This document provides useful information and recommended practices for the maintenance and inspection of atmospheric and low-pressure storage tanks. While these maintenance and inspection guidelines may apply to other types of tanks@ these practices are intended primarily for existing tanks which were constructed to one of the following four standards: API 12A@ API 12C@ API 620@ or API 650. This document addresses the following: a) descriptions and illustrations of the various types of storage tanks; b) new tank construction standards; c) maintenance practices; d) reasons for inspection; e) causes of deterioration; f) frequency of inspection; g) methods of inspection; h) inspection of repairs; i) preparation of records and reports; j) safe and efficient operation; k) leak prevention methods. This Recommended Practice (RP) is intended to supplement API 653@ which provides minimum requirements for maintaining the integrity of storage tanks after they have been placed in service.