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Underwriters Laboratory UL-142 design thickness for Horizontal tanks less than 12-feet diameter <br /> is 0.24-inches. Shell thicknesses are presented in Figures 1. UT data is presented in the Appendix. <br /> Corrosion rates for tanks with thicknesses greater than 75 percent design thickness remaining are <br /> estimated at 0.01 inch per year. Once below 75 percent, a second round of testing is required in <br /> two years to accurately estimate the corrosion rate. Tank must be taken out of service and <br /> repaired or replaced once a reading of less than 50 percent is discovered. <br /> Tanks are in passing condition and within design thickness range. Minimum thickness for tank <br /> 1 was 0.225-inches, and minimum thickness or tank 2 was 0.210-inches. <br /> 3.5 Shell <br /> Tank 1's shell was in good condition. <br /> Tank 2's shell showed signs of heavy pitting. This is typical of a tank that has either been buried <br /> or sitting in soil for some time. Tank 2 also showed gouging typical of backhoe scraping during <br /> removal or transporting. The deepest pit was 1/4-th inch. It is "Recommended" this tank be <br /> replaced after the next inspection cycle of five years,as this pitting is difficult to repair and is near <br /> 50 percent through the shell thickness. <br /> 3.6 Venting: <br /> All tanks are required to have normal vents. Normal vents are required to be sized equal to or <br /> greater than final discharge piping. The oil and diesel tanks have normal vents properly sized <br /> and in good condition. Tank 1 has a normal vent of 3 inches and a fill/discharge port of 4 inches. <br /> The piping is double walled,and the inner pipe 2-inches which is less than the discharge. <br /> Tank 1 does not have an emergency vent but was designed with a manway lid which could be <br /> used as an emergency vent. It is `Required" to have a full 8-inch emergency vent installed on the <br /> manway lid or spring bolts on the lid. Tank 2 was designed without an emergency vent or a <br /> manway lid. This is typical of a UST. It is "iZequired" to have a full 8-inch emergency vent to be <br /> installed. <br /> 3.7 Liquid Level Indicators/Overfill Alarms: <br /> Liquid level monitors(LLM)are required for all tanks. Tanks 1 and 2 do not have LLM or overfill <br /> alarms. Both LLM and overfill alarms are "Required" for these tanks. <br /> 3.8 Piping <br /> Piping is designed for some flex. Piping is in adequate condition. <br /> 3.9 Bonding and Grounding. <br /> Flammable liquid tank should have proper grounding and should be equipped for bonding <br /> during filling. Electrical pumps and equipment attached to the tank increase the potential for <br /> short circuiting. Tanks do not have grounding. It is"Required" that tanks be grounded. <br /> 3 <br /> BAY AREA TANK&COATINGS, LLC 2115 E. 27TH ST VANCOUVER,WA 98661 <br /> OFFICE 360.314.2448 FAX 360.314.2691 <br />