ASTM A216 grade WCA external floating roofs API Std 650 flat-bottom tanks

The water dissolved in the oil will be separated out from the oil stored in the API Std 650 flat-bottom tanks for a long time, and the acidic water layer will appear at the bottom of the API Std 650 flat-bottom tanks for a long time, which will accelerate the corrosion of the API Std 650 flat-bottom tanks and cause the wall thinning and even leakage. With the increase of service life, the API Std 650 flat-bottom tanks must be inspected and cleaned regularly to check the hidden danger.

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.

API 650 "welded storage tanks" API Std 650 flat-bottom tanks is a standard developed and issued by the American Petroleum Institute (API), which specifies the minimum requirements for the design, manufacture, installation and inspection of welded storage tanks.