Verification of in-Service LP Tank Pressure Ratings

The scope of the paper is to help identify the unknown pressure and vacuum ratings of low pressure storage tanks in facilities while ensuring API 2000 venting requirements are met.  A back calculation method was used to estimate tank ratings (pressure and vacuum) with retirement thicknesses for a low pressure tank found using ETank 2000 software and original tank drawings.  This method would require the venting requirement to be known based on equations in API 2000.  With the requirements of low pressure tank vents being fulfilled at an estimated rating, facility’s maintenance and inspection personnel can track the corrosion of the tank walls until estimated retirement thicknesses are reached. If this study is implemented, findings would result in improved lifetime of tanks, verification of pressure/vacuum ratings, and venting compliance with API 2000 for the lifetime of the low pressure tanks. The findings in this paper will be based on API 650 Standard, as this code will govern the sizing for most tanks found in the oil and gas industry.