API Std 650 unanchored flat-bottom tank sheel openings

Service Conditions and Hydrogen-induced Cracking
When the service conditions might include the presence of hydrogen sulfide or other conditions that may promote hydrogen-induced cracking effects, particularly near the bottom of the API Std 650 unanchored flat-bottom tank shell at the shell-to-bottom connections, care shall be taken to ensure that the materials and details of construction of the tank are adequate to resist hydrogen- induced cracking. The Purchaser shall consider restricting the sulphur content of the material to be stored through thickness testing of the steel, laboratory surveillance tests, and the use of internal tank coatings to reduce the possibility of hydrogen-induced cracking.

The seismic effects on the tank wall of API 650 oil storage tank include the inertia moment generated by the weight of the API Std 650 unanchored flat-bottom tank tank and the hydrodynamic pressure of the reservoir, which can be divided into short period pulse pressure and long period fluid slopping convective pressure.

The elastic filling and sealing of floating roof API Std 650 unanchored flat-bottom tank is to fill the elastic and changeable objects in the sealed envelope, and the sealing purpose depends on the compression deformation of the filler. This kind of sealing effect is good, the requirement of the geometry of tank wall is not too high, and the adaptability is strong. However, the elastic filling and sealing has poor wear resistance and is easy to deform and damage in long-term use.