The highest design temperature of API standard 650 liquid-storage tanks

The main reason of "small breathing" loss of API standard 650 liquid-storage tanks is the change of atmospheric temperature. When the temperature rises with the increase of solar radiation from dawn, the temperature of oil in the API standard 650 liquid-storage tanks also changes, resulting in the acceleration of evaporation speed and the increase of evaporation pressure. When the pressure exceeds the positive pressure rating of the breathing valve, the oil-gas mixture in the API standard 650 liquid-storage tanks is discharged into the atmosphere through the breathing valve, which is the "exhalation" process of the oil tank.

Charpy V-notch specimens shall be taken from the weld metal and from the heat-affected zone of the welding procedure qualification test plates or from duplicate test plates.
Weld metal impact specimens shall be taken across the weld with the notch in the API 620 oil tank material weld metal. The specimen shall be oriented so that the notch is normal to the surface of the material. One face of the specimen shall be substantially parallel to and within 1/16 in. of the surface.

The outer FRP of API 650 oil tank will not produce electrolytic corrosion with groundwater and brine. The outer FRP will not corrode with gasoline, diesel oil and leaded gasoline API standard 650 liquid-storage tanks. The leakage detector can monitor the whole process 24 hours to eliminate the potential pollution. The leakage detection system is convenient for the inspection and maintenance of API 650 oil tank, and protects the original ecological environment of soil and groundwater.