API 653 EXAM 2 QUESTIONS WITH 100% CORRECT ANSWERS 2024

API 653 EXAM 2 QUESTIONS WITH 100% CORRECT ANSWERS 2024 API publications necessarily address problems of what type? - ANSWERS Problems of a general nature. (Special notes section) API Standard 653 covers in service steel tanks built to what standards? - ANSWERS This standard covers steel storage tanks built to API 650 and its predecessor API 12C. (1.1.1) What API Standard always governs for tanks that have been placed in service? - ANSWERS In the case of apparent conflicts between the requirements of this standard and API 650 or its predecessor API 12C, API 653 shall govern for tanks that have been placed in service. (1.1.2) API Standard 653 employs the design principles of what standard? - ANSWERS This standard employs the principles of API 650. (1.1.3) When design and construction details are not given and are not available in the standard to which the in service tank was originally constructed, then details that will provide a level of integrity equal to the level provided by the current edition of which standard must be used? - ANSWERS The current edition of API 650 must be used. (1.1.5) Who has the ultimate responsability for complying with the provisions of API653? - ANSWERS The owner/operator. (1.2) The inspector agency of the jurisdiction in which the above ground is storage tank is operated is called what? - ANSWERS Authorized inspection agency (3.3) An employee of an authorized inspection agency certified as an AST inspector per API 653 Appendix D, is known as what? - ANSWERS Authorized inspector (3.4) What is the total metal loss divided by the period of time over which the metal loss occurred? - ANSWERS Corrosion rate (3.9) What is the definition of a "repair" to a tank? - ANSWERS Work necessary to maintain or restore a tank to a condition suitable for safe operation. (3.24) What must be done when the results of a tank inspection show that a change has occurred from the original physical condition of that tank? - ANSWERS An evaluation shall be made to determine its suitability for continued use. (4.1.1) What must be done when the cone roof tank roof plates corrode to an average thickness of less than 0.09" in any 100 in^2 area? - ANSWERS Shall be repaired or replaced. (4.2.1.2) What section of API 653 must be considered when changing the service of a tank to operation at temperatures above 200F? - ANSWERS All requirements of API 650, Appendix M. (4.2.4.3) What form of corrosion does not normally represent a significant threat to the overall structural integrity of the tank shell unless it is present in a severe and numerous form? - ANSWERS Pitting (4.3.1.3) When can widley scattered pits inside the tank shell be ignored? - ANSWERS Provided that: a) no pit depth results in the remaining shell thickness being less than one-half the minimum acceptable tank shell thickness exclusive of the corrosion allowance; and b) the sum of their dimensions along any vertical line does not exceed 2 in. in an 8-in. length (see Figure 4.2). (4.3.2.2). A tank of a single butt-weld with a back-up bar construction, built to an unknownstandard in 1940 is inspected. Corrosion is general and an evaluation of the tank's minimum thickness is required. What joint factor would you use? - ANSWERS E = 0.85. (Table 4.2) What can foundation settlement cause to appear in the shell of an AST? - ANSWERS Shell distortions. (4.3.5.2, 4.3.5.3) Unless a stress analysis is performed what is the minimum bottom plate thickness in the critical zone of the tank bottom? - ANSWERS the smaller of one-half the original bottom plate thickness or 50 % of tmin of the lower shell course, but not less than 0.1 in. (4.4.5.4) An AST operating at 250F is evaluated for continuing service. The inspector checks the tank records and finds that the tank was originally built of ASTM A516 gr60. What allowable stress should the inspector use in evaluation the minimum thicknesses of the tank's shell? - ANSWERS 32,000 * 0.80 = 25,600 (4.3.10.1.1a or Table 4.1) A six year old storage tank is inspected. The tank has a diameter of 125 feet and its maximum liquid level height is 40 feet. The tank was constructed of ASTM A283 gr C steel. The product stored in the tank has a specific gravity of 0.85. What is the Tmin for the lower shell course plate? - ANSWERS Tmin = (2.6*H*D*G)/(S*E) = (2.6*40*125*0.85)/(23600*1) = (11050)/(23600) = 0.468" (4.3.3.1) An AST that has a diameter of 121ft and a height of 40ft (five 8ft courses).Its bottom shell course has a thickness of 0.55" and a corrosion allowance of 0.1". The tank is built from ASTM A283 gr C CS. It has a joint eff of 0.85. The tank is to be hydrostatically tested. Determine the hydrostatic test height. Round to nearest 100th of a ft. - ANSWERS Ht = ((St*E*Tmin)/(2.6D)) + 1 = ((26,000*0.85*0.55)/(2.6*121)) +1 = (12155/314.6)+1 = 39.64ft (4.3.3.2) What is the risk of brittle facture failure in continued service after a tank has demosntrated the ability to whitstand the combined effects of maximum liquid level (highest stress) and lowest operating temperature without failing... great, minimal or average? - ANSWERS Minimal (5.2.2) Using Fig 5-2 of API 653, determine the lowest temperature that a tank constructed from CS of unknown thoughness may be used if its maximum shell thickness is 0.75" - ANSWERS 55F (Table 5-2) The external condtion of storage tanks shall be monitored by close visual inspection from the ground on a routine basis. The inspection can be done by owner/operator personnel, and can be done by other Auth