Tank inspectors, check

Tank fabricators and tank inspectors check new and repaired welds on floors of low-pressure tanks using soap suds. They commonly use a vacuum box to check tank floor seams. The inspection team coats a short section of weld seam with soapy water. An inspector places a custom-built rectangular box that has a clear window on the top of the soapy weld seam. A specially designed air eductor, which uses compressed air, evacuates the box. If soap bubbles appear in the box, the inspector marks the defective weld for repairs. 

Low-pressure tanks. The shell of the tank should be checked for leaks, buckles and bulges and other conditions listed above in item 7. Thickness measurements must be taken at points where corrosion is evident. Special attention should be given to the shell near the bottom on low pressure tanks. Inspectors sometimes find advanced corrosion in that area caused by corrosive soils or trapped water. Tank roofs also require detailed inspections. For safety s sake the inspector must exercise extra care to first establish that the roof will support his weight. 

These documents also provide guidance on internal and external mechanical inspections to be undertaken by a trained and competent tank inspector. All inspections and routine checks should be documented. Evaluation should include fixed roof venting, floating roof drainage and general... 

Figure 10-13 Inspectors using a vacuum box and soapy water to check for leaks in welds on the floor of low-pressure tanks.

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