API 653 CLOSED BOOK
EXAM WITH CORRECT
ANSWERS 2025
Two methods of quantifying the remaining thickness of tank bottoms are
mentioned in API 653. One method uses the formula involving "MRT". What
is the name of the other method?
a. Deterministic and Analytic
b. Methodological and Non-destructive
c. Quantitative and Destructive
d. Probabilistic and Deterministic - correct answers - Probabilistic and
Deterministic
What is the maximum out-of-plumbness allowed from the top of the shell to
the bottom of the shell on a 48' high tank?
e. 5.76"
f. 5.00"
g. 5.48"
h. 4.80" - correct answers - 5.00"
Due to strength requirements, the minimum thickness of an annular plate
ring is usually greater than:
i. 0.187"
j. 0.125"
k. 0.100"
l. 0.250" - correct answers - 0.100"
The joint between the new material of an insert plate and the old material of
the existing tank shell plate shall be:
m.Lap welded
n. Plug welded
o. Butt welded
p. Fillet welded - correct answers - Butt welded
A pressure test at least 1.5 times the shall be performed on a nozzle
installed by hot tapping after the valve has been installed on it and prior to
mounting the hot tap machine.
q. Design head
r. Operating head
s. Working head
t. Hydrostatic head - correct answers - Hydrostatic head
Cone roof storage tanks may be as large as feet in diameter.
u. 100'
v. 50'
,c. 300'
d. 80' - correct answers - 300'
The simplest type of floating roof is the:
a. Pan
b. Pontoon
c. Double deck
d. Cone - correct answers - Pan
An oxygen deficient atmosphere exists when a tank atmosphere has less
than what percent oxygen by volume?
e. 18.5%
c. 15.0%
b. 19.0%
d. 19.5% - correct answers - 19.5%
Lead-in-Air analyzers must be designed to measure Lead-in-
Air concentrations.
f. Organic
g. Inorganic
h. Radioactive
i. Liquid - correct answers - Organic
Entry into a confined space is considered to have occurred as
soon as:
j. Half the entrant's body is inside the confined space.
k. The entrants head enters the confined space.
l. A part of the entrant's body breaks the plane of an opening
into the space.
m.The entrant's head and shoulders enters the confined space. - correct
answers - A part of the entrant's body breaks the plane of an opening into
the space.
When repairs involve most of the tank bottom, it may be desirable to
displace the flammable liquids beneath the tank by:
n. Purging with CO2
o. Purging with N2
p. Water flooding
q. Using an odorized gas - correct answers - Water flooding
Tank surfaces that have been in contact with leaded gasoline should be
scraped down to bare metal. On each side of a line that might be heated
excessively by welding or other operations, an area of at least should be
scraped down to bare metal.
r. 6"
s. 24"
t. 10"
u. 12" - correct answers - 12"
What is the axis of a weld?
, a. A line drawn parallel with the base of the material.
b. A line through the center of the weld, parallel with the sides of the weld.
c. A line through the center of the weld, perpendicular with the weld.
d.A line drawn from the base to the throat of a weld - correct answers
- A line through the center of the weld, parallel with the sides of the weld
In monitoring the density limitations of radiographs, either a or step
wedge comparison film shall be used for judging film density.
e. Proportionometer
f. Galvanometer
g. Densitometer
h. Penetrameter - correct answers - Densitometer
During tank roof evaluations, roof plates corroded to an average thickness
of less than
in any 100 square inch area shall be repaired or replaced.
i. 0.06"
j. 0.12"
k. 0.10"
l. 0.09" - correct answers - 0.09"
API 653 covers minimum requirements for maintaining the integrity of
above ground storage tanks.
m.After placed in service.
n. Before
o. During construction.
p. During testing. - correct answers - After placed in service
In the evaluation of fixed roofs for continued service, particular attention
must be given to:
q. The number of columns used for a roof.
r. The size of columns vs. the roof load.
s. The possibility of internal corrosion of pipe columns.
t.The configuration of the columns and attachments. - correct
answers - The possibility of internal corrosion of pipe columns
In determining the lowest average thickness t avg (or t1) over a length of "L"
of a tank shell plate, the inspector shall use at least equally spaced
measurements over the length of "L".
u. Three
v. Six
w.Ten
x. Five - correct answers - Five
To determine if a tank is suitable for continued operation, t1 shall be greater
than or equal to t min subject to verification of all intended loadings and the
value of t2 shall be greater than or equal to what percent of t min?
