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In-Service AST Inspection Report Formal External Inspection of 8,550 Gallon Tank(AST-4) Valley Pacific Petroleum Services,Inc. Page 4 1.9.2. The tank was equipped with two 2-inch diameter normal vents which terminated approximately 15 feet above ground level and were observed to be in working condition. The tank was equipped with emergency relief venting (long bolt manways) installed as required by the National Fire Protection Association (NFPA)uniform fire codes and NFPA 30 flammable and combustible liquid codes. 1.9.3. Pneumatic tank liquid level gauges for both compartments were installed and visible along the northwestern containment wall. Condor inspectors manually measured the tank volumes to compare against installed tank level gauge readings. The northern compartment manual measurement was 56.5-inches; 0.5-inch higher than the gauge reading of 56-inches. The product level in the southern compartment measured 70.5-inches; 2-inches higher than the gauge reading of 68.5-inches. Overfill alarms or vent whistles were not installed. 1.10. Grounding equipment was not installed on AST-4. 1.11. The tank was not equipped with stairways,handrails, or platforms. 1.12. Surface coatings observed on all surfaces of the tank shell, heads, and supports appeared to be in good condition. 2. Original Shell Thickness of the AST 2.1. Original tank documentation was not provided for review. 2.2. The tank manufacturer was determined by examining the nameplate installed on the tank. 2.3. The tank's nameplate identifies it with an Underwriters' Laboratories (UL) designation. This indicates the tank is manufactured to the UL 142 specification for aboveground storage of flammable liquids. 2.4. According to several ultrasonic thickness(UT)measurements,the original shell thickness is presumed to be approximately 0.250 inches or 1/4-inch rolled steel with an average thickness of 0.252 inches of remaining steel. The original thickness of the tank's heads is presumed to be approximately 0.250 inches or 1/4-inch rolled steel with an average of 0.246 inches of remaining steel. 3. Horizontal ASTs 3.1. Shell plates, welds, and ancillary equipment were inspected for indications of exterior corrosion, buckling, distortion due to stress, cracking, pinholes, and mechanical damage. There were no signs of corrosion or damage on the exterior tank surface. Minor leakage from ancillary piping at both pumps mounted on the tanks topside. 3.1.1. UT measurements and visual inspection of the tank shell revealed no significant internal or exterior corrosion. Refer to the thickness measurements and photographs attached to this report. 3.2. The tank shell was inspected for indications of modifications that may have been made in the past.Brackets and platforms for ancillary tank equipment and piping appear consistent with the original design. No evidence of modification to the original tank was identified. 3.3 INSPECTION SUMMARY The following sections provide a summary of the inspection completed for the tank. UT Measurements Summary To obtain the residual metal thickness readings, a NDT Systems TG110 —DL ultrasonic digital thickness meter equipped with a TG-560P transducer was used.The meter has a resolution of±0.001 in(±0.025 mm) intended for use on steel plate and piping materials used in storage tank applications. The meter is capable of collecting readings using a scan mode or single point mode. The meter is factory calibrated(November 23,2016)and proper operation confirmed prior to and during testing using a steel calibration block adhered t, �(� CONDOR