API Std 650 flexible liquid storage tanks guide pole erection tolerance requirements

All API Std 650 flexible liquid storage tanks fillet welds shall consist of a minimum of two passes. The ends of the fillet welds shall be 2 in. from the rat hole, 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 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.

For floating roof API 650 tanks, the net working capacity is the liquid volume contained between the API Std 650 flexible liquid storage tanks maximum operating level (300 mm below rim for metallic type seals and 600 mm below rim for fabric type seals) and the minimum operating level (API 650 tanks roof supports clearing the tank bottom by 25 mm while set at the operating position).

According to the standard of head of API Std 650 flexible liquid storage tanks, there should be no crack, delamination, inclusion and other defects on the groove surface, which is consistent with the steel plate standard. The API Std 650 flexible liquid storage tanks head polishing can adopt different technology according to different requirements, including rough polishing, medium polishing and fine polishing. Only the materials used for the third type of pressure vessels must be retested, and the materials used for the first and second class pressure vessels are not generally re inspected.