EXAM WITH CORRECT
ANSWERS 2025
Two methods of quantifying the remaining thickness of tank bottoms are
mentioned in API 653. One method uses the formula involving "MRT". What
is the name of the other method?
a. Deterministic and Analytic
b. Methodological and Non-destructive
c. Quantitative and Destructive
d. Probabilistic and Deterministic - correct answers - Probabilistic and
Deterministic
What is the maximum out-of-plumbness allowed from the top of the shell to
the bottom of the shell on a 48' high tank?
e. 5.76"
f. 5.00"
g. 5.48"
h. 4.80" - correct answers - 5.00"
Due to strength requirements, the minimum thickness of an annular plate
ring is usually greater than:
i. 0.187"
j. 0.125"
k. 0.100"
l. 0.250" - correct answers - 0.100"
The joint between the new material of an insert plate and the old material of
the existing tank shell plate shall be:
m.Lap welded
n. Plug welded
o. Butt welded
p. Fillet welded - correct answers - Butt welded
A pressure test at least 1.5 times the shall be performed on a nozzle
installed by hot tapping after the valve has been installed on it and prior to
mounting the hot tap machine.
q. Design head
r. Operating head
s. Working head
t. Hydrostatic head - correct answers - Hydrostatic head
Cone roof storage tanks may be as large as feet in diameter.
u. 100'
v. 50'
,c. 300'
d. 80' - correct answers - 300'
The simplest type of floating roof is the:
a. Pan
b. Pontoon
c. Double deck
d. Cone - correct answers - Pan
An oxygen deficient atmosphere exists when a tank atmosphere has less
than what percent oxygen by volume?
e. 18.5%
c. 15.0%
b. 19.0%
d. 19.5% - correct answers - 19.5%
Lead-in-Air analyzers must be designed to measure Lead-in-
Air concentrations.
f. Organic
g. Inorganic
h. Radioactive
i. Liquid - correct answers - Organic
Entry into a confined space is considered to have occurred as
soon as:
j. Half the entrant's body is inside the confined space.
k. The entrants head enters the confined space.
l. A part of the entrant's body breaks the plane of an opening
into the space.
m.The entrant's head and shoulders enters the confined space. - correct
answers - A part of the entrant's body breaks the plane of an opening into
the space.
When repairs involve most of the tank bottom, it may be desirable to
displace the flammable liquids beneath the tank by:
n. Purging with CO2
o. Purging with N2
p. Water flooding
q. Using an odorized gas - correct answers - Water flooding
Tank surfaces that have been in contact with leaded gasoline should be
scraped down to bare metal. On each side of a line that might be heated
excessively by welding or other operations, an area of at least should be
scraped down to bare metal.
r. 6"
s. 24"
t. 10"
u. 12" - correct answers - 12"
What is the axis of a weld?
, a. A line drawn parallel with the base of the material.
b. A line through the center of the weld, parallel with the sides of the weld.
c. A line through the center of the weld, perpendicular with the weld.
d.A line drawn from the base to the throat of a weld - correct answers
- A line through the center of the weld, parallel with the sides of the weld
In monitoring the density limitations of radiographs, either a or step
wedge comparison film shall be used for judging film density.
e. Proportionometer
f. Galvanometer
g. Densitometer
h. Penetrameter - correct answers - Densitometer
During tank roof evaluations, roof plates corroded to an average thickness
of less than
in any 100 square inch area shall be repaired or replaced.
i. 0.06"
j. 0.12"
k. 0.10"
l. 0.09" - correct answers - 0.09"
API 653 covers minimum requirements for maintaining the integrity of
above ground storage tanks.
m.After placed in service.
n. Before
o. During construction.
p. During testing. - correct answers - After placed in service
In the evaluation of fixed roofs for continued service, particular attention
must be given to:
q. The number of columns used for a roof.
r. The size of columns vs. the roof load.
s. The possibility of internal corrosion of pipe columns.
t.The configuration of the columns and attachments. - correct
answers - The possibility of internal corrosion of pipe columns
In determining the lowest average thickness t avg (or t1) over a length of "L"
of a tank shell plate, the inspector shall use at least equally spaced
measurements over the length of "L".
u. Three
v. Six
w.Ten
x. Five - correct answers - Five
To determine if a tank is suitable for continued operation, t1 shall be greater
than or equal to t min subject to verification of all intended loadings and the
value of t2 shall be greater than or equal to what percent of t min?
