How to test roof seams of API Std 650 ground supported liquid storage tanks

Some defects may be found after the regular safety inspection for the API Std 650 ground supported liquid storage tanks. The common API Std 650 ground supported liquid storage tanks defects are: Tank cracks, tank welding defects. The cracks on the base metal, surface and near surface of the tank wall shall be eliminated by grinding with circular arc, and then magnetic particle inspection or re inspection shall be carried out. Cracks in heat affected zone: generally, grinding method is used to eliminate cracks, and magnetic particle or dye flaw detection is used to confirm that there is no crack, and then repair welding or grinding smooth transition.The API Std 650 ground supported liquid storage tanks stiffener ring and backing strip (if used) are primary components, and they shall comply with the requirements of API 620 storage steel tank Q.2.1. The stiffener rings may be fabricated from plate using an intermittent weld on alternating sides between the web and the flange.
Except for aluminum or stainless steel tanks, all fillet welds shall consist of a minimum of two passes. The ends of the fillet welds shall be 2 in. from the rat hole (see Figure Q-1), and these welds shall be deposited by starting 2 in. from the rat hole and welding away from the rat hole. An acceptable alternative to the detail that includes stopping fillet welds 2 in. short of the rat hole would be to weld continuously through the rat hole from one side of the stiffener to the opposite side. All craters in fillet welds shall be repaired by back welding.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 Std 650 ground supported 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.The 2019 Year of the Pig is the 70th anniversary of the founding of the People's Republic of China. Growing up with the motherland, our company sang songs to the mark the 70th victory anniversary. In September, we organized all employees to sing "My Country and I" and made a film.The company will rely on its good reputation, excellent hot-rolled plates, steel pipes, steel structure products, and intimate API Std 650 ground supported liquid storage tanks after-sales service to customers. I would like to express my heartfelt thanks to the old and new friends and customers who have always given care, support and help to the company! The company sincerely hopes to establish a long-term cooperative relationship with them, mutual benefit and common development. Welcome to come and visit our API Std 650 ground supported liquid storage tanks steel mill.