C\) | Diameter of Bolt Circle | Number of Bolts 
 
 \(D_B\) | Diameter of Gasket Inside | Diameter of Gasket Outside | Diameter of Hole in Roof Plate or Reinforcing Plate \(D_P\) | Outside Diameter of Reinforcing Plate 
 | 
| 500 | 500 | 650 | 590 | 16 | 500 | 650 | 515 | 1050 | 
| 600 | 600 | 750 | 690 | 20 | 600 | 750 | 615 | 1150 | 

