25ft diameter API standard 650 low-alloy steel tanks

The seal of floating roof API standard 650 low-alloy steel tanks is a device used to reduce the evaporation loss of the storage liquid in the annular space between the tank wall and the outer ring plate of the floating roof. The common sealing forms include mechanical seal, elastic filling seal, lip seal and secondary seal. No matter what kind of seal, the seal must be combined with the floating roof effectively to reduce the evaporation loss of the liquid in the floating roof.

Hydrostatic Test
The API standard 650 low-alloy steel tanks product shall be vented to the atmosphere when it is filled with or emptied of water. During water filling, the elevations of at least four equidistant points at the bottom of the tank shell and on top of the ringwall or slab shall be checked. Differential settlement, or uniform settlement of substantial magnitude, requires an immediate stop to water filling. Any further filling with water will depend on an evaluation of the measured settlement.

This standard applies only to API 650 tank API standard 650 low-alloy steel tanks whose entire bottom is uniformly supported and to API 650 tank in non-refrigerated service that have a maximum design temperature of 93°C (200 °F) or less.