API 650 open top welded storage tanks equipped with a fixed roof

Impact Requirements for Controlled-rolled or Thermo-mechanical Control Process (TMCP) Plates: Subject to the approval of the Purchaser, controlled-rolled or TMCP plates (material produced by a mechanical- thermal rolling process designed to enhance the notch toughness) may be used where normalized plates are required. API 620 welded storage tanks each used plate, as rolled, shall be Charpy V-notch tested to the requirements of R.2.1.2.

This standard applies only to API 650 tank API 650 open top welded storage 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.

Weld inspection of API 650 open top welded storage tanks, vertical oil tank wall plate: In the welding inspection process of oil tank wall plate, attention should be paid to the defects of thick wall plate, such as incomplete penetration, incomplete root fusion and cracks. If there is a root incomplete penetration defect, it is necessary to open the weld joint with carbon arc air gouging and grinding machine grinding, or even weld through, and then weld again after the defect is removed.