API 653
API publications necessarily address problems of what type? - correct answer-Problems of a
general nature. (Special notes section)
API Standard 653 covers in service steel tanks built to what standards? - correct
answer-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? - correct
answer-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? - correct answer-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? -
correct answer-The current edition of API 650 must be used. (1.1.5)
Who has the ultimate responsability for complying with the provisions of API653? - correct
answer-The owner/operator. (1.2)
The inspector agency of the jurisdiction in which the above ground is storage tank is
operated is called what? - correct answer-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? - correct answer-Authorized inspector (3.4)
What is the total metal loss divided by the period of time over which the metal loss occurred?
- correct answer-Corrosion rate (3.9)
What is the definition of a "repair" to a tank? - correct answer-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? - correct answer-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? - correct answer-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? - correct answer-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? -
correct answer-Pitting (4.3.1.3)
When can widley scattered pits inside the tank shell be ignored? - correct answer-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? - correct answer-E = 0.85. (Table 4.2)
What can foundation settlement cause to appear in the shell of an AST? - correct
answer-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? - correct answer-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? -
correct answer-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? - correct answer-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. - correct answer-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)
API publications necessarily address problems of what type? - correct answer-Problems of a
general nature. (Special notes section)
API Standard 653 covers in service steel tanks built to what standards? - correct
answer-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? - correct
answer-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? - correct answer-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? -
correct answer-The current edition of API 650 must be used. (1.1.5)
Who has the ultimate responsability for complying with the provisions of API653? - correct
answer-The owner/operator. (1.2)
The inspector agency of the jurisdiction in which the above ground is storage tank is
operated is called what? - correct answer-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? - correct answer-Authorized inspector (3.4)
What is the total metal loss divided by the period of time over which the metal loss occurred?
- correct answer-Corrosion rate (3.9)
What is the definition of a "repair" to a tank? - correct answer-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? - correct answer-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? - correct answer-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? - correct answer-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? -
correct answer-Pitting (4.3.1.3)
When can widley scattered pits inside the tank shell be ignored? - correct answer-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? - correct answer-E = 0.85. (Table 4.2)
What can foundation settlement cause to appear in the shell of an AST? - correct
answer-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? - correct answer-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? -
correct answer-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? - correct answer-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. - correct answer-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)
