American Petroleum Institute Standard 653
Section 4.4.1.2 - 1998 Supplement

All tanks shall have a formal internal inspection conducted at the intervals defined by 4.4.2 or 4.4.3 below. The Authorized Inspector who is responsible for evaluation of a tank must conduct a visual inspection and assure the quality and completeness of the NDE results.  If the internal inspection is required solely for the purpose of determining the condition and integrity of the tank bottom, the internal inspection may be accomplished with the tank in-service utilizing various ultrasonic robotic thickness measurement and other on-stream inspection methods capable of assessing the thickness of the tank bottom, in combination with methods capable of assessing tank bottom integrity as described in 2.4.1. Electromagnetic methods may be used to supplement the on-stream ultrasonic inspection.  If an in-service inspection is selected, the data and information collected shall be sufficient to evaluate the thickness, corrosion rate, and integrity of the tank bottom and establish the internal inspection interval, based on tank bottom thickness, corrosion rate, and integrity, utilizing the methods included in this standard.  An individual, knowledgeable and experienced in relevant inspection methodologies, and the Authorized Inspector must review and approve the technology and techniques being used for the internal tank bottom inspection and integrity assessment.  The Authorized Inspector who is responsible for evaluation of a tank must assure the quality and completeness of the in-service NDE results.

© Solex Robotics Systems, Inc. 2000, All Rights Reserved