Procedures for calibrating upright cylindrical tanks used primarily for the storage of petroleum liquids. Chapter 2.2A addresses necessary measurement procedures to determine total and incremental tank volumes and procedures for computing volumes. Both metric and customary units are included. The metric units reflect what is available in commercial equipment. The standard also provides guidelines for recalibration and computerization of capacity tables. Chapter 2.2A should be used in conjunction with Chapter 2.2B. These two standards combined supersede the previous API Standard 2550, Measurement and Calibration of Upright Cylindrical Tank